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Cai X, Zhou H, Lou Y, Lu B, Zhang D, Wang J, Xing D. Microbiome and antibiotic resistome in bioelectrochemical toilets for onsite treatment of fecal sludge. WATER RESEARCH 2024; 260:121956. [PMID: 38906081 DOI: 10.1016/j.watres.2024.121956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 06/14/2024] [Accepted: 06/16/2024] [Indexed: 06/23/2024]
Abstract
Effective management of fecal sludge (FS) is essential for preventing environmental and public health risks. Developing safe and efficient FS treatment technology is crucial for reducing the health risks of onsite sanitation systems. In this study, bioelectrochemical toilets (BETs) were developed to treat FS onsite. Compared with the open-circuit BETs (OC-BETs), BETs exhibited higher removal efficiencies for total organic carbon, total nitrogen, and total phosphorus. Specifically, the enhancements in removal efficiencies were 18.82 ± 1.73 %, 7.28 ± 0.32 %, and 11.41 ± 0.05 % for urine, and 19.28 ± 4.08 %, 21.65 ± 1.23 %, and 24.68 ± 0.95 % for feces, respectively. Microbiome analysis indicated that the dominant populations were affiliated with electroactive bacteria (Desulfuromonas and Pseudomonas) in the electrode biofilm of BETs. The species co-occurrence network showed that the electrode biofilm microbiome in BETs had more complex correlations than that in OC-BETs, suggesting that a weak electrical current enhanced the microbiome stability. The relative abundance of antibiotic resistance genes in BETs and OC-BETs reduced by 59.85 ± 1.32 % and 53.01 ± 2.81 % compared with the initial FS, respectively. These findings indicate that BETs are an alternative system for enhancing onsite treatment of fecal sludge and provide a theoretical foundation for the implementation of BETs.
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Affiliation(s)
- Xiaoyu Cai
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Huihui Zhou
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yu Lou
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Baiyun Lu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Dawei Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Jing Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Defeng Xing
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
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2
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Choudhury AR, Singh N, Lalwani J, Rao MG, Konyala BP, Nadella C, Nayakwadi A, Palani SG. A comparative assessment of biomethane potential of fresh fecal matter and fecal sludge and its correlation with malodor. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024:10.1007/s11356-024-33289-8. [PMID: 38625464 DOI: 10.1007/s11356-024-33289-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 04/08/2024] [Indexed: 04/17/2024]
Abstract
Comprehensive and proper management of fecal sludge (FS) is an ongoing concern in many nations. Decentralized fecal sludge treatment plants (FSTPs) are effective in this regard; however, many have experienced strong public opposition based partly on suspicion of malodor. Fecal sludge and freshly generated fecal matter (FM) samples from various FSTPs were collected, characterized, and investigated for biomethane potential. The homogenized samples were anaerobically digested for 28 days. Digestion successfully reduced total suspended solids, biochemical oxygen demand, and threshold odor number values of 97,350-97,420 mg/l, 43,230-43,260 mg/l, and 130-150 for FM, to 49,500-49,650 mg/l, 23,760-23,850 mg/l, and 3338, respectively, for FS samples. The comprehensive gas yield from Bhongir, Boduppal, and Shadnagar FS samples was 40, 55, and 31 ml, respectively. In contrast, cumulative gas generation from the FM was 26,361 ml. Digestion of FS samples also reduced concentrations of volatile solids and coliforms by 66-72% and 99%, respectively. Characterization of gas samples revealed methane and carbon dioxide concentrations as 56% and 22% for FM, and 0.4% and 61% for FS samples, respectively. Hydrogen sulfide and ammonia gas were absent in FS samples, dispelling common societal misconceptions of FSTPs being associated with malodor.
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Affiliation(s)
- Atun Roy Choudhury
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Shamshabad, 500078, Telangana, India
| | - Neha Singh
- Chadwick's FSM Laboratory, Banka BioLoo Limited, Shed No- 37, Industrial Development Area, Mallapur, 500076, Secunderabad, India
| | - Jitesh Lalwani
- Department of Civil Engineering, Vardhaman College of Engineering, Kacharam, Shamshabad, 501218, Hyderabad, India
| | - Mallikarjuna Goriparthi Rao
- Department of Civil Engineering, Chaitanya Bharathi Institute of Technology, Gandipet, 500075, Hyderabad, India
| | - Bhanu Prakash Konyala
- Department of Civil Engineering, Vardhaman College of Engineering, Kacharam, Shamshabad, 501218, Hyderabad, India
| | - Chiradeep Nadella
- Department of Civil Engineering, Vardhaman College of Engineering, Kacharam, Shamshabad, 501218, Hyderabad, India
| | - Abhishek Nayakwadi
- Department of Civil Engineering, Vardhaman College of Engineering, Kacharam, Shamshabad, 501218, Hyderabad, India
| | - Sankar Ganesh Palani
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Shamshabad, 500078, Telangana, India.
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3
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Strande L, Evans B, von Sperling M, Bartram J, Harada H, Nakagiri A, Nguyen VA. Urban Sanitation: New Terminology for Globally Relevant Solutions? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15771-15779. [PMID: 37819045 PMCID: PMC10603773 DOI: 10.1021/acs.est.3c04431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Indexed: 10/13/2023]
Abstract
Progress toward Sustainable Development Goals for global access to safe sanitation is lagging significantly. In this Feature, we propose that misleading terminology leads to errors of categorization and hinders progress toward sanitation service provision in urban areas. Binary classifications such as "offsite/onsite" and "sewered/nonsewered" do not capture the need for "transport to treatment" or the complexity of urban sanitation and should be discarded. "Fecal sludge management" is used only in the development context of low- or middle-income countries, implying separate solutions for "poor" or "southern" contexts, which is unhelpful. Terminology alone does not solve problems, but rather than using outdated or "special" terminology, we argue that a robust terminology that is globally relevant across low-, middle-, and upper-income contexts is required to overcome increasingly unhelpful assumptions and stereotypes. The use of accurate, technically robust vocabulary and definitions can improve decisions about management and selection of treatment, promote a circular economy, provide a basis for evidence-based science and technology research, and lead to critical shifts and transformations to set policy goals around truly safely managed sanitation. In this Feature, the three current modes of sanitation are defined, examples of misconceptions based on existing terminology are presented, and a new terminology for collection and conveyance is proposed: (I) fully road transported, (II) source-separated mixed transport, (III) mixed transport, and (IV) fully pipe transported.
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Affiliation(s)
- Linda Strande
- Eawag:
Swiss Federal Institute of Aquatic Science and Technology, Department of Sanitation, Water and Solid Waste for
Development (Sandec), Überlandstrasse 133, Dübendorf 8600, Switzerland
| | - Barbara Evans
- School
of Civil Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Marcos von Sperling
- Department
of Sanitary and Environmental Engineering, Federal University of Minas Gerais, Av. Antônio Carlos 6627 - Campus Pampulha, Belo Horizonte 31270-901, Brazil
| | - Jamie Bartram
- School
of Civil Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Hidenori Harada
- Graduate
School of Asian and African Area Studies, Kyoto University, Yoshida-shimoadachi-cho 46, Sakyo, Kyoto 606-8501, Japan
| | - Anne Nakagiri
- Department
of Civil and Environmental Engineering, Kyambogo University, Kyambogo Road, Kampala, P.O. Box 1, Kyambogo, Uganda
| | - Viet-Anh Nguyen
- Institute
of Environmental Science and Engineering (IESE), Hanoi University of Civil Engineering (HUCE), 55 Giai Phong Road, Hanoi 113068, Vietnam
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4
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Maqbool N, Shahid MA, Khan SJ. Situational assessment for fecal sludge management in major cities of Pakistan. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:98869-98880. [PMID: 35943647 PMCID: PMC9360668 DOI: 10.1007/s11356-022-22331-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/28/2022] [Indexed: 05/17/2023]
Abstract
With enhanced focus on global sanitation, access to toilets at the household level is increasing in developing countries although the provision of sewer networks is not expanding at the same pace. This is resulting in the adaptation of on-site sanitation facilities to contain the fecal sludge. The fecal sludge generated by the on-site sanitation facilities requires emptying, treatment, and safe end-use or disposal. In this study, the sanitation situation and need for fecal sludge management was evaluated in major cities of Pakistan including Karachi (provincial capital), Lahore (provincial capital), and Islamabad (national capital). Primary and secondary data were collected from key informant interviews of the stakeholders, national and international reports, research, and review articles. Infographics on wastewater and fecal sludge from origin to disposal were developed using a shit flow diagram tool and enabling environment was evaluated with a modified service delivery assessment tool. The results indicate that sewerage network coverage exists for 60%, 63%, and 50% of the areas in Karachi, Lahore, and Islamabad respectively. The sewerage network in major cities is old, leaking, and insufficient, thus a limited amount of wastewater reaches the treatment plants. Total wastewater treatment in Karachi and Islamabad is 10% and 9% respectively whereas, in Lahore, there is no infrastructure for the same. The safe sanitation in Lahore (8%) and Islamabad (25%) is coming from on-site sanitation systems with fecal sludge buried safely onsite. National level sanitation programs exist in the country but are limited to reducing open defecation and containments of fecal sludge only. The inclusion of complete fecal sludge management related framework, guidelines, and policies can help achieve the goal of safe sanitation for all.
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Affiliation(s)
- Nida Maqbool
- Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Sector H 12, Islamabad, Pakistan
| | - Muhammad Arslan Shahid
- Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Sector H 12, Islamabad, Pakistan
| | - Sher Jamal Khan
- Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Sector H 12, Islamabad, Pakistan.
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5
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Koulouri ME, Templeton MR, Fowler GD. Source separation of human excreta: Effect on resource recovery via pyrolysis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 338:117782. [PMID: 37015142 DOI: 10.1016/j.jenvman.2023.117782] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/13/2023] [Accepted: 03/19/2023] [Indexed: 06/19/2023]
Abstract
More people globally are now using on-site sanitation technologies than sewered connections. The management of faecal sludge generated by on-site facilities is still challenging and requires an understanding of all sanitation service chain components and their interactions; from source conditions to treatment and resource recovery. This study aimed to improve the current lack of knowledge regarding these interactions, by establishing a quantifiable relationship between human excreta source separation and resource recovery via pyrolysis. The effects of source separation of faeces and urine on biochar quality were investigated for different pyrolysis temperatures (450 °C, 550 °C, 650 °C) and this information was used to assess energy and nutrient recovery. Results quantify the benefits of urine diversion for nitrogen recovery (70% of total N losses during thermal treatment avoided) and show an increase in the liming potential of the produced faecal-based biochars. The quality of produced solid fuels is also improved when source-separated faeces (SSF) are used as a feedstock for pyrolysis, including a 50% increase in char calorific value. On the other hand, biochars from mixed urine and faeces (MUF) are more rich in phosphorus and potassium, and surface morphology investigation indicates higher porosity compared to SSF biochars. The high salinity of MUF biochars should be considered before agricultural applications. For both biochar types (SSF, MUF), the presence of phosphate compounds of high fertiliser value was confirmed by X-ray diffraction analysis, and temperatures around 500 °C are recommended to optimise nutrient and carbon behaviour when pyrolysing human excreta. These findings can be used for the design of circular faecal sludge management systems, linking resource recovery objectives to source conditions, and vice-versa. Ultimately, achieving consistent resource recovery from human excreta can act as an incentive for universal access to safe and sustainable sanitation.
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Affiliation(s)
- Maria E Koulouri
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
| | - Michael R Templeton
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
| | - Geoffrey D Fowler
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
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6
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Jakariya M, Nahla T, Ahmed S, Ishtiak T, Islam MT, Alam MS, Ali A, Uddin Ruman MS, Saad S, Bhattacharya P, Van der Voorn T, Islam MA, Hossain MS, Amin KA, Saha SK, Rahman I, Adib HI, Mahzabin L, Murshed MF, Ahmed R, Jahan H, Ferdausi M, Barceló D, Sonne C. ICT-based solution for efficient fecal sludge management: An experience from Bangladesh. Heliyon 2023; 9:e15200. [PMID: 37123923 PMCID: PMC10133653 DOI: 10.1016/j.heliyon.2023.e15200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 03/27/2023] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
In Bangladesh, people primarily depend on on-site sanitation facilities (OSSF) with an immense challenge in achieving safe sanitation due to unplanned infrastructure development, improper management of fecal sludge, and inadequate monitoring. The commitment of attaining Sustainable Development Goals (SDG) 6.2 (ensuring safe sanitation for all) by 2030 requires immediate attention in the management of fecal sludge for low-middle income countries. This paper presented the findings, challenges, and possible ways forward from a study conducted to provide data for Information and Communication Technology (ICT)-based fecal sludge management (FSM) at a municipality in the northwest of Bangladesh. A total of 18,808 households and 407 institutions in Saidpur municipality, a non-sewered town in Nilphamari district, were studied to understand the type of containment structures and on-ground desludging practices. The study showed around 10% of containments were connected to the drains illegally, 95% of the people in Saidpur practiced unsafe disposal, and 7% still practiced open defecation. To identify these malpractices, the study also implemented an ICT-based sustainable solution through a web application that enabled the local administrator to have a global look at the sanitation scenario of the municipality. The dashboard was developed to create a total sanitation monitoring system, identify defaulters, allow target-based safe managed sanitation service strategies, and ensure sustainability in FSM. The study highlighted the accessibility of vacuum truck services projecting through a spatial map and identified methods to empty the septic tanks where Vacutag services are unavailable by engaging local pit emptiers. The innovative approach of fecal sludge management will help not only to improve the existing sanitation practices but also raise community awareness to ensure sustainable sanitation system. Altogether, the web system will work as a medium to manage the faecal sludge for the existing co-compost plant where the faeces is converted into organic soil conditioner, creating prospects for a green business mechanism.
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Affiliation(s)
- Md. Jakariya
- Department of Environmental Science and Management, North South University, Bangladesh
- Corresponding author.
| | - Turasa Nahla
- Department of Environmental Science and Management, North South University, Bangladesh
| | - Silvia Ahmed
- Department of Electrical and Computer Engineering, North South University, Bangladesh
| | - Taoseef Ishtiak
- Department of Electrical and Computer Engineering, North South University, Bangladesh
| | | | - Md. Sajadul Alam
- Department of Environmental Science and Management, North South University, Bangladesh
| | - Ahmed Ali
- Department of Environmental Science and Management, North South University, Bangladesh
| | | | - Saman Saad
- Department of Environmental Science and Management, North South University, Bangladesh
| | - Prosun Bhattacharya
- Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, SE-10044, Stockholm, Sweden
| | - Tom Van der Voorn
- University of Osnabrück, Institute of Environmental Systems Research, 49069, Osnabrück, Germany
| | - Md. Aminul Islam
- Advanced Molecular Lab, Department of Microbiology, President Abdul Hamid Medical College, Karimganj, Kishoreganj, Bangladesh
| | | | | | | | | | | | - Lamia Mahzabin
- Department of Environmental Science and Management, North South University, Bangladesh
| | - Mohammed Fahim Murshed
- Institute of Disaster Management and Vulnerability Studies, University of Dhaka, Bangladesh
| | - Ragib Ahmed
- Department of Environmental Science and Management, North South University, Bangladesh
| | - Hasin Jahan
- WaterAid Bangladesh, Dhaka, 1213, Bangladesh
| | - Marufa Ferdausi
- Department of Electrical and Computer Engineering, North South University, Bangladesh
| | - Damià Barceló
- Water, Environmental and Food Chemistry Unit (ENFOCHEM), Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish National Research Council (CSIC), C. Jordi Giron 18-26, 08034, Barcelona, Spain
| | - Christian Sonne
- Aarhus University Department of Environmental Science, Roskilde, Denmark
- Corresponding author.
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7
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Shaw K, Vogel M, Andriessen N, Hardeman T, Dorea CC, Strande L. Towards globally relevant, small-footprint dewatering solutions: Optimal conditioner dose for highly variable blackwater from non-sewered sanitation. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 321:115961. [PMID: 35998530 DOI: 10.1016/j.jenvman.2022.115961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 08/03/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Globally, the sanitation needs of three billion people are met by non-sewered sanitation. Small-footprint treatment technologies are needed that are appropriate for dense urban areas. Blackwater (BW) (or fecal sludge), contains more than 95% liquid, and dewatering it without conditioning requires large footprints. Chemically-enhanced dewatering with conditioners is a promising option to increase dewatering performance and reduce required footprints. However, before implementation of this solution there is a need for increased knowledge on selection and dosing of conditioners. This study evaluated bio-based and synthetic conditioners (chitosan, tannin-, and starch-based, synthetic with and without poly-acrylamide) with 14 types of BW from five countries. The supernatant after settling with jar-tests was analyzed to quantify optimal dose and dewatering performance. The reduction of total chemical oxygen demand (COD) was >55%, achieved by removal of particulate constituents with mainly soluble COD remaining in the supernatant. A reduction in particulate COD could lead to increased efficiency of soluble COD in supernatant treatment. Bio-based conditioners are as effective as synthetic conditioners, and when performance was variable, it was due to differing properties of TSS, TS, EC and pH. Optimal conditioner dose for synthetic conditioners and chitosan could be predicted using concentrations of total solids (TS) (R2 > 0.7), whereas optimal dose for starch- and tannin-based conditioners could be predicted with electrical conductivity (EC) (R2 > 0.8), and colloid titration (R2 > 0.8). In addition, real-time optical TSS and EC sensors could accurately predict chitosan dose for fresh BW treated at source (R2 = 0.97, R2 = 0.95). This study validates that use of conditioners for dewatering with highly variable BW can be implemented with real-time measurements for optimal dose, in globally relevant implementations.
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Affiliation(s)
- Kelsey Shaw
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Department of Sanitation, Water and Solid Waste for Development (Sandec), Überlandstrasse 133, 8600, Dübendorf, Switzerland; Department of Civil Engineering, University of Victoria, British Columbia, Canada.
| | - Michael Vogel
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Department of Sanitation, Water and Solid Waste for Development (Sandec), Überlandstrasse 133, 8600, Dübendorf, Switzerland.
| | - Nienke Andriessen
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Department of Sanitation, Water and Solid Waste for Development (Sandec), Überlandstrasse 133, 8600, Dübendorf, Switzerland.
| | - Thomas Hardeman
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Department of Sanitation, Water and Solid Waste for Development (Sandec), Überlandstrasse 133, 8600, Dübendorf, Switzerland.
| | - Caetano C Dorea
- Department of Civil Engineering, University of Victoria, British Columbia, Canada.
| | - Linda Strande
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Department of Sanitation, Water and Solid Waste for Development (Sandec), Überlandstrasse 133, 8600, Dübendorf, Switzerland.
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8
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Rowles LS, Morgan VL, Li Y, Zhang X, Watabe S, Stephen T, Lohman HAC, DeSouza D, Hallowell J, Cusick RD, Guest JS. Financial Viability and Environmental Sustainability of Fecal Sludge Treatment with Pyrolysis Omni Processors. ACS ENVIRONMENTAL AU 2022; 2:455-466. [PMID: 36164351 PMCID: PMC9502014 DOI: 10.1021/acsenvironau.2c00022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 11/30/2022]
Abstract
![]()
Omni Processors (OPs) are community-scale systems for
non-sewered
fecal sludge treatment. These systems have demonstrated their capacity
to treat excreta from tens of thousands of people using thermal treatment
processes (e.g., pyrolysis), but their relative sustainability is
unclear. In this study, QSDsan (an open-source Python package) was
used to characterize the financial viability and environmental implications
of fecal sludge treatment via pyrolysis-based OP technology treating
mixed and source-separated human excreta and to elucidate the key
drivers of system sustainability. Overall, the daily per capita cost
for the treatment of mixed excreta (pit latrines) via the OP was estimated
to be 0.05 [0.03–0.08] USD·cap–1·d–1, while the treatment of source-separated excreta
(from urine-diverting dry toilets) was estimated to have a per capita
cost of 0.09 [0.08–0.14] USD·cap–1·d–1. Operation and maintenance of the OP is a critical
driver of total per capita cost, whereas the contribution from capital
cost of the OP is much lower because it is distributed over a relatively
large number of users (i.e., 12,000 people) for the system lifetime
(i.e., 20 yr). The total emissions from the source-separated scenario
were estimated to be 11 [8.3–23] kg CO2 eq·cap–1·yr–1, compared to 49 [28–77]
kg CO2 eq·cap–1·yr–1 for mixed excreta. Both scenarios fall below the estimates of greenhouse
gas (GHG) emissions for anaerobic treatment of fecal sludge collected
from pit latrines. Source-separation also creates opportunities for
resource recovery to offset costs through nutrient recovery and carbon
sequestration with biochar production. For example, when carbon is
valued at 150 USD·Mg–1 of CO2, the
per capita cost of sanitation can be further reduced by 44 and 40%
for the source-separated and mixed excreta scenarios, respectively.
Overall, our results demonstrate that pyrolysis-based OP technology
can provide low-cost, low-GHG fecal sludge treatment while reducing
global sanitation gaps.
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Affiliation(s)
- Lewis Stetson Rowles
- Institute for Sustainability, Energy, and Environment, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Victoria L. Morgan
- Institute for Sustainability, Energy, and Environment, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Yalin Li
- Institute for Sustainability, Energy, and Environment, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Xinyi Zhang
- Department of Civil & Environmental Engineering, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Shion Watabe
- Department of Civil & Environmental Engineering, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Tyler Stephen
- Department of Civil & Environmental Engineering, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Hannah A. C. Lohman
- Department of Civil & Environmental Engineering, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Derek DeSouza
- Biomass Controls PBC, Woodstock, Connecticut 06281, United States
| | - Jeff Hallowell
- Biomass Controls PBC, Woodstock, Connecticut 06281, United States
| | - Roland D. Cusick
- Department of Civil & Environmental Engineering, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Jeremy S. Guest
- Institute for Sustainability, Energy, and Environment, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
- Department of Civil & Environmental Engineering, University of Illinois Urbana−Champaign, Urbana, Illinois 61801, United States
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9
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Sam SB, Ward BJ, Niederdorfer R, Morgenroth E, Strande L. Elucidating the role of extracellular polymeric substances (EPS) in dewaterability of fecal sludge from onsite sanitation systems, and changes during anaerobic storage. WATER RESEARCH 2022; 222:118915. [PMID: 35921716 DOI: 10.1016/j.watres.2022.118915] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
As the importance of fecal sludge management (FSM) is increasingly being realized, the need for adequately designed and functioning fecal sludge (FS) treatment plants is also increasing. Research to fill this gap is only emerging and dewatering is a key challenge for developing sustainable treatment solutions. This study evaluated the effect of extracellular polymeric substances (EPS) on dewaterability of FS, and how EPS and dewaterability change during anaerobic storage (as a proxy for time in onsite containment). EPS was extracted from FS and activated sludge using Na2CO3 and sonication and added to sludge samples to determine the effect on dewaterability. The results confirmed that an increase in EPS had a direct impact of decreasing FS dewaterability (as capillary suction time). In this context, we evaluated FS degradation during anaerobic storage, the effect of anaerobic storage time on EPS, EPS fractions and particle size distribution, and the effect of variations in these factors on FS dewaterability. Variations in EPS, EPS fraction and particle size distribution during anaerobic storage were less than expected and average VS reduction of 20% was recorded over 7 weeks. Although anaerobic digestion was verified (biogas production), the results indicate that kinetics of degradation of FS is different from wastewater sludges. Comparatively, EPS fractions in FS were 70 - 75% lower and with higher fractions of humic-like substances than wastewater sludges. Although EPS significantly affects FS dewaterability, anaerobic storage time is not a predictor of dewaterability.
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Affiliation(s)
- Stanley B Sam
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zurich, Institute of Environmental Engineering, 8093 Zurich, Switzerland.
| | - Barbara J Ward
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zurich, Institute of Environmental Engineering, 8093 Zurich, Switzerland
| | - Robert Niederdorfer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Eberhard Morgenroth
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zurich, Institute of Environmental Engineering, 8093 Zurich, Switzerland
| | - Linda Strande
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
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10
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Kocbek E, Garcia HA, Hooijmans CM, Mijatović I, Al-Addous M, Dalala Z, Brdjanovic D. Novel semi-decentralised mobile system for the sanitization and dehydration of septic sludge: a pilot-scale evaluation in the Jordan Valley. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:42016-42036. [PMID: 34718952 PMCID: PMC9148295 DOI: 10.1007/s11356-021-17018-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 10/09/2021] [Indexed: 06/13/2023]
Abstract
The provision of effective sanitation strategies has a significant impact on public health. However, the treatment of septic sludge still presents some challenges worldwide. Consequently, innovative technologies capable of an effective and efficient sludge treatment, mostly at a decentralized level, are in high demand to improve sanitation provision. To address this problem, this study evaluates a novel semi-decentralised mobile faecal sludge treatment system, the pilot-system for which consists of a combination of several individual processes including mechanical dewatering (MD), microwave (MW) drying, and membrane filtration (ultrafiltration [UF] and reverse osmosis [RO]). The system evaluation was carried out by treating raw, partially digested faecal sludge (FS) from septic tanks-hence, septic sludge (SS)-in the Jordan Valley, Jordan. The pilot-scale system exhibited an effective and flexible treatment performance for (i) sanitizing faecal sludge and related liquid streams (MW and UF); (ii) reducing the treated sludge mass (and sludge volume) (MD and MW); and (iii) producing a high-quality treated liquid stream ideal for water reclamation applications (UF and RO). The MD process removed approximately 99% of the initial SS water content. The MW drying system completely removed E. coli and dehydrated the dewatered sludge at low energy expenditures of 0.75 MJ kg-1 and 5.5 MJ kg-1, respectively. Such energy expenditures can be further reduced by approximately 40% by recovering energy in the condensate and burning the dried sludge, which can then be reused inland applications. The membrane filtration system (UF and RO) was able to produce high-quality treated water that is ideal for the water reuse applications that irrigation requires, as well as meeting the Jordanian standard 893/2006. In addition, the system can also be powered by renewable energy sources, such as photovoltaic energy. Therefore, this research demonstrates that the evaluated semi-decentralised mobile system is technically feasible for the in situ treatment of SS (sanitization and dehydration), while also being effective for simultaneously recovering valuable resources, such as energy, water, and nutrients.
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Affiliation(s)
- Eva Kocbek
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
- Department of Environmental Engineering and Water Technology, IHE-Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, The Netherlands.
- Tehnobiro d.o.o., Heroja Nandeta 37, 2000, Maribor, Slovenia.
| | - Hector A Garcia
- Department of Environmental Engineering and Water Technology, IHE-Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, The Netherlands
| | - Christine M Hooijmans
- Department of Environmental Engineering and Water Technology, IHE-Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, The Netherlands
| | - Ivan Mijatović
- Tehnobiro d.o.o., Heroja Nandeta 37, 2000, Maribor, Slovenia
| | - Mohammad Al-Addous
- Department of Energy Engineering, German Jordanian University, P.O.Box 35247, Amman, 11180, Jordan
| | - Zakariya Dalala
- Department of Energy Engineering, German Jordanian University, P.O.Box 35247, Amman, 11180, Jordan
| | - Damir Brdjanovic
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
- Department of Environmental Engineering and Water Technology, IHE-Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, The Netherlands
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11
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Manga M, Kolsky P, Rosenboom JW, Ramalingam S, Sriramajayam L, Bartram J, Stewart J. Public health performance of sanitation technologies in Tamil Nadu, India: Initial perspectives based on E. coli release. Int J Hyg Environ Health 2022; 243:113987. [PMID: 35623255 PMCID: PMC9227721 DOI: 10.1016/j.ijheh.2022.113987] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 04/27/2022] [Accepted: 05/11/2022] [Indexed: 01/31/2023]
Abstract
Sanitation is intended to reduce the spread and burden of diseases transmitted from excreta. Pathogen reduction from excreta before sludge or effluent discharge to the environment would seem a logical and useful performance indicator for sanitation systems. However, the relative magnitudes of pathogen release from common sanitation technologies are not well understood. We, therefore, investigated the feasibility of performance measurement of different sanitation technologies in Tamil Nadu, India in reducing the release of the pathogen indicator Escherichia coli (E. coli). After conducting users’ surveys and technical assessments of the locally prevalent sanitation systems, we classified them into 7 distinct categories (based on both observed physical characteristic and usage) within a widely-accepted physical typology. Faecal sludge and wastewater samples were collected and analysed for E. coli and total solids from 136 household systems, 24 community systems, and 23 sanitary sewer oveflows. We estimated the average volumetric release rates of wastewater and faecal sludge from the different sanitation technologies. Average daily per capita E. coli release was computed, and used as one indicator of the public health performance of technologies. We found that on-site installations described by owners as “septic systems” included diverse forms of tanks and pits of uncertain performance. We observed a statistically significant difference in the average daily per capita E. coli release from different sanitation technologies (p = 0.00001). Pathogen release from the studied on-site sanitation technologies varied by as much as 5 orders of magnitude from “lined pits” (5.4 Log10 E. coli per person per day) to “overflowing sanitary sewers” and “direct discharge pipes” (10.3–10.5 Log10 E. coli per person per day). Other technologies lay between these extremes, and their performances in E. coli removal also varied significantly, in both statistical and practical terms. Our results suggest that although faecal sludge management along the sanitation service chain is important, sanitation planners of the observed systems (and probably elsewhere) should direct higher priority to proper management of the liquid effluents from these systems to minimize public health hazards. We conclude that (i) the work demonstrates a new and promising approach for estimating the public health performance of differing sanitation technologies, (ii) if E.coli is accepted as an indicator of the public health hazard of releases from sanitation systems, our results strongly suggest that safe containment of excreta for an extended period substantially reduces pathogen numbers and the risk of pathogen release into the environment; and (iii) there are some simple but little-used technical improvements to design and construction of on-site sanitation systems which could significantly reduce the release of pathogens to the environment.
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Affiliation(s)
- Musa Manga
- The Water Institute at UNC, Department of Environmental Sciences and Engineering, The Gillings School of Global Public Health, University of North Carolina at Chapel Hill, 4114 McGavran Hall, Campus Box # 7431, NC, 27599, Chapel Hill, NC, USA; Department of Construction Economics and Management, College of Engineering, Design, Art and Technology (CEDAT), Makerere University, P.O. Box 7062, Kampala, Uganda.
| | - Pete Kolsky
- The Water Institute at UNC, Department of Environmental Sciences and Engineering, The Gillings School of Global Public Health, University of North Carolina at Chapel Hill, 4114 McGavran Hall, Campus Box # 7431, NC, 27599, Chapel Hill, NC, USA
| | | | - Sudha Ramalingam
- PSG Institute of Medical Sciences and Research, Off, Avinashi Rd, Masakalipalayam, Peelamedu, Coimbatore, Tamil Nadu, 641004, India
| | - Lavanya Sriramajayam
- PSG Institute of Medical Sciences and Research, Off, Avinashi Rd, Masakalipalayam, Peelamedu, Coimbatore, Tamil Nadu, 641004, India
| | - Jamie Bartram
- The Water Institute at UNC, Department of Environmental Sciences and Engineering, The Gillings School of Global Public Health, University of North Carolina at Chapel Hill, 4114 McGavran Hall, Campus Box # 7431, NC, 27599, Chapel Hill, NC, USA; School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Jill Stewart
- The Water Institute at UNC, Department of Environmental Sciences and Engineering, The Gillings School of Global Public Health, University of North Carolina at Chapel Hill, 4114 McGavran Hall, Campus Box # 7431, NC, 27599, Chapel Hill, NC, USA
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12
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Beard VA, Satterthwaite D, Mitlin D, Du J. Out of sight, out of mind: Understanding the sanitation crisis in global South cities. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 306:114285. [PMID: 35016141 PMCID: PMC8819159 DOI: 10.1016/j.jenvman.2021.114285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/21/2021] [Accepted: 12/09/2021] [Indexed: 05/28/2023]
Abstract
Global monitoring efforts do not provide a clear picture of the challenge of managing human waste at the city scale. Where cities do not provide universal access to publicly managed sanitation systems, households and communities find their own solutions resulting in a patchwork of approaches to removing human waste from places where people live. In dense urban environments, the absence of a coordinated approach can create serious public health problems. In the absence of comparable city-level data, we analyze primary and secondary data from 15 cities and 15 informal settlements in sub-Saharan Africa, South Asia, and Latin America. Across these regions, our study finds that 62 percent of human waste is not safely managed. We also find that, while many cities have a proportion of households connected to sewers, none of the 15 cities safely manage human waste at scale. In the absence of sewers, on-site fecal sludge management systems place enormous responsibility on households and private providers, and unaffordable sanitation options result in risky sanitation practices.
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Affiliation(s)
| | | | - Diana Mitlin
- University of Manchester, International Institute for Environmental Development, UK
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13
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Mahon JM, Knappe J, Gill LW. Sludge accumulation rates in septic tanks used as part of the on-site treatment of domestic wastewater in a northern maritime temperate climate. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 304:114199. [PMID: 34864407 DOI: 10.1016/j.jenvman.2021.114199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/05/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
On-site domestic wastewater treatment systems (DWTS) are used by a significant fraction of the world's population and are used by one third of the population in Ireland. The effective operation of these DWTS requires regular desludging and so knowledge of expected filling rates is essential for both the homeowner as well as the municipalities which accept this sludge in licensed premises; yet few studies have attempted to quantify the sludge accumulation in such decentralized systems. Field studies were carried out on 27 septic tanks across Ireland to quantify sludge accumulation rates from which optimum desludging frequencies for use in Ireland have then been determined. Sludge accumulation was found to be very high in the first 12 months of system operation (approximately 250 L/person/y) but dropped off to below 150 L/person/y after 2 years. Such volumetric accumulation rates appear high compared to the few other reported international studies; however, measured solids accumulation rates, were low compared to international estimates, ranging from 1 to 10 kg/person/y. An equation for optimal desludging frequencies between 3 and 5 years has been formulated for various tank sizes and occupancy based on the Irish field data and previous international research - 5 years being the maximum allowable interval between desludging before the limiting volume of 50% sludge in the tank is reached.
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Affiliation(s)
- Joanne Mac Mahon
- Department of Civil, Structural and Environmental Engineering, Museum Building, Trinity College Dublin, College Green, Dublin 2, Ireland
| | - Jan Knappe
- Department of Civil, Structural and Environmental Engineering, Museum Building, Trinity College Dublin, College Green, Dublin 2, Ireland
| | - Laurence W Gill
- Department of Civil, Structural and Environmental Engineering, Museum Building, Trinity College Dublin, College Green, Dublin 2, Ireland.
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14
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Chandana N, Rao B. A critical review on sludge management from onsite sanitation systems: A knowledge to be revised in the current situation. ENVIRONMENTAL RESEARCH 2022; 203:111812. [PMID: 34363803 DOI: 10.1016/j.envres.2021.111812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 07/27/2021] [Accepted: 07/27/2021] [Indexed: 05/28/2023]
Abstract
Access to safe excreta disposal is a basic human right and an essential element of human development. Developing countries (like India) have constructed millions of toilets with on-site sanitation technologies (OSTs). However, these OSTs lack the required management system for collection, transportation and disposal of Faecal Sludge (FS, sludge getting accumulated in OST), leading to considerable water and soil pollution. The major challenge in FS Management is the collation of scattered data and concentrated experiences (i.e., existing knowledge remains with the practitioners in the field without a written record). Therefore, a critical review of existing knowledge on OST, FS collection, transportation, and its utilisation is essential. This study highlighted shortcomings associated with existing OST, FS collection, transportation, and treatment systems. Furthermore, this study provided a framework for appropriate selection of OST based on available sanitation chains, and a critical analysis of FS characteristics (i.e., total solids, pH, electrical conductivity, biological oxygen demand, chemical oxygen demand, and pathogens of FS ranged from 830 to 72000 mg/L, 6.8 to 7.8, 1.9 to 3.5 mS/cm, 500-5000 mg/L, 100 to 49,000 mg/L, and 106 to 107 E-coli and 103 to 104 parasitic worms per litre of FS, respectively) to design treatment systems for FS utilisation as a resource in agricultural, aqua-culture, and construction application.
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Affiliation(s)
- N Chandana
- Centre for Technology Alternatives for Rural Areas, Indian Institute of Technology Bombay, Mumbai, 400076, India.
| | - Bakul Rao
- Centre for Technology Alternatives for Rural Areas, Indian Institute of Technology Bombay, Mumbai, 400076, India.
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15
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Krueger BC, Fowler GD, Templeton MR, Septien S. Faecal sludge pyrolysis: Understanding the relationships between organic composition and thermal decomposition. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 298:113456. [PMID: 34364246 DOI: 10.1016/j.jenvman.2021.113456] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/26/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
Sludge treatment is an integral part of faecal sludge management in non-sewered sanitation settings. Development of pyrolysis as a suitable sludge treatment method requires thorough knowledge about the properties and thermal decomposition mechanisms of the feedstock. This study aimed to improve the current lack of understanding concerning relevant sludge properties and their influence on the thermal decomposition characteristics. Major organic compounds (hemicellulose, cellulose, lignin, protein, oil and grease, other carbohydrates) were quantified in 30 faecal sludge samples taken from different sanitation technologies, providing the most comprehensive organic faecal sludge data set to date. This information was used to predict the sludge properties crucial to pyrolysis (calorific value, fixed carbon, volatile matter, carbon, hydrogen). Samples were then subjected to thermogravimetric analysis to delineate the influence of organic composition on thermal decomposition. Septic tanks showed lower median fractions of lignin (9.4%dwb) but higher oil and grease (10.7%dwb), compared with ventilated improved pit latrines (17.4%dwb and 4.6%dwb respectively) and urine diverting dry toilets (17.9%dwb and 4.7%dwb respectively). High fixed carbon fractions in lignin (45.1%dwb) and protein (18.8%dwb) suggested their importance for char formation, while oil and grease fully volatilised. For the first time, this study provided mechanistic insights into faecal sludge pyrolysis as a function of temperature and feedstock composition. Classification into the following three phases was proposed: decomposition of hemicellulose, cellulose, other carbohydrates, proteins and, partially, lignin (200-380 °C), continued decomposition of lignin and thermal cracking of oil and grease (380-500 °C) and continued carbonisation (>500 °C). The findings will facilitate the development and optimisation of faecal sludge pyrolysis, emphasising the importance of considering the organic composition of the feedstock.
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Affiliation(s)
- Benedict C Krueger
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
| | - Geoffrey D Fowler
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK
| | - Michael R Templeton
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK
| | - Santiago Septien
- Water, Sanitation & Hygiene Research & Development Centre, University of KwaZulu-Natal, Durban, 4041, South Africa
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16
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Somorin T, Getahun S, Septien S, Mabbet I, Kolios A, Buckley C. Isothermal drying characteristics and kinetics of human faecal sludges. Gates Open Res 2021; 4:67. [PMID: 34056550 PMCID: PMC8135097 DOI: 10.12688/gatesopenres.13137.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2021] [Indexed: 11/20/2022] Open
Abstract
Background: Drying is an important step for the thermochemical conversion of solid fuels, but it is energy-intensive for treating highly moist materials. Methods: To inform the thermal treatment of faecal sludge (FS), this study investigated the drying characteristics and kinetics of various faecal wastes using thermogravimetric analysis and isothermal heating conditions. Results: The findings show that FS from the anaerobic baffled reactor (ABR) and ventilated improved pit latrines (VIP) exhibit similar drying characteristics, with maximum drying rates at 0.04 mg/min during a constant rate period that is followed by a distinct falling rate period. On the contrary, fresh human faeces (HF) and FS from urine diversion dry toilets (UDDT) exhibited a falling rate period regime with no prior or intermittent constant rate periods. The absence of a constant rate period in these samples suggested limited amounts of unbound water that can be removed by dewatering and vice versa for VIP and ABR faecal sludges. The activation energies and effective moisture diffusivity for the sludges varied from 28 to 36 kJ/mol and 1.7·10
-7 to 10·10
-7 m
2/s at 55°C and sludge thickness of 3mm. The Page model was consistent in modelling the different sludges across all temperatures. Conclusions: These results presented in this study can inform the design and development of innovative drying methods for FS treatment.
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Affiliation(s)
- Tosin Somorin
- Chemical and Process Engineering, University of Strathclyde, Glasgow, G1 1XQ, UK
| | - Samuel Getahun
- Pollution Research Group, University of Kwazulu-Natal, Durban, 4041, South Africa
| | - Santiago Septien
- Pollution Research Group, University of Kwazulu-Natal, Durban, 4041, South Africa
| | - Ian Mabbet
- Department of Chemistry, Swansea University, Swansea, UK
| | - Athanasios Kolios
- Naval Architecture, Ocean & Marine Engineering, University of Strathclyde, Glasgow, G1 1XQ, UK
| | - Chris Buckley
- Pollution Research Group, University of Kwazulu-Natal, Durban, 4041, South Africa
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17
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Ward BJ, Andriessen N, Tembo JM, Kabika J, Grau M, Scheidegger A, Morgenroth E, Strande L. Predictive models using "cheap and easy" field measurements: Can they fill a gap in planning, monitoring, and implementing fecal sludge management solutions? WATER RESEARCH 2021; 196:116997. [PMID: 33744658 DOI: 10.1016/j.watres.2021.116997] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/19/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
The characteristics of fecal sludge delivered to treatment plants are highly variable. Adapting treatment process operations accordingly is challenging due to a lack of analytical capacity for characterization and monitoring at many treatment plants. Cost-efficient and simple field measurements such as photographs and probe readings could be proxies for process control parameters that normally require laboratory analysis. To investigate this, we evaluated questionnaire data, expert assessments, and simple analytical measurements for fecal sludge collected from 421 onsite containments. This data served as inputs to models of varying complexity. Random forest and linear regression models were able to predict physical-chemical characteristics including total solids (TS) and ammonium (NH4+-N) concentrations, and solid-liquid separation performance including settling efficiency and filtration time (R2 from 0.51-0.66) based on image analysis of photographs (sludge color, supernatant color, and texture) and probe readings (conductivity (EC) and pH). Supernatant color was the best predictor of settling efficiency and filtration time, EC was the best predictor of NH4+-N, and texture was the best predictor of TS. Predictive models have the potential to be applied for real-time monitoring and process control if a database of measurements is developed and models are validated in other cities. Simple decision tree models based on the single classifier of containment type can also be used to make predictions about citywide planning, where a lower degree of accuracy is required.
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Affiliation(s)
- Barbara J Ward
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland.
| | - Nienke Andriessen
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - James M Tembo
- Department of Civil and Environmental Engineering, School of Engineering, University of Zambia, Lusaka, Zambia
| | - Joel Kabika
- Department of Civil and Environmental Engineering, School of Engineering, University of Zambia, Lusaka, Zambia
| | - Matt Grau
- Department of Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Andreas Scheidegger
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Eberhard Morgenroth
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
| | - Linda Strande
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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18
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Resource-Efficient Characterisation of Pit Latrine Sludge for Use in Agriculture. SUSTAINABILITY 2021. [DOI: 10.3390/su13094702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Resource recovery through reuse of by-products of the sanitation chain presents a great potential towards ensuring universal access to safely managed sanitation. Many developing countries are faced with uncertainty over public and environmental health concerns associated with use of faecal sludge in agriculture. Due to resource constraints, limited data exists on the characteristics of faecal sludge to inform proper and safe use in agriculture. Despite predictive characterisation being demonstrated to be a resource-efficient approach to generate data in other fields, its application in agricultural resource recovery from faecal sludge is lacking in the literature. This paper explored predictive modelling as a less resource-intensive approach for characterisation of nutrients and pathogens in faecal sludge. Specifically, it investigated the extent to which gravimetric parameters could predict nutrients and pathogens in pit latrine sludge from informal settlements in the cities of Malawi. The study explored predictive models to estimate total ammoniacal nitrogen (TAN), total phosphorus (TP), E.coli and helminth eggs from gravimetric parameters (total solids [TS] and total volatile solids [TVS]) in pit latrine sludge. The models developed in the study allow substantially reliable estimation of TAN (R2pred = 75.4%) and TP (R2pred = 78.2%); they also provide moderately reliable predictions for E.coli (R2pred = 69.1%) and helminth eggs (R2pred = 74.3%) from total solids. Since total solids are easy and inexpensive to measure, the models present an option that can reduce resource requirement for characterisation of pit latrine sludge for informed decision-making when using pit latrine sludge in agriculture. In the absence of data on faecal sludge characteristics at the national level, the models provide a starting point for estimation of pathogens and nutrients in sludge for agricultural use. However, stepwise refinement of the models needs to be done through their validation for different types of sludge and inclusion of spatially available demographic, technical and environmental (SPA-DET) data.
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19
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Krueger BC, Fowler GD, Templeton MR. Critical analytical parameters for faecal sludge characterisation informing the application of thermal treatment processes. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 280:111658. [PMID: 33246749 DOI: 10.1016/j.jenvman.2020.111658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/22/2020] [Accepted: 11/06/2020] [Indexed: 06/12/2023]
Abstract
Thermal processes for the treatment of faecal sludge such as pyrolysis or combustion offer complete destruction of pathogens, whilst allowing for energy and nutrient recovery. The development of such processes is currently constrained by a lack of knowledge on thermally relevant faecal sludge characteristics. This study investigated thirty faecal sludge samples from three sanitation technologies (ventilated improved pit latrines (VIP), urine diverting dry toilets (UD), septic tanks (ST)) and compared these by non-parametric statistical analysis. A focus was placed on parameters necessary for thermal process development and recoverable nutrient concentrations. The relevant characteristics ranged widely within technology groups. Calorific values and ash concentrations of 2.1-25.7 MJ/kg and 9.5-88.4% were observed for STs, of 9.2-13.9 MJ/kg and 40.9-61.5% for VIPs and of 3.9-18.1 MJ/kg and 18.8-81.3% for UDs. These two parameters show a strong linear inverse correlation and determine the minimum dewatering requirements from which a net energy recovery may be possible. Results suggest that more than 90% of samples can meet these requirements following commonly used dewatering technologies. A comparison across technologies provided strong evidence that the faecal sludge source significantly influences sludge composition, emphasized by higher median ratios of fixed carbon to volatile matter in VIPs (0.23) and UDs (0.23) compared to STs (0.15). The sanitation technology also influenced recoverable nutrient concentrations, with phosphorus and potassium concentrations generally ranging between 5.8-49.2 g/kg and 1.4-26.1 g/kg respectively. Compared to STs, median concentrations of phosphorus and potassium in VIPs were 3.4 and 3.8 times higher respectively, and 3.0 and 8.8 times higher in UDs. The findings highlight the importance of considering the faecal sludge source in the development of thermal treatment processes. This study provides critical knowledge to further develop such processes through modelling, experimental and scaled approaches.
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Affiliation(s)
- Benedict C Krueger
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK.
| | - Geoffrey D Fowler
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK
| | - Michael R Templeton
- Department of Civil and Environmental Engineering, Imperial College London, SW7 2AZ, UK
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20
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Spuhler D, Scheidegger A, Maurer M. Ex-ante quantification of nutrient, total solids, and water flows in sanitation systems. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 280:111785. [PMID: 33339625 DOI: 10.1016/j.jenvman.2020.111785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
To prioritise sustainable sanitation systems in strategic sanitation planning, indicators such as local appropriateness or resource recovery have to be known at the pre-planning phase. The quantification of resource recovery remains a challenge because existing substance flow models require large amounts of input data and can therefore only be applied for a few options at a time for which implementation examples exist. This paper aims to answer two questions: How can we predict resource recovery and losses of sanitation systems ex-ante at the pre-planning phase? And how can we do this efficiently to consider the entire sanitation system option space? The approach builds on an existing model to create all valid sanitation systems from a set of conventional and emerging technologies and to evaluate their appropriateness for a given application case. It complements the previous model with a Substance Flow Model (SFM) and with transfer coefficients from a technology library to quantify nutrients (phosphorus and nitrogen), total solids (as an indicator for energy and organics), and water flows in sanitation systems ex ante. The transfer coefficients are based on literature data and expert judgement. Uncertainties resulting from the variability of literature data or ignorance of experts are explicitly considered, allowing to assess the robustness of the model output. Any (future) technologies or additional products can easily be added to the library. The model is illustrated with a small didactic example showing how 12 valid system configurations are generated from a few technologies, and how substance flows, recovery ratios, and losses to soil, air, and water are quantified considering uncertainties. The recovery ratios vary between 0 and 28% for phosphorus, 0-10% for nitrogen, 0-26% for total solids, and 0-12% for water. The uncertainties reflect the high variability of the literature data but are comparable to those obtained in studies using a conventional post-ante material flow analysis (generally about 30% variability at the scale of a an urban area). Because the model is fully automated and based on literature data, it can be applied ex-ante to a large and diverse set of possible sanitation systems as shown with a real application case. From the 41 technologies available in the library, 101,548 systems are generated and substance flows are modelled. The resulting recovery ratios range from nothing to almost 100%. The two examples also show that recovery depend on technology interactions and has therefore to be assessed for all possible system configurations and not at the single technology level only. The examples also show that there exist trade-offs among different types of reuse (e.g. energy versus nutrients) or different sustainability indicators (e.g. local appropriateness versus resource recovery). These results show that there is a need for such an automated and generic approach that provides recovery data for all system configurations already at the pre-planning phase. The approach presented enables to integrate transparently the best available knowledge for a growing number of sanitation technologies into a planning process. The resulting resource recovery and loss ratios can be used to prioritise resource efficient systems in sanitation planning, either for the pre-selection or the detailed evaluation of options using e.g. MCDA. The results can also be used to guide future development of technology and system innovations. As resource recovery becomes more relevant and novel sanitation technologies and system options emerge, the approach presents itself as a useful tool for strategic sanitation planning in line with the Sustainable Development Goals (SDGs).
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Affiliation(s)
- Dorothee Spuhler
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; Institute of Civil, Environmental and Geomatic Engineering, ETH Zürich, 8093, Zurich, Switzerland.
| | - Andreas Scheidegger
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland
| | - Max Maurer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; Institute of Civil, Environmental and Geomatic Engineering, ETH Zürich, 8093, Zurich, Switzerland
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21
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Characterization and Prediction of Fecal Sludge Parameters and Settling Behavior in Informal Settlements in Nairobi, Kenya. SUSTAINABILITY 2020. [DOI: 10.3390/su12219040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The safe management of fecal sludge (FS) relies on different treatments, processes, and disposal options in different contexts. Waste transfer stations can improve FS management particularly in resource-constrained areas, including low-income urban informal settlements, by providing a safe discharge and treatment location. Low-footprint options for FS treatment are sensitive to the characteristics of incoming FS, which are typically highly variable, difficult to predict, and differ significantly from the characteristics of traditional wastewater. The success of low-footprint technologies relies on the monitoring of incoming FS characteristics, such as total solids (TS), total suspended solids (TSS), chemical oxygen demand (COD), ammonia, electrical conductivity (EC), and pH. Monitoring the characteristics of incoming FS typically relies on the use of a laboratory, which can be expensive and time-consuming, particularly in resource-constrained areas. Useful correlations between easy to measure parameters and difficult to measure parameters may provide useful information related to the monitoring of FS, while reducing the need for laboratory analysis. In this paper, we describe a sampling campaign at a waste transfer station in Nairobi, Kenya managed by Sanergy Inc., to characterize and observe settling behavior of FS collected from manually emptied pit latrines. The investigation found that easy to measure parameters (e.g., TS, turbidity) could be used to approximate difficult to measure parameters (COD, TSS). Additionally, rapid measurements (turbidity) could be used to approximate time-intensive parameters (TS, COD, TSS) to aid in the design, operation and monitoring of FS treatment facilities in resource and space-constrained areas.
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Spuhler D, Germann V, Kassa K, Ketema AA, Sherpa AM, Sherpa MG, Maurer M, Lüthi C, Langergraber G. Developing sanitation planning options: A tool for systematic consideration of novel technologies and systems. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 271:111004. [PMID: 32778289 DOI: 10.1016/j.jenvman.2020.111004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/18/2020] [Accepted: 06/21/2020] [Indexed: 06/11/2023]
Abstract
To provide access to sustainable sanitation for the entire world population, novel technologies and systems have been developed. These options are often independent of sewers, water, and energy and therefore promise to be more appropriate for fast-growing urban areas. They also allow for resource recovery and and are adaptable to changing environmental and demographic conditions what makes them more sustainable. More options, however, also enhance planning complexity. Structured decision making (SDM) can help balance opposing interests. Yet, most of the current research focuses on the selection of a preferred option, assuming that a set of appropriate options is available. There is a lack of reproducible methods for the identification of sanitation system planning options that can consider the growing number of available technology and the many possible system configurations. Additionally, there is a lack of data, particularly for novel options, to evaluate the various sustainability criteria for sanitation.To overcome this limitation, we present a novel software supported approach: the SANitation sysTem Alternative GeneratOr (Santiago). To be optimally effective, Santiago is required to be integrated into an SDM approach. In this paper, we present all the elements that such an integration requires and illustrate these methods at the case of Arba Minch, a fast growing town in Ethiopia. Based on this example and experiences from other cases, we discuss the lessons learnt and present the advantages potentially brought by Santiago for sanitation planning The integration requires four elements: a set of technologies to be looked at, decision objectives for sustainable sanitation, screening criteria to evalute technology appropriateness, and about the technologies and the casea. The main output is a set of sanitation system options that is locally appropriate, diverse in order to reveal trade-offs, and of a manageable size. To support the definition of decision objectives, we developed a generic objective hierarchy for sustainable sanitation. Because one of the main challenges lies in the quantification of screening criteria, we established the data for 27 criteria and 41 technologies in a library.The case studies showed, that if the integration is successful, then Santiago can provide substantial benefits: (i) it is systematic and reproducible; (ii) it opens up the decision space with novel and potentially more appropriate solutions; (iii) it makes international data accessible for more empirical decision making; (iv) it enables decisions based on strategic objectives in line with the sustainable development goals; (v) it allows to prioritise appropriate and resource efficient systems right from the beginning (vi) and it contributes to a more citywide inclusive approach by birding strategic objectives with an area-based appropriateness assessment. The here presented approach enables the prioritisation of appropriate and resource efficient sanitation technologies and systems in strategic planning. Thereby this approach contributes to SDG 6.2, 6.3, and 11, sustainable sanitation for all.
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Affiliation(s)
- Dorothee Spuhler
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland.
| | - Verena Germann
- BOKU Vienna, Institute of Sanitary Engineering and Water Pollution Control, Vienna, Austria
| | - Kinfe Kassa
- Arba Minch University, Faculty of Water Supply and Environmental Engineering, Arba Minch, Ethiopia
| | - Atekelt Abebe Ketema
- Bahir Dar University, Faculty of Civil and Water Resources Engineering, Bahir Dar, Ethiopia
| | | | | | - Max Maurer
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland
| | - Christoph Lüthi
- ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland
| | - Guenter Langergraber
- BOKU Vienna, Institute of Sanitary Engineering and Water Pollution Control, Vienna, Austria
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Lohman HAC, Trimmer JT, Katende D, Mubasira M, Nagirinya M, Nsereko F, Banadda N, Cusick RD, Guest JS. Advancing Sustainable Sanitation and Agriculture through Investments in Human-Derived Nutrient Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:9217-9227. [PMID: 32589417 DOI: 10.1021/acs.est.0c03764] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The sixth Sustainable Development Goal seeks to achieve universal sanitation, but a lack of progress due to inhibiting factors (e.g., limitations in financial resources, sociocultural conditions, household decision-making) demands innovative approaches to meet this ambitious goal. Resource recovery may generate income to offset sanitation costs while also enhancing agriculture through increased access to agricultural nutrients. The objective of this work was to determine if resource recovery sanitation can be a profitable business model in a specific context (Kampala, Uganda) and to explore the potential for this approach to translate to other Sub-Saharan African contexts. A techno-economic analysis was performed to evaluate the financial viability of two nutrient recovery systems and business models in urban communities in Kampala under two financing scenarios: (1) Startup relying on partial sanitation aid, and (2) Self-sustaining without philanthropic financing. Results show profitability can be achieved at a nutrient selling price at or below fertilizer market value in Uganda. Recoverable nutrients from the total population without at least basic sanitation services, in 10 Sub-Saharan African countries, are the same magnitude as nutrients distributed in subsidy programs (30-450% of distributed nutrients), indicating a potential to offset inorganic fertilizer consumption or increase nutrient availability. This research makes a case to support innovative sanitation strategies and the development and financial support of human-derived fertilizer markets in areas with poor fertilizer and sanitation access.
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Affiliation(s)
- Hannah A C Lohman
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - John T Trimmer
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - David Katende
- Community Integrated Development Initiatives, Zzimewe Road, Kampala, Uganda
| | - Muwonge Mubasira
- Community Integrated Development Initiatives, Zzimewe Road, Kampala, Uganda
| | - Maria Nagirinya
- Community Integrated Development Initiatives, Zzimewe Road, Kampala, Uganda
| | - Fred Nsereko
- Community Integrated Development Initiatives, Zzimewe Road, Kampala, Uganda
| | - Noble Banadda
- Department of Agricultural and Bio-Systems Engineering, Makerere University, University Road, Kampala, Uganda
| | - Roland D Cusick
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - Jeremy S Guest
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, Illinois 61801, United States
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Pirosca S, Clarke M, Treweek S. Learning from Cochrane systematic reviews: what improvements do these suggest for the design of trials? F1000Res 2020; 9:178. [PMID: 32399204 PMCID: PMC7194492 DOI: 10.12688/f1000research.22635.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/23/2020] [Indexed: 11/20/2022] Open
Abstract
Background: Many randomised trials have serious methodological flaws that fatally undermine their results, which makes the research wasteful. This is of concern for many, including those doing systematic reviews that include trials. Cochrane systematic reviews have a section called ' Implications for research', which allows authors of the review to present their conclusions on how future research might be improved. Looking at these conclusions might highlight priority areas for improvement. Methods: We focused on the Cochrane Schizophrenia Review Group and the Multiple sclerosis and rare diseases of the central nervous system Review Group (the MS Review Group). Reviews with citation dates between 2009 and 2019 were identified and the recommendations of review authors in ' Implications for research' were put into categories. Results: Between 2009 and 2019 we identified 162 reviews for the Schizophrenia Review Group and 43 reviews for the MS Review Group. We created 22 categories of recommendations in total, of which 12 were common to both groups. The five most used categories were the same for both: better choice of outcomes; better choice of intervention/comparator; longer follow-up; larger sample size; use of validated scales. Better choice of outcomes and/or intervention/comparator was recommended in over 50% of reviews. Longer follow-up and larger sample size were recommended in over a third, with use of validated scales being suggested in around a fifth of reviews. There was no obvious pattern of improvement over time for trials included in systematic reviews published by both groups. Conclusions: We suggest that trialists working in these and other areas ask themselves, or are compelled to do so by others (e.g. funders), why they have chosen their outcomes, intervention and comparator, whether follow-up is long enough, if the sample size is big enough and whether the scales they choose to measure their outcomes are appropriate.
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Affiliation(s)
- Stefania Pirosca
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Mike Clarke
- Northern Ireland Methodology Hub, Queen's University Belfast, Belfast, UK
| | - Shaun Treweek
- Health Services Research Unit, University of Aberdeen, Aberdeen, UK
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25
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Somorin T, Getahun S, Septien S, Mabbet I, Kolios A, Buckley C. Isothermal drying characteristics and kinetics of human faecal sludges. Gates Open Res 2020; 4:67. [DOI: 10.12688/gatesopenres.13137.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2020] [Indexed: 11/20/2022] Open
Abstract
Background: Drying is an important step for the thermochemical conversion of solid fuels, but it is energy-intensive for treating highly moist materials. Methods: To inform the thermal treatment of faecal sludge (FS), this study investigated the drying characteristics and kinetics of various faecal wastes using thermogravimetric analysis and isothermal heating conditions. Results: The findings show that FS from anaerobic baffled reactor (ABR) and ventilated improved pit (VIP) latrines exhibit similar drying characteristics, with maximum drying rates at 0.04 mg/min during a constant rate period that is followed by a distinct falling rate period. On the contrary, fresh human faeces (HF) and FS from urine-diverting dry toilets (UDDT) exhibited a falling rate period regime with no prior or intermittent constant rate periods. The absence of constant rate period in these samples suggested limited amounts of unbound water that can be removed by dewatering and vice versa for VIP and ABR faecal sludges. The activation energies and effective moisture diffusivity for the sludges varied from 20 to 30 kJ/mol and 3∙10-7 to 1∙10-5 m2/s at 55°C and sludge thickness of 3mm. The Page model was consistent in modelling the different sludges across all temperatures. Conclusions: These results presented in this study can inform the design and development of innovative drying methods for FS treatment.
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Freihardt J. Can Citizen Science using social media inform sanitation planning? JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 259:110053. [PMID: 31929032 DOI: 10.1016/j.jenvman.2019.110053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/22/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
Improving the sanitation situation in a community that relies on on-site sanitation requires information about the quantity and quality of faecal sludge (FS) produced. Existing tools for data collection about FS characteristics are either imprecise or very costly. As information and communication technologies are becoming more available in low-income countries, Citizen Science is becoming an option for the collection of sanitation data. This study used an online survey distributed via social media to predict FS characteristics (Total Solids (TS), Total Suspended Solids (TSS), Volatile Suspended Solids (VSS), Chemical Oxygen Demand (COD) and Sludge Volume Index (SVI)) at 40 households in Blantyre, Malawi. Furthermore, the study investigated whether and how an online survey could yield cost-effective and representative information about the sanitation situation at the household level. Facebook and WhatsApp both introduced a bias towards higher income households as low-income households still lack access to smartphones and internet. WhatsApp (€1.01/reply) was significantly cheaper than Facebook (€3.00/reply) and conventional data generation with household interviewers (€1.47-2.20/reply). Monetary incentives generated more replies than pure social messaging. TSS, VSS and COD were significantly correlated to TS. The slope of the regression line of COD to TS (0.97) was similar to one reported for Uganda (0.88), suggesting that the ratio of COD to TS might be independent of the location. Statistically significant median differences of TS concentrations were found for the survey parameters "system type" and "solid waste", making these parameters candidates for predictors of FS characteristics. The sample size was too small for the other survey parameters to detect any differences statistically. Overall, using social media in a Citizen Science approach appears to be a promising new tool for FS characterization. In the current form, it can probably not replace other data collection tools, but rather complement them as a cost-efficient method to gain an initial assessment. Besides sanitation planning, social media and the Citizen Science approach could be employed for data collection in various fields of development cooperation.
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Affiliation(s)
- Jan Freihardt
- Institute of Environmental Engineering, ETH Zurich, 8093, Zurich, Switzerland.
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Sagoe G, Danquah FS, Amofa-Sarkodie ES, Appiah-Effah E, Ekumah E, Mensah EK, Karikari KS. GIS-aided optimisation of faecal sludge management in developing countries: the case of the Greater Accra Metropolitan Area, Ghana. Heliyon 2019; 5:e02505. [PMID: 31687595 PMCID: PMC6819848 DOI: 10.1016/j.heliyon.2019.e02505] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 09/09/2019] [Accepted: 09/18/2019] [Indexed: 11/25/2022] Open
Abstract
This study employed GIS tools to help optimise faecal sludge (FS) management in the Greater Accra Metropolitan Area (GAMA) and its environs in Ghana. First, the rates of excreta generation, FS generation and FS collection were quantified based on literature, census and FS discharge data obtained from treatment plants in the study area. Next, we mapped the FS collection to the administrative areas in GAMA based on discharge records obtained from Lavender Hill, the main faecal treatment (FTP) and estimated the travel distance and travel time from the various FS desludging neighbourhoods to the plant. The results of the study show that the excreta and FS generation rates in GAMA are 604 L/cap/yr and 4,137 L/cap/yr, respectively. About 1 million m3 of FS was collected and treated in the study area in 2018, with a collection rate of 244 L/cap/yr. The private sector dominates this collection, haulage and treatment of FS in GAMA. The GIS analysis has provided fundamental data that will be useful in rationalising the FS emptying and transport cost in the study area. Moreover, it revealed that about 20–40% of the localities were outside the 15–25 km sustainable maximum transport distance recommended by some scholars. Finally, the findings highlight the importance of looking beyond administrative boundaries when planning for FS management logistics and infrastructure and also show that the most impoverished communities in the Accra metropolis may not necessarily be the least served when it comes to FS collection and haulage.
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Affiliation(s)
- Gideon Sagoe
- Sewerage Systems Ghana Ltd, P. O. Box GP 1630, Accra, Ghana
| | | | | | - Eugene Appiah-Effah
- Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Elsie Ekumah
- Sewerage Systems Ghana Ltd, P. O. Box GP 1630, Accra, Ghana
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