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Shao M, Zhang C, Chen Q, Wu H, Dong Z, Bai X, Wang N, Xu Q. Hydrothermal-enhanced pyrolysis for efficient NO X reduction and biochar valorization from food waste digestate. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 183:112-122. [PMID: 38739988 DOI: 10.1016/j.wasman.2024.05.007] [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: 12/15/2023] [Revised: 04/26/2024] [Accepted: 05/08/2024] [Indexed: 05/16/2024]
Abstract
Pyrolysis has emerged as a promising technology for valorizing digestate resulting from the anaerobic digestion of food waste. However, the high NOX emissions during pyrolysis limit its application. This study proposed a hydrothermal coupled pyrolysis process to control the element transfer in digestate during biochar production. The efficient reduction of NOX emissions and the improvement of biochar adsorbability were realized. The hydrothermal process reduced the nitrogen content in solid digestate by 49.10 %-81.79 %, thus reducing the NOX precursors in syngas and the N-containing substances in bio-oil. Additionally, the specific surface area and the total pore volume of biochar were enhanced from 25 m2/g to 60-73 m2/g and 0.06 cm3/g to 0.12-0.14 cm3/g, respectively. More defects, oxygen-containing functional groups, and doped Ca on the biochar resulted in a high phosphate removal efficiency of 94 %. The proposed technology provides an efficient and environmentally friendly way to utilize the digestate.
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Affiliation(s)
- Mingshuai Shao
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Chao Zhang
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Qindong Chen
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Huanan Wu
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Zihang Dong
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Xinyue Bai
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Ning Wang
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China
| | - Qiyong Xu
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, Nanshan District, Shenzhen, 518055, PR China.
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2
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Liu Z, Luo F, He L, Wang S, Wu Y, Chen Z. Physical conditioning methods for sludge deep dewatering: A critical review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 360:121207. [PMID: 38788408 DOI: 10.1016/j.jenvman.2024.121207] [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: 01/22/2024] [Revised: 04/17/2024] [Accepted: 05/18/2024] [Indexed: 05/26/2024]
Abstract
Sludge is an inevitable waste product of sewage treatment with a high water content and large volume, it poses a significant threat of secondary pollution to both water and the atmosphere without proper disposal. In this regard, dewatering has emerged as an attractive method in sludge treatment, as it can reduce the sludge volume, enhance its transportability and calorific value, and even decrease the production of landfill leachate. In recent years, physical conditioning methods including non-chemical conditioners or energy input alone, have been extensively researched for their potential to enhance sludge dewatering efficiency, such as thermal treatment, freeze-thaw, microwave, ultrasonic, skeleton builders addition, and electro-dewatering, as well as combined methods. The main objective of this paper is to comprehensively evaluate the dewatering capacity of various physical conditioning methods, and identify key factors affecting sludge dewatering efficiency. In addition, future research anticipated directions and outlooks are proposed. This work is expected to provide valuable insights for developing efficient, eco-friendly, and low-energy consumption techniques for deep sludge dewatering.
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Affiliation(s)
- Zhuo Liu
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Fang Luo
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Lingzhi He
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Siqi Wang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yi Wu
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhuqi Chen
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
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3
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Chen R, Dai X, Dong B. Two birds with one stone: The multiple roles of hydrothermal treatment in dewatering municipal sludge and producing value-added products. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 896:165072. [PMID: 37364842 DOI: 10.1016/j.scitotenv.2023.165072] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/20/2023] [Accepted: 06/20/2023] [Indexed: 06/28/2023]
Abstract
Sludge dewatering and resource recovery are key steps in the sustainable treatment of municipal sludge (MS) owing to the high levels of moisture and nutrients. Among the treatment options available, hydrothermal treatment (HT) is promising to efficiently improve dewaterability and recover biofuels, nutrients, and materials from MS. However, hydrothermal conversion at different HT conditions generates multiple products. Integrating the characteristics of dewaterability and value-added products under different HT conditions facilitates the application of HT for the sustainable management of MS. Therefore, a comprehensive review of HT for its multiple roles in MS dewatering and value-added resource recovery is conducted. First, the impact of HT temperature on sludge dewaterability and key mechanisms are summarized. Then, this study elucidates the characteristics of biofuels produced (combustible gases, hydrochars, biocrudes, and H2-rich gases), nutrient recovery (proteins and phosphorus), and value-added materials under a wide range of HT conditions. Importantly, along with the integration and evaluation of HT product characteristics under different HT temperatures, this work proposes a conceptual sludge treatment system that integrates the different value-added products in different HT stages. Furthermore, a critical evaluation of the knowledge gaps in the HT for sludge deep dewatering, biofuels, nutrients, and materials recovery is provided along with recommendations for further research.
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Affiliation(s)
- Renjie Chen
- School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
| | - Xiaohu Dai
- School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Bin Dong
- School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China; YANGTZE Eco-Environment Engineering Research Center, China Three Gorges Corporation, Beijing 100038, PR China.
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4
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Wang G, Shu Q, Zhu Y, Liu Y, Yang X, Wu D, Sun H. Enhanced disintegration mechanism of surplus activated sludge to improve dewatering by thermally activated persulfate oxidation under mild temperature. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:106687-106697. [PMID: 37853646 DOI: 10.1007/s11356-023-29873-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 09/10/2023] [Indexed: 10/20/2023]
Abstract
The dewatering treatment is an essential process for the treatment and disposal of surplus activated sludge (SAS), and improving sludge dewatering performance is still a challenge and has become a research hotspot in recent years. The oxidation and disintegration of bacterial cells and extracellular polymeric substances (EPS) by active radicals produced by advanced oxidation processes (AOPs) were extremely promising to achieve deep sludge dewatering. This paper systematically studied the efficiency and mechanism of thermally activated persulfate (TAP) oxidation technology to the improvement of SAS dewatering performance. The results showed that the relative filterability (CST0/CST) was increased 2.52 times with 2.0 mmol/g VSS potassium peroxydisulfate (PDS) at 80 °C in 90 min. Under this condition, the Zeta potential of SAS significantly decreased from - 14.8 to - 1.44 mV, while the average particle size (dp50) decreased from 52.981 to 48.259 μm. Thermal treatment disrupted the sludge structure to release large amounts of EPS including polysaccharides and protein. Meanwhile, the results of three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectra showed that the TAP treatment could expedite the disintegration of sludge, facilitating the decrease of total EPS content and conversion of tightly bound EPS (TB-EPS) to loosely bound EPS (LB-EPS) and soluble EPS (S-EPS). The mechanism of TAP process to improve SAS dewatering performance was revealed, which could contribute to breaking the bottleneck of sludge depth dewatering and provide a theoretical and technical basis for its practical application.
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Affiliation(s)
- Gang Wang
- School of Environmental and Material Engineering, Yantai University, Yantai, 264005, China
| | - Quancheng Shu
- School of Environmental and Material Engineering, Yantai University, Yantai, 264005, China
| | - Yuliang Zhu
- School of Civil Engineering, Yantai University, Yantai, 264005, China
| | - Yucan Liu
- School of Civil Engineering, Yantai University, Yantai, 264005, China
| | - Xiaoyong Yang
- School of Environmental and Material Engineering, Yantai University, Yantai, 264005, China
| | - Daishun Wu
- Fujian Provincial Key Laboratory of Coastal Basin Environment, School of Marine and Biochemical Engineering, Fujian Polytechnic Normal University, Fuqing, 350300, China
| | - Hongwei Sun
- School of Environmental and Material Engineering, Yantai University, Yantai, 264005, China.
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Verbovskyi O, Zhuk V, Orel V, Popadiuk I. Optimization of the process of decreasing the filtration resistance of sewage sludge by thermal pretreatment: a case study for the Lviv WWTP. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2023; 88:1688-1698. [PMID: 37830991 PMCID: wst_2023_317 DOI: 10.2166/wst.2023.317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
The article presents the results of an experimental study of the effect of high-temperature thermal pretreatment on the specific resistance to filtration (SRF) of the sewage sludge (SS) from the Lviv wastewater treatment plant (WWTP), which is a combination of primary sludge and excess-activated sludge collected in primary sedimentation tanks. The kinetics of SRF reduction over time at temperatures of 140 - 150 °С are described by simple exponents, while at temperatures of 160 - 170 °С, they are described by modified two-parameter exponents. The study analyzed the dimensionless optimization function, which is the product of the final relative SRF of the sludge and the dimensionless time of thermal pretreatment. An optimal dimensionless thermal pretreatment time of 4.1 tr.0/2 was determined, and an empirical exponential equation for the time of SRF reduction by twice tr.0/2 was derived. Based on the analysis, it was found that the highest efficiency in reducing the SRF of Lviv WWTP SS occurs at a temperature of 170 °C and an optimal duration of thermal pretreatment of 55 min.
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Affiliation(s)
- Orest Verbovskyi
- Institute of Civil Engineering and Building Systems, Lviv Polytechnic National University, 12, S. Bandery Str., Lviv 79013, Ukraine E-mail:
| | - Volodymyr Zhuk
- Institute of Civil Engineering and Building Systems, Lviv Polytechnic National University, 12, S. Bandery Str., Lviv 79013, Ukraine
| | - Vadym Orel
- Institute of Civil Engineering and Building Systems, Lviv Polytechnic National University, 12, S. Bandery Str., Lviv 79013, Ukraine
| | - Ihor Popadiuk
- Institute of Civil Engineering and Building Systems, Lviv Polytechnic National University, 12, S. Bandery Str., Lviv 79013, Ukraine
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6
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Guo Z, Ma L, Dai Q, Liu Y, Zhang D, Ao R. Behavior of heavy metals in municipal sludge during dewatering: The role of conditioners and extracellular polymeric substances. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 342:118287. [PMID: 37269725 DOI: 10.1016/j.jenvman.2023.118287] [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: 10/23/2022] [Revised: 05/23/2023] [Accepted: 05/26/2023] [Indexed: 06/05/2023]
Abstract
Heavy metals, the main harmful substances in the sludge, are easily enriched, have adverse effects on the treatment and disposal of the sludge. In this study, two conditioners (modified corn-core powder, MCCP, and sludge-based biochar, SBB) were separately added and jointly added into municipal sludge to enhance sludge dewaterability. Meanwhile, diverse organics, such as extracellular polymeric substances (EPS), were released under pretreatment. The different organics had different effects on each heavy metal fraction and changed the toxicity and bioavailability of the treated sludge. The exchangeable fraction (F4) and carbonate fraction (F5) of heavy metal were nontoxic and nonbioavailable. When MCCP/SBB was used to pretreat the sludge, the ratio of metal-F4 and -F5 decreased, indicating that MCCP/SBB reduced the biological availability and ecological toxicity of the heavy metals in the sludge. These results were consistent with the calculation of the modified potential ecological risk index (MRI). To understand the detailed function of organics in the sludge network, the relationship between EPS, the secondary structure of the protein, and heavy metals was analyzed. The analyses revealed that the increasing proportion of β-sheet in soluble EPS (S-EPS) generated more active sites in the sludge system, which enhanced the chelate or complex function among organics and heavy metals, thus reducing the migration risks.
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Affiliation(s)
- Zhiying Guo
- College of Biological and Agricultural Sciences, Honghe University, Mengzi, 661199, Yunnan, China
| | - Liping Ma
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, Yunnan, China.
| | - Quxiu Dai
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, Yunnan, China.
| | - Yanhong Liu
- College of Biological and Agricultural Sciences, Honghe University, Mengzi, 661199, Yunnan, China
| | - Degang Zhang
- College of Biological and Agricultural Sciences, Honghe University, Mengzi, 661199, Yunnan, China
| | - Ran Ao
- College of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang, 550025, China
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7
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Liu H, Dong L, Zhang X, Zhao C, Shi M, Li Y, Liu H. Activated sludge thermal hydrolysis for liquid fermentation to produce VFAs: Exploring the balance of carbon release between quantity, quality and recovery. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 322:115976. [PMID: 36041300 DOI: 10.1016/j.jenvman.2022.115976] [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: 05/06/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Thermal hydrolysis has been widely applied to improve organics bioconversion during sludge anaerobic treatment currently, based on which, liquid fermentation to produce volatile fatty acids (VFAs) with high concentration and good purity has been successfully developed by only using hydrolysate as the substrate to avoid the interference of "useless" residual solids. Therefore, obtaining high-quality hydrolysate is the prerequisite for VFAs production via liquid fermentation. However, previous studies on sludge thermal hydrolysis either only focused on organics release or only on sludge dewatering. Actually, the quantity, quality and recovery of the carbon released from sludge are equally important, and a balance between them should be established. Results in the present study indicated that organics concentration in sludge hydrolysate could not be arbitrarily enhanced by increasing thermal hydrolysis intensity or sludge concentration, and interestingly there seemed a threshold of around 32 g/L that the highest concentration the sludge hydrolysate could reach. Moreover, with the increase of hydrolysis intensity, the bioavailability of sludge could be promoted but reached the maximum with BOD5/COD of around 0.44 at 180 °C, while sludge dewaterability could be improved but also trended to stable after 160 °C. The findings of this study demonstrate that excessively high hydrolysis intensity would not only waste energy but also induce forms of non-biodegradable organics. The performances of sludge liquid fermentation, including VFAs production and sludge reduce, were closely related to hydrolysis intensity, the choice of which should be based on the balance of the quantity, quality and recovery of the released carbon.
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Affiliation(s)
- Hongbo Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China; Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou University of Science and Technology, Suzhou 215011, Jiangsu Province, PR China.
| | - Lu Dong
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China
| | - Xuedong Zhang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China
| | - Cheng Zhao
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China
| | - Mingze Shi
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China
| | - Yajie Li
- Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou University of Science and Technology, Suzhou 215011, Jiangsu Province, PR China
| | - He Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China; Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou University of Science and Technology, Suzhou 215011, Jiangsu Province, PR China.
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8
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Li X, Xiao X, Liu Y, Fang G, Wang P, Zou D. Analysis of organic matter conversion behavior and kinetics during thermal hydrolysis of sludge and its anaerobic digestion performance. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 305:114408. [PMID: 34974216 DOI: 10.1016/j.jenvman.2021.114408] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
In thermal hydrolysis (TH) of waste activated sludge (WAS), the material transformation of a specific temperature heating for a set duration is generally examined. However, this study looked at the material changes of TH as the temperature rose (90-210 °C) and the kinetic derivation of soluble chemical oxygen demand (SCOD), protein, and carbohydrate using the Coats-Redfern model. It was found that the proportion of soluble protein and soluble carbohydrate in the organic components and their contents reached the maximum (17.39 and 8.10 g L-1 respectively) at 180 °C. Differently, volatile fatty acid (VFA), amino acids, and ammonia nitrogen increased with the TH temperature and reached a maximum at 210 °C. The fitting equations of non-isothermal dynamics at the medium- and low-temperature stages (90-180 °C) at n = 1, 0.5, and 2 were studied. When n = 1, the activation energies of COD, protein, and carbohydrate were 33.32, 23.34, and 36.15 kJ mol-1, respectively. And the kinetic analysis results were in good agreement with the experimental results (the maximum rate of increase in protein and carbohydrate was at 135-150 °C and 150-180 °C, respectively). Moreover, the pattern of anaerobic digestion performance of WAS was comparable to the trend of protein and carbohydrate in TH, the highest cumulative methane production was 159.68 mL·g-1VS for the TH sludge at 180 °C. This study provided a theoretical foundation for the use of thermal hydrolysis in engineering.
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Affiliation(s)
- Xinxin Li
- Department of Environmental Science & Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Xiong Xiao
- Department of Environmental Science & Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Yanping Liu
- Department of Environmental Science & Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
| | - Gang Fang
- Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Pingbo Wang
- Department of Environmental Science & Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Dexun Zou
- Department of Environmental Science & Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
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9
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Ebrahimi M, Dunn K, Li H, Rowlings DW, O'Hara IM, Zhang Z. Effect of hydrothermal treatment on deep dewatering of digested sludge: Further understanding the role of lignocellulosic biomass. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 810:152294. [PMID: 34906581 DOI: 10.1016/j.scitotenv.2021.152294] [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: 11/09/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
In this study, lignocellulose-assisted hydrothermal treatment (HTT) of digestated sludge was studied to further understand the role of biomass in HTT and its effect on subsequent sludge dewatering. HTT of sludge-biomass mixtures at 180 °C for 60 min at a sludge/biomass total solids (TS) ratio of 1:1 led to solid residue moistures of 36%-40% after dewatering using a hydraulic press at 24 MPa, compared to 69.5% without biomass. Further investigation showed that organic acids, especially acetic acid generated from lignocellulosic biomass hydrolysed extracellular polymeric substances (EPS), especially EPS-protein, and improved sludge dewaterability. The role of organic acids was further verified with the addition of 10.0 g/L acetic acid for HTT of sludge at 180 °C in the absence of biomass. It was also observed that in HTT of sludge with 10.0 g/L acetic acid, protein nitrogen was converted to more stable forms of nitrogen such as pyrrole‑nitrogen and quaternary‑nitrogen. However, HTT with acetic acid alone resulted in dewatered solids with high ash contents, which may limit their applications as soil amendments. Combination of biomass and acetic acid with a sludge/biomass TS ratio of 3:1 and acetic acid loading of 10.0 g/L at a HTT temperature of 180 °C for 60 min led to solid moistures of 50.5% with hardwood sawdust and 57.7% with sugarcane bagasse after dewatering at 3 MPa, corresponding to total weight reductions of 66.3% and 55.7%, respectively. In contrast, HTT of sludge at 180 °C for 60 min without acetic acid and biomass resulted in a solid moisture of 76.6% after dewatering at 3 MPa and a corresponding weight reduction of 49.5%. With the use of biomass and acetic acid in HTT, the treated and dewatered solids also had increased carbon content and reduced ash content. These dewatered solids may be used as potential soil amendments though the properties related to soil applications need to be considered in future studies.
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Affiliation(s)
- Majid Ebrahimi
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia
| | - Kameron Dunn
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia
| | - Huan Li
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - David W Rowlings
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia; School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia
| | - Ian M O'Hara
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia
| | - Zhanying Zhang
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia.
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10
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Zhang C, Shao M, Wu H, Wang N, Wang X, Wang Q, Xu Q. Mechanism insights into hydrothermal dewatering of food waste digestate for products valorization. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 804:150145. [PMID: 34517326 DOI: 10.1016/j.scitotenv.2021.150145] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 06/13/2023]
Abstract
Poor dewaterability is a bottleneck of the disposal of digestate from food waste (DFW). However, the dewatering mechanism remains unclear due to the complex composition of DFW. Understanding the dewatering mechanism, as well as the transformation of organic/inorganic matters is essential for the DFW management and valorization. In this study, the distribution, transformation, and complex interplay of organic and inorganic matters at different Hydrothermal treatment (HTT) temperatures were comprehensively analyzed to explore the hydrothermal dewatering mechanism of DFW. When HTT was conducted in the temperature range of 120-180 °C, the interstitial water was released as surface or free water because of membrane breaking and size reduction of the solid substrate. Releasing divalent cations increased the Zeta potential of the bulk solution. The weaker electrostatic repulsion between suspended particles made them easier to settle as the centrifugation cake. When the temperature of HTT was above 180 °C, polymerization and aromatization reactions took place gradually for organic matters, and the bound water was further removed. The generated humic substances were more hydrophobic than the raw material. In addition, the humic substance could combine with cationic metals, which decreased the zeta potential of the bulk solution but promoted the aggregation of nanoparticles and enhance the dewaterability of DFW.
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Affiliation(s)
- Chao Zhang
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China
| | - Mingshuai Shao
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China
| | - Huanan Wu
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China
| | - Ning Wang
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China
| | - Xue Wang
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China
| | - Qian Wang
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China
| | - Qiyong Xu
- Shenzhen Engineering Laboratory for Eco-efficient Recycled Materials, School of Environment and Energy, Peking University Shenzhen Graduate School, University Town, Nanshan District, Shenzhen 518055, PR China.
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Zhang W, Dong B, Dai X, Dai L. Enhancement of sludge dewaterability via the thermal hydrolysis anaerobic digestion mechanism based on moisture and organic matter interactions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 798:149229. [PMID: 34325135 DOI: 10.1016/j.scitotenv.2021.149229] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/20/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
It is known that sludge dewaterability improves during the thermal hydrolysis process (THP); however, the effect of thermal hydrolysis and anaerobic digestion (THP-AD) on sludge dewaterability is unclear. Further, the difference between thermal hydrolysis as pre-treatment for anaerobic digestion (pre-THP-AD) and as post-treatment (post-THP-AD) is also unclear. Based on the evolution of the interaction between organic matter and moisture, the mechanism of pre-THP-AD and post-THP-AD improving the sludge dewaterability was explored. The capillary suction time values of pre-THP-AD and post-THP-AD increased by 58% and 59%, respectively, and the proportion of free moisture increased by 10.44% and 10.59%, respectively, compared with the conventional anaerobic digestion (CAD) process. The cell structure was destroyed and most organic matter was converted into dissolved form through THP, organic matter degraded during AD, the interaction between moisture and organic matter declined, and the mechanically bound moisture transformed into free moisture. Additionally, the intensity of hydrophilic functional groups, such as amide I decreased and amide II disappeared after (pre- and post-) THP-AD. The surface hydrophobicity of sludge samples was enhanced and sludge dewaterability improved. The mechanism of pre-/post-THP-AD enhanced sludge dewaterability based on the interaction between moisture and organic matter; additionally, this will provide a reference for optimised moisture-sludge separation processes and guidance for the optimisation of engineering operation parameters.
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Affiliation(s)
- Wei Zhang
- School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, PR China
| | - Bin Dong
- School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Xiaohu Dai
- School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
| | - Lingling Dai
- School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
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Dutta S, He M, Xiong X, Tsang DCW. Sustainable management and recycling of food waste anaerobic digestate: A review. BIORESOURCE TECHNOLOGY 2021; 341:125915. [PMID: 34523582 DOI: 10.1016/j.biortech.2021.125915] [Citation(s) in RCA: 110] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/03/2021] [Accepted: 09/04/2021] [Indexed: 05/28/2023]
Abstract
Anaerobic digestion (AD) is a widely used technology to valorise food waste for biogas production yet a considerable amount of digestate remains under-utilised. Sustainable management and recycling of the nutrient-rich food waste anaerobic digestate (FWD) is highly desirable for closing resource loop and actualising circular economy. This work reviews the distinct properties of FWD and the existing treatment technologies. FWD shows great prospects as a nutrient source for microalgal cultivation and biofuel production. Emerging technologies such as thermal conversion (e.g., pyrolysis and hydrothermal treatment) of FWD into value-added products such as functionalised biochar/hydrochar with diverse applications would be attractive and warrant further research investigation. Integrated AD with subsequent valorisation facilities is highly encouraged to achieve complete utilisation of resources and reduce carbon emissions.
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Affiliation(s)
- Shanta Dutta
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Mingjing He
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Xinni Xiong
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
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Qiu C, Xu W, Wang Y, Yang J, Su X, Lin Z. Hydrothermal alkaline conversion of sewage sludge: optimization of process parameters and characterization of humic acid. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:57695-57705. [PMID: 34091839 DOI: 10.1007/s11356-021-14711-x] [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: 02/10/2021] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
Sewage sludge (SS) dewatering is a key step in sludge disposal, which plays an important role in reducing sludge volume, facilitating transportation and subsequent treatment. In this paper, a facile hydrothermal-alkaline treatment for SS was proposed, which can be used for sludge dewatering and humic acid (HA) recycling at the same time. Response surface methodology (RSM) was used to determine the optimal conditions, and a mathematical model was established to accurately predict the changes of sludge water content and the extraction rate of HA. Under the optimal conditions of 170 °C/42 min/0.05 (for hydrothermal temperature, hydrothermal time, and mass ratio of KOH to wet sludge, respectively), the water content decreased to 46.7% and the extraction rate of HA (with a purity of 96.2%) was 89.1%. The improvement of the dewatering performance effectively facilitates the subsequent disposal of the sludge. The hydrothermal-alkaline method not only realizes the efficient dehydration of the sludge, but also obtains HA from the sludge extract. The obtained HA has potential economic value in the fields of agriculture, biological medicine, environment, and the like.
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Affiliation(s)
- Chen Qiu
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong, 510006, People's Republic of China
- China-Singapore International Joint Research Institute, Guangzhou, 510000, People's Republic of China
| | - Wenbing Xu
- Dongjiang Environmental Company Limited, Shenzhen, Guangdong, 518057, People's Republic of China
| | - Yanjie Wang
- Dongjiang Environmental Company Limited, Shenzhen, Guangdong, 518057, People's Republic of China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China
| | - Xintai Su
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong, 510006, People's Republic of China.
- China-Singapore International Joint Research Institute, Guangzhou, 510000, People's Republic of China.
| | - Zhang Lin
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong, 510006, People's Republic of China
- China-Singapore International Joint Research Institute, Guangzhou, 510000, People's Republic of China
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