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Liu X, Wu F, Zhang M, Wan C. Role of potassium ferrate in anaerobic digestion of waste activated sludge: Phenotypes and genotypes. BIORESOURCE TECHNOLOGY 2023; 383:129247. [PMID: 37247789 DOI: 10.1016/j.biortech.2023.129247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 05/31/2023]
Abstract
The specific effects of potassium ferrate (PF) on acid and methane production in anaerobic digestion need further exploration. This study comprehensively investigated the role of PF in organic matter conversion in waste activated sludge (WAS) digestion. Due to the high pH produced by PF self-decomposition, the hydrolysis of organic matter was promoted, whereas the methanogenesis was inhibited. PF could further directly oxidize protein and polysaccharides released by hydrolysis to produce volatile fatty acids (VFAs) and involve in the transformation of ammonia nitrogen. PF could induce the enrichment of functional genes related to fermentation pathways and lessen those related to methanogenesis, and the phylum resistant to PF oxidation and the strains capable of producing VFAs were enriched, resulting in VFAs accumulation. This study analyzed the participation way of PF in anaerobic digestion and provided a theoretical basis for the application of PF in promoting VFAs recovery from sludge digestion.
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Affiliation(s)
- Xiang Liu
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Fengjie Wu
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Min Zhang
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Chunli Wan
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China.
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Hu J, Li Z, Wu Z, Tao W. Potassium ferrate coupled with freezing method enhances methane production from sludge anaerobic digestion. BIORESOURCE TECHNOLOGY 2021; 332:125112. [PMID: 33857862 DOI: 10.1016/j.biortech.2021.125112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/25/2021] [Accepted: 03/27/2021] [Indexed: 06/12/2023]
Abstract
This study proposed a novel sludge pretreatment technology by combining freezing with potassium ferrate (PF) for synergistically enhancing the methane yield from sludge anaerobic digestion. Experimental results showed that the methane production was promoted from 170.1 ± 5.6 to 223.8 ± 7.0 mL/g VSS (volatile suspended solids) when pretreated by freezing coupled with 0.05 g/g TSS (total suspended solids) PF, with 31.6% increase. Kinetic model analysis indicated that the methane production potential and hydrolysis rate of sludge after combined pretreatment were enhanced by 32.0% and 15.0%, respectively. Mechanism studies revealed that freezing coupled with PF pretreatment effectively disrupted both extracellular polymeric substances (EPS) and microbial cells in sludge, consequently resulted in violent sludge disintegration. All the microbes responsible for hydrolysis, acidification and methanogenesis were found to be enriched by co-treatment of freezing and PF. Moreover, the fecal coliform in pretreated sludge was largely inactivated after anaerobic digestion.
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Affiliation(s)
- Jiawei Hu
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
| | - Zhuo Li
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
| | - Zhigen Wu
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Wenquan Tao
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
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Golub N, Shynkarchuk A, Kozlovets O, Xinhua S. Influence of Heavy Metals on the Process of Anaerobic Fermentation of Biomass by the Consortia of Anaerobic Microorganisms. INNOVATIVE BIOSYSTEMS AND BIOENGINEERING 2020. [DOI: 10.20535/ibb.2020.4.4.211227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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The disintegration of excess sludge enhanced by short-term interaction with potassium ferrate: Characteristics and mechanism. J Taiwan Inst Chem Eng 2020. [DOI: 10.1016/j.jtice.2020.12.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Hu J, Guo B, Li Z, Eshtiaghi N, Tao W. Revealing the mechanisms for potassium ferrate affecting methane production from anaerobic digestion of waste activated sludge. BIORESOURCE TECHNOLOGY 2020; 317:124022. [PMID: 32829117 DOI: 10.1016/j.biortech.2020.124022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
This study investigated the issue of potassium ferrate (PF) affecting anaerobic methane generation from sludge by a set of experimental and model analyses. Experimental results indicated that the methane production was significantly promoted from 164.7 to 204.1 mL/g VSS (volatile suspended solids) with PF dosage enhanced from 0 to 0.05 g/g TSS (total suspended solids). Further enhancement of PF dosage reduced methane production, which even decreased to 135.4 mL/g VSS when PF dosage increased to 0.1 g/g TSS. Model-based analysis showed that except for methane production potential, the methane production rate was also promoted by PF treatment, which was sufficiently enhanced from 8.80 to 11.88 mL/g VSS/d when PF dosage was 0.05 g/g TSS. Mechanism studies indicated that PF not only promoted sludge disintegration, but also enhanced the proportion of biodegradable organics in sludge liquor, and the digestion potential of the non-biodegradable humus and lignocellulose were promoted.
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Affiliation(s)
- Jiawei Hu
- State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; UN Environment-Tongji Institute of Environment for Sustainable Development, Siping Road, Shanghai 200092, China
| | - Bing Guo
- State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Zhuo Li
- State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
| | - Nicky Eshtiaghi
- Chemical and Environmental Engineering, School of Engineering, RMIT University, Victoria 3001, Australia
| | - Wenquan Tao
- State Key Laboratory of Pollution Control and Resource Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
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Hu J, Li Z, Zhang A, Mao S, Jenkinson IR, Tao W. Using a strong chemical oxidant, potassium ferrate (K 2FeO 4), in waste activated sludge treatment: A review. ENVIRONMENTAL RESEARCH 2020; 188:109764. [PMID: 32531522 DOI: 10.1016/j.envres.2020.109764] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
The ever-increasing production of waste activated sludge (WAS) has become a widespread problem to sewage treatment plants around the world. Among the multitudinous sludge treatment methods, chemical oxidation is considered as an excellent technology with both high efficiency and low investment cost. As an eco-friendly oxidant, potassium ferrate (PF) has attracted great attention in sludge treatment over the past decade. The applications of PF have demonstrated advantages in: (1) sludge dewatering; (2) minimization; (3) anaerobic fermentation; (4) removal of pollutants. This review summarizes recent work on the effects of PF on these four aspects of facilitating sludge disposal. Meanwhile, the underlying mechanisms for the diverse applications of PF on sludge treatment are analyzed. Furthermore, the shortages and knowledge gaps on current PF oxidizing methods are discussed, and directions for further research to simultaneously enhance treatment efficiency and reduce processing cost are suggested as well.
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Affiliation(s)
- Jiawei Hu
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, PR China; UN Environment-Tongji Institute of Environment for Sustainable Development, Siping Road, Shanghai, 200092, PR China
| | - Zhuo Li
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, PR China.
| | - Ai Zhang
- College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai, 201620, China
| | - Shun Mao
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, PR China
| | - Ian R Jenkinson
- Agency for Consultation and Research in Oceanography, 19320, La Roche Canillac, France
| | - Wenquan Tao
- State Key Laboratory of Pollution Control and Resource Reuse, International Joint Research Center for Sustainable Urban Water System, College of Environmental Science & Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, PR China
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Osman MEH, Abo-Shady AM, Elshobary ME, Abd El-Ghafar MO, Abomohra AEF. Screening of seaweeds for sustainable biofuel recovery through sequential biodiesel and bioethanol production. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:32481-32493. [PMID: 32506400 DOI: 10.1007/s11356-020-09534-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 05/29/2020] [Indexed: 02/05/2023]
Abstract
The present study evaluated the sequential biodiesel-bioethanol production from seaweeds. A total of 22 macroalgal species were collected at different seasons and screened based on lipid and carbohydrate contents as well as biomass production. The promising species was selected, based on the relative increase in energy compounds (REEC, %), for further energy conversion. Seasonal and annual biomass yields of the studied species showed significant variations. The rhodophyte Amphiroa compressa and the chlorophyte Ulva intestinalis showed the highest annual biomass yield of 75.2 and 61.5 g m-2 year-1, respectively. However, the highest annual carbohydrate productivity (ACP) and annual lipid productivity (ALP) were recorded for Ulva fasciata and Ulva intestinalis (17.0 and 3.0 g m-2 year-1, respectively). The later was selected for further studies because it showed 14.8% higher REEC value than Ulva fasciata. Saturated fatty acids (SAFs) showed 73.4%, with palmitic acid as a dominant fatty acid (43.8%). Therefore, biodiesel showed high saturation degree, with average degree of unsaturation (ADU) of 0.508. All the measured biodiesel characteristics complied the international standards. The first route of biodiesel production (R1) from Ulva intestinalis showed biodiesel recovery of 32.3 mg g-1 dw. The hydrolysate obtained after saccharification of the whole biomass (R2) and lipid-free biomass (R3) contained 1.22 and 1.15 g L-1, respectively, reducing sugars. However, bioethanol yield from R3 was 0.081 g g-1 dw, which represented 14.1% higher than that of R2. Therefore, application of sequential biofuel production using R3 resulted in gross energy output of 3.44 GJ ton-1 dw, which was 170.9% and 82.0% higher than R1 and R2, respectively. The present study recommended the naturally-grown Ulva intestinalis as a potential feedstock for enhanced energy recovery through sequential biodiesel-bioethanol production.
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Affiliation(s)
- Mohamed E H Osman
- Botany and Microbiology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt
| | - Atef M Abo-Shady
- Botany and Microbiology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt
| | - Mostafa E Elshobary
- Botany and Microbiology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt
- School of Food & Biological Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Mahasen O Abd El-Ghafar
- Botany and Microbiology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt
| | - Abd El-Fatah Abomohra
- Botany and Microbiology Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt.
- Department of Environmental Engineering, School of Architecture and Civil Engineering, Chengdu University, Chengdu, 610106, China.
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Kouzi AI, Puranen M, Kontro MH. Evaluation of the factors limiting biogas production in full-scale processes and increasing the biogas production efficiency. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:28155-28168. [PMID: 32415437 PMCID: PMC7334254 DOI: 10.1007/s11356-020-09035-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Biogas production from sewage sludge volatile solids (VS) by anaerobic digestion slows down towards the end of the process, among inhibitory factors being pH increase upon ammonia accumulation, poorly digestible biomaterials, and high fixed solid (FS) content. The possibility of concentrating the digested sludge VS (41.7-56.6% on a dry weight basis) by surface and bottom layer separation with biogas post-production was studied. Furthermore, the potential to recycle concentrated VS and digested sludge back to the process after adjusting pH 7.0 to optimal for biogas-producing microbes and after acid, alkali, thermal, and sonolytic treatments was examined. In general, pH 7.0 control alone improved biogas production from the recycled digested sludge the most. An equally good improvement in biogas production was achieved by recycling the digested sludge, which had been heated until ammonia had evaporated and the pH dropped to 7.0 (1-2 h, 75 °C), and at the same time, VS was degraded. The biogas production from the sonicated and recycled sludge was almost as good as from the pH-adjusted, or heat-treated recycled sludge. After the acid and base treatments of the digested sludge, the recycled sludge yielded often the lowest biogas volume, as the added chemicals increased the FS concentration, which proved to be a more important inhibitory factor than poorly degradable VS. The high FS content significantly reduced the benefits of the treatments. By separating the surface and bottom layers with biogas post-production, the surface layer of VS was concentrated to 51.6-61.8%, while different compositions of the layers affected the biogas production.
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Affiliation(s)
- Afamia I Kouzi
- Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme, University of Helsinki, Niemenkatu 73, 15140, Lahti, Finland
| | | | - Merja H Kontro
- Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme, University of Helsinki, Niemenkatu 73, 15140, Lahti, Finland.
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Sawalha H, Maghalseh M, Qutaina J, Junaidi K, Rene ER. Removal of hydrogen sulfide from biogas using activated carbon synthesized from different locally available biomass wastes - a case study from Palestine. Bioengineered 2020; 11:607-618. [PMID: 32463312 PMCID: PMC8291793 DOI: 10.1080/21655979.2020.1768736] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The main aim of this study was to remove hydrogen sulfide (H2S) from biogas by adsorption using synthesized activated carbon prepared using locally available biomass. The effect of the type of precursors, impregnation reagent and bed height was studied in continuous reactors. Three types of biomass wastes (almond shells, eucalyptus and coffee grains) were collected, grinded, sieved, pyrolyzed at 500°C and impregnated with chemical reagents such as potassium hydroxide or zinc chloride. Adsorption tests were performed using a fixed bed filter filled with the produced activated carbon. The highest biochar yield of 36% was obtained eucalyptus followed by almond shells (28.5%) and coffee grains (24%), respectively. The highest adsorption capacity and removal efficiency were obtained with eucalyptus followed by almond shells and coffee grains, respectively. For instance, eucalyptus showed an adsorption capacity of ~690 (mg hydrogen sulfide/g adsorbent) followed by almond (230 mg hydrogen sulfide/g adsorbent) and coffee grains (22 mg hydrogen sulfide/g adsorbent). As an impregnation reagent, potassium hydroxide gave the highest adsorption efficiency and capacity than zinc chloride. Furthermore, the breakthrough time with KOH (180 min) was higher than ZnCl2 (70 min). Increasing the bed height during continuous breakthrough tests increased the adsorption capacity and hydrogen sulfide removal efficiency. The results of this study showed that the adsorption efficiency of the synthesized activated carbon and consequently the hydrogen sulfide removal efficiency could be fine-tuned by selecting an appropriate biomass precursor and proper impregnation reagent.
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Affiliation(s)
- Hassan Sawalha
- Renewable Energy and Environment Research Unit, Mechanical Engineering Department, Palestine Polytechnic University , Hebron, Palestine
| | - Maher Maghalseh
- Renewable Energy and Environment Research Unit, Electrical Engineering Department, Palestine Polytechnic University , Hebron, Palestine
| | - Janna Qutaina
- Renewable Energy and Environment Research Unit, Mechanical Engineering Department, Palestine Polytechnic University , Hebron, Palestine
| | - Kholoud Junaidi
- Renewable Energy and Environment Research Unit, Mechanical Engineering Department, Palestine Polytechnic University , Hebron, Palestine
| | - Eldon R Rene
- Department of Environmental Engineering and Water Technology, IHE Delft Institute for Water Education , Delft, The Netherlands
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Zhong D, Li J, Ma W, Qian F. Clarifying the synergetic effect of magnetite nanoparticles in the methane production process. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:17054-17062. [PMID: 32146670 DOI: 10.1007/s11356-020-07828-y] [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: 08/17/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
Magnetite nanoparticles (Fe3O4 NPs) were applied in an anaerobic semi-continuous tank reactor (ASTR) to investigate its effect on the anaerobic digestion (AD) of acetate synthetic wastewater. The Fe3O4 NPs corrosion could create a more favorable micro-environment to enhance the methanogens activity. The chemical oxygen demand (COD) removal efficiency and methane production in test (ASTRT) were 31.1% and 101.5% higher than those in control (ASTRC). With the addition of Fe3O4 NPs, the concentration of key coenzyme (F420 and M) increased from averagely 0.523 and 5.352 μmol/g-VSS to 0.956 and 9.267 μmol/g-VSS, and the content of soluble microbial products (SMPs) significantly increased. Additionally, the high-throughput 16S rRNA gene sequencing further confirmed that the percentage of hydrogen-utilizing methanogens (Methanolinea) was up to 62.6% of total archaeal sequences. Fe3O4 NPs addition would accelerate electrons transfer from acids oxidizers to syntrophic methanogenesis, further stimulate acids oxidizers to decompose acetate to H2/CO2, and finally facilitate more methane production.
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Affiliation(s)
- Dan Zhong
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin, 150090, China
| | - Jinxin Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin, 150090, China
| | - Wencheng Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin, 150090, China.
| | - Fengyue Qian
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin, 150090, China
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Çelebi EB, Aksoy A, Sanin FD. Effects of anaerobic digestion enhanced by ultrasound pretreatment on the fuel properties of municipal sludge. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:17350-17358. [PMID: 32157536 DOI: 10.1007/s11356-020-08230-4] [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: 10/16/2019] [Accepted: 02/25/2020] [Indexed: 06/10/2023]
Abstract
In this study, effects of ultrasound pretreatment on combustion characteristics and elemental composition of municipal sludge were examined for energy-based evaluation of sludge pretreatment. Waste activated sludge (WAS) from a municipal wastewater treatment plant was pretreated with ultrasound at varying durations and was subjected to anaerobic digestion in a biochemical methane potential (BMP) assay. Changes in gas production rates, calorific value (CV), elemental compositions, and ash contents of sludge samples were examined to assess the effects of pretreatment and digestion. Sonication at 0.73 W/mL enhanced gas production by 28%. Moreover, volatile solids (VS) and chemical oxygen demand (COD) removals increased from 41 to 45% and 33 to 37%, respectively. Following anaerobic digestion, CVs of samples decreased by about 18%. Sonicated samples exhibited a higher decrease. In order to quantify the change in overall energy content, total solids (TS) reduction was also taken into account. Loss was magnified as both CV and the amount of TS that would provide the overall energy were reduced. This loss was 38% for the control group and 41% for the 15 min sonicated sludge. Digestion decreased the C content of sludge by about 20% and H content by 50% due to biogas production. Ash content increased relatively as some of the combustible solids were lost due to digestion. Experimental results indicate that if sludge is to be combusted, digestion with or without ultrasound pretreatment may be disadvantageous if the aim is to maximize energy gain from sludge.
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Affiliation(s)
- Emrehan Berkay Çelebi
- Department of Environmental Engineering, Middle East Technical University, Ankara, 06800, Turkey
| | - Ayşegül Aksoy
- Department of Environmental Engineering, Middle East Technical University, Ankara, 06800, Turkey
| | - F Dilek Sanin
- Department of Environmental Engineering, Middle East Technical University, Ankara, 06800, Turkey.
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