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Xiao K, Lv Y, Yu W, Yang J. Visualization of water transfer channel in sludge dewatering conditioned with skeleton builders by X-ray micro-computed tomography. CHEMOSPHERE 2024; 355:141818. [PMID: 38548085 DOI: 10.1016/j.chemosphere.2024.141818] [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: 01/07/2024] [Revised: 03/05/2024] [Accepted: 03/25/2024] [Indexed: 04/18/2024]
Abstract
Skeleton builders were normally deemed to improve the high porosity and newly-generated permeability of sludge cakes by building water transfer channel during high pressure filtration, thus enhancing sludge dewaterability. However, currently a direct visualization proof of water transfer channel was still lacking. This study provided the direct proof for visualizing water transfer channel in dewatered sludge cakes conditioned with a typical skeleton builder (i.e., phosphogypsum (PG)) by X-ray micro-computed tomography (micro-CT) for the first time. After the addition of PG, the pixel value and image luminance increased significantly, indicating the presence of high density substances from both two-dimensional (2D) cross section and three-dimensional (3D) reconstruction CT images. Moreover, the CT numbers showed strong and negative correlations with specific resistance to filtration (SRF) (R = - 0.99, p < 0.05), capillary suction time (CST) (regression coefficient (R) = - 0.87, probability (p) < 0.05), and water content of the dewatered sludge cake (R = - 0.99, p < 0.05), respectively. These results indicated that the X-ray micro-CT could be a potential technique for analyzing the water distribution in sludge samples conditioned with skeleton builders.
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Affiliation(s)
- Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Environmental Science and Engineering Program, Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong, 515063, China
| | - Yang Lv
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, 8 Jiangwangmiao Street, Nanjing, Jiang Su, 210042, China
| | - Wenbo Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Water Quality Safety and Water Pollution Control Engineering Center, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China.
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2
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He X, He L, Lin Z, Zhou J, Shi S, Liu Y, Zhou J. Deep dewatering of activated sludge using composite conditioners of surfactant, acid and flocculant: The mechanism and dosage model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150899. [PMID: 34656594 DOI: 10.1016/j.scitotenv.2021.150899] [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: 07/21/2021] [Revised: 10/05/2021] [Accepted: 10/05/2021] [Indexed: 06/13/2023]
Abstract
To address the problem of difficult disposal caused by poor dewaterability of high-organic sludge in wastewater treatment plant, this study developed a sludge composite conditioner (SCC) consisting of sodium dodecyl sulfate (SDS), HCl and FeCl3. It has the potential to significantly improve the dewaterability of the high-organic sludge with the VSS/MLSS of 80%. The moisture content (MC) and bound water content of sludge were reduced from 98.00 to 59.65% and from 3.42 to 0.91 g/g dry sludge (DS) after being conditioned, respectively. The surfactant (SDS) promoted the dissolution of extracellular polymeric substances (EPS). The acid (HCl) enhanced the decomposition of the sludge flocs, making the insoluble EPS peel off and turn into the liquid phase. As a result, total EPS decreased by 52.70% compared to the original sludge. In addition, due to the neutralization effect of protons and FeCl3, the Zeta potential increased remarkably from -13.80 mV to -1.72 mV and the dispersed sludge particles formed during EPS dissolution process were re-flocculated, which increased the average size of the sludge particles. The ratio of proteins (PN)/polysaccharides (PS) also increased from 1.69 to 3.81. And a quantitative model of optimum dosage of SCC agents based on the influence of the sludge PS, PN and EPS content has been established, aiming to determine the dosage of each conditioner according to the properties of target sludge. In general, the SCC provided an effective pathway for sludge deep dewatering.
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Affiliation(s)
- Xuejie He
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Lei He
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Ziyuan Lin
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Jiong Zhou
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Shuohui Shi
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Yi Liu
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Jian Zhou
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
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3
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Hu P, Shen S, Zhao D, Wei H, Ge J, Jia F, Zhang X, Yang H. The influence of hydrophobicity on sludge dewatering associated with cationic starch-based flocculants. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 296:113218. [PMID: 34246906 DOI: 10.1016/j.jenvman.2021.113218] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/25/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Coagulation/flocculation is an extensive and effective pretreatment technology for improving the sludge dewaterability. A series of hydrophobically associated cationic starch-based flocculants (CS-DMRs) with different degrees of hydrophobicity but similar charge densities were designed and synthesized. The CS-DMRs exhibited excellent sludge dewatering performance. The dewaterability of sludge increased with the hydrophobicity of the CS-DMRs, and the filter cake moisture content (FCMC) and specific resistance to filtration (SRF) could be reduced from 95.47% and 7.09 × 1012 m/kg to 79.26% and 2.258 × 1012 m/kg, respectively, at a constant pressure of 0.05 MPa after conditioned by the starch-based flocculant with the highest hydrophobicity at its optimal dose. Moreover, due to their amphiphilic structures, CS-DMRs could closely interact with the negatively charged extracellular polymeric substances (EPS), efficiently compress the protein and polysaccharide in EPS, and release the bound water. A second-order polynomial model was proposed according to the phenomenological theory to quantitatively analyze the effect of hydrophobicity in these starch-based flocculants on the sludge dewaterability. The structure-activity relationship was built, and the optimal dose and corresponding FCMC could be theoretically estimated accordingly. The results were in good agreement with the experimental results. The dewatering mechanisms were also discussed in detail on the basis of the changes in the FCMC, SRF, capillary suction time, properties of sludge flocs, compression coefficient, microstructures of sludge cakes, EPS fractions and components, and spatial distributions of the proteins and polysaccharides. In addition to charge neutralization, the hydrophobic association effects of CS-DMRs played an important role in the formation of drainage channels and net-like porous structures in the sludge cake to improve its permeability and filterability. This study thus provided a good understanding of the structural effects of the starch-based flocculants on the sludge dewaterability. The results are greatly beneficial to the fabrication and utilization of environment-friendly and high-performance natural polymeric conditioners for sludge treatment.
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Affiliation(s)
- Pan Hu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Shaohang Shen
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Donghua Zhao
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Hua Wei
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Jun Ge
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Feiyue Jia
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Xiangxiang Zhang
- Shanghai Waterway Engineering Design and Consulting Co., LTD., Shanghai, 200120, PR China
| | - Hu Yang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Quanzhou Institute for Environmental Protection Industry, Nanjing University, Beifeng Road, Quanzhou, 362000, PR China.
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4
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Ranjbar F, Karrabi M, Danesh S, Gheibi M. Improvement of wastewater sludge dewatering using ferric chloride, aluminum sulfate, and calcium oxide (experimental investigation and descriptive statistical analysis). WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2021; 93:1138-1149. [PMID: 33522044 DOI: 10.1002/wer.1526] [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: 09/27/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 06/12/2023]
Abstract
In this research, application of chemical conditioners for the conditioning of sludge and their effects on the improvement of sludge thickening of the wastewater treatment plant in the city of Bojnourd (Iran) is investigated. The concentration of chemical conditioners, pH and coagulation and flocculation time is from among the parameters studied in this research work. The results obtained indicate that sludge volume reduction for the chemical conditioners used, including Ferric Chloride (FeCl3 ), Aluminum Sulfate (Al2 (SO4 )3 ), and Calcium Oxide (CaO) are 41, 17, and 33 percent, respectively. The optimal concentration for FeCl3 , Al2 (SO4 )3, and CaO are 550, 1100, and 292 mg/L, respectively, and the optimal values of pH are 9, 7.5, and 10, respectively. The time to filtration (TTF) and reduction in sludge moisture content (SMC) for Ferric Chloride, Aluminum Sulfate, and Calcium Oxide are 45 s and 6.2%, 135 s and 3.3%, 190 s and 2.4% respectively. PRACTITIONER POINTS: Investigating the sludge conditioning by Ferric Chloride, Aluminum Sulfate, and Calcium Oxide. Determining the optimal concentration, pH, and coagulation/flocculation time. Calculating the time to filtration (TTF) and reduction in sludge moisture content (SMC). Predicting the settled sludge volume using descriptive statistical analysis.
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Affiliation(s)
- Flora Ranjbar
- Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Mohsen Karrabi
- Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Shahnaz Danesh
- Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Mohammad Gheibi
- Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
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5
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Ge D, Xiao J, Bian C, Yuan H, Zhu N. Exploring the efficacy and mechanism of tannic acid/Fe3+ conditioning for enhancing waste activated sludge dewaterability. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116643] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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6
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Jia H, Liu B, Zhang X, Chen J, Ren W. Effects of ultrasonic treatment on the pyrolysis characteristics and kinetics of waste activated sludge. ENVIRONMENTAL RESEARCH 2020; 183:109250. [PMID: 32088608 DOI: 10.1016/j.envres.2020.109250] [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: 11/28/2019] [Revised: 01/17/2020] [Accepted: 02/11/2020] [Indexed: 06/10/2023]
Abstract
In this study, physicochemical analysis, thermogravimetric analysis, and kinetic analysis were used to investigate the effects of ultrasonic treatment on waste activated sludge (WAS), with emphasis on its kinetic parameters and pyrolysis behaviors. Thermogravimetric analysis results indicated that the pyrolysis of ultrasonic WAS might be divided into three stages. The main pyrolysis behavior occurred in the second stage (180-540 °C), and its pyrolysis behavior and activation energy were similar to the thermal decomposition of lignocellulosic biomass. Moreover, the physicochemical analysis indicated that ultrasonic treatment reduced the content of lignocellulose and ash, thus changing the pyrolysis characteristics of WAS. Ultrasonic WAS exhibited a higher residual weight (54.93 wt%), a larger average activation energy (140.09 kJ/mol), a lower maximum weight loss rate (-5.71%/min), and a change in the weight loss peak to a higher temperature (304.7 °C), reflecting the decrease of the pyrolysis reaction rate. In addition, the kinetic parameters were calculated using the Starink method and Coats-Redfern method.
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Affiliation(s)
- Hongyu Jia
- College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang west road, Huangdao district, Qingdao City, 266580, China
| | - Bingkun Liu
- College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang west road, Huangdao district, Qingdao City, 266580, China
| | - Xiuxia Zhang
- College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang west road, Huangdao district, Qingdao City, 266580, China.
| | - Jie Chen
- College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang west road, Huangdao district, Qingdao City, 266580, China
| | - Wenhai Ren
- College of Chemical Engineering, China University of Petroleum (East China), 66 Changjiang west road, Huangdao district, Qingdao City, 266580, China
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7
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Ge D, Yuan H, Shen Y, Zhang W, Zhu N. Improved sludge dewaterability by tannic acid conditioning: Temperature, thermodynamics and mechanism studies. CHEMOSPHERE 2019; 230:14-23. [PMID: 31102867 DOI: 10.1016/j.chemosphere.2019.05.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/15/2019] [Accepted: 05/04/2019] [Indexed: 06/09/2023]
Abstract
Waste activated sludge (WAS), containing biological pathogens, chemical elements and high moisture (>99%), was generated continually from municipal sewage treatment plants. Sludge dewatering could diminish the volume of WAS and control the diffusion of environmental pollution efficiently. In this study, tannic acid (TA), as a plant-derived phenolic compound, was investigated for improving WAS dewaterability at different temperatures. Apparently, the WAS dewaterability was enhanced by TA conditioning in the range of 25-55 °C, but further increase in temperature did not significantly affect the dewatering. With the TA addition of 0.15 mmol/gTS (total solid) at 55 °C, the WAS dewaterability was improved by 84.5% decrease in capillary suction time (CST), 96.5% decrease in specific resistance of filtration (SRF), and 19.9% decrease in water content (Wc) of dewatered sludge cake. TA facilitated removing supernatant viscosity and protein of sludge EPS (extracellular polymeric substances), specifically with 88.9% and 75.0% protein removal of slime EPS (S-EPS) and loosely bound EPS (LB-EPS). Thermodynamics modeling revealed that the improved dewaterability was dominantly attributed to the hydrophobic bonding between TA and EPS proteins, which was strengthened with the increase in temperature. However, when the conditioning temperature exceeded 55 °C, thermal effect took place and accelerated the release of biopolymers into EPS and hence, counteracted the beneficial effect of TA conditioning to further improve WAS dewatering. The results offered not only the dewatering effectiveness and mechanism of TA conditioning, but also a potential approach of applying plant waste to treat WAS for the high dewaterability.
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Affiliation(s)
- Dongdong Ge
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Haiping Yuan
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yanwen Shen
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wenrui Zhang
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Nanwen Zhu
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
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8
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Ge D, Yuan H, Xiao J, Zhu N. Insight into the enhanced sludge dewaterability by tannic acid conditioning and pH regulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 679:298-306. [PMID: 31085410 DOI: 10.1016/j.scitotenv.2019.05.060] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 05/05/2019] [Accepted: 05/05/2019] [Indexed: 06/09/2023]
Abstract
Tannic acid (TA), a phenolic compound, may be considered as a sludge conditioning agent on account of its ability to precipitate protein. In this study, the effectiveness of TA conditioning on enhancing waste activated sludge (WAS) dewatering was investigated at various pH values. The results indicated that with the conditioning of 0.15 mmol TA per gram of total solid (TS), the WAS dewaterability was affected distinctly by the pH regulation. The reductions of 86.8% capillary suction time (CST), 96.3% specific resistance of filtration (SRF), and 23.6% water content (Wc) of dewatered sludge cake were achieved at an optimal pH value of 4.0. Meanwhile, obvious alterations were observed in some aspects like supernatant viscosity, zeta potential, particle size and extracellular polymeric substances (EPS) polymers. Correlation analysis indicated that the proteins in slime EPS and loosely bound EPS dominantly governed sludge dewaterability. Fluorescence quenching analysis indicated that in the range of acidity, the increase of pH value afforded more binding sites of sludge EPS for TA. However, the removal of EPS protein depended on the combined effect of TA conditioning and pH regulation. The findings provided a novel approach and explanation of WAS dewaterability enhancement using organic additive conditioning and pH regulation.
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Affiliation(s)
- Dongdong Ge
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Haiping Yuan
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jiamu Xiao
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Nanwen Zhu
- School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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9
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Pembroke JT, Ryan MP. Autothermal Thermophilic Aerobic Digestion (ATAD) for Heat, Gas, and Production of a Class A Biosolids with Fertilizer Potential. Microorganisms 2019; 7:E215. [PMID: 31349557 PMCID: PMC6722850 DOI: 10.3390/microorganisms7080215] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 11/17/2022] Open
Abstract
Autothermal thermophilic aerobic digestion (ATAD) is a microbial fermentation process characterized as a tertiary treatment of waste material carried out in jacketed reactors. The process can be carried out on a variety of waste sludge ranging from human, animal, food, or pharmaceutical waste where the addition of air initiates aerobic digestion of the secondary treated sludge material. Digestion of the sludge substrates generates heat, which is retained within the reactor resulting in elevation of the reactor temperature to 70-75 °C. During the process, deamination of proteinaceous materials also occurs resulting in liberation of ammonia and elevation of pH to typically pH 8.4. These conditions result in a unique microbial consortium, which undergoes considerable dynamic change during the heat-up and holding phases. The change in pH and substrate as digestion occurs also contributes to this dynamic change. Because the large reactors are not optimized for aeration, and because low oxygen solubility at elevated temperatures occurs, there are considerable numbers of anaerobes recovered which also contributes to the overall digestion. As the reactors are operated in a semi-continuous mode, the reactors are rarely washed, resulting in considerable biofilm formation. Equally, because of the fibrous nature of the sludge, fiber adhering organisms are frequently found which play a major role in the overall digestion process. Here, we review molecular tools needed to examine the ATAD sludge consortia, what has been determined through phylogenetic analysis of the consortia and the nature of the dynamics occurring within this unique fermentation environment.
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Affiliation(s)
- J Tony Pembroke
- Department of Chemical Sciences, School of Natural Sciences and Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland
| | - Michael P Ryan
- Department of Chemical Sciences, School of Natural Sciences and Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland.
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10
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Wang LF, Qian C, Jiang JK, Ye XD, Yu HQ. Response of extracellular polymeric substances to thermal treatment in sludge dewatering process. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 231:1388-1392. [PMID: 28911794 DOI: 10.1016/j.envpol.2017.08.119] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 08/04/2017] [Accepted: 08/31/2017] [Indexed: 06/07/2023]
Abstract
Sludge dewatering is an important process in municipal wastewater treatment and critically influences the subsequent transportation and disposal. Thermal treatment coupled with other chemical processes has been widely used to improve sludge dewaterability. However, information about the response of sludge extracellular polymeric substances (EPS) to thermal treatment and its role in sludge dewatering is still limited. In this work, the effects of thermal treatment on anaerobic and aerobic sludges were investigated with an emphasis on the colloid properties of released EPS in sludge dewatering process. The results indicate that sludge dewaterability became deteriorated with the increased temperature in the range of 30-170 °C, which was ascribed to the disintegration of sludge flocs and change of EPS characteristics. Disintegrated sludge induced the release of the negatively charged EPS, resulting in the weakened bridging interaction and lower compactness. After thermal treatment, the EPS with a higher average molecular weight and stretched coil configuration retained more water. In addition, difference in dewaterability between anaerobic and aerobic sludges was found to be attributed to their different contents and structures of EPS components. These results provide an insight into thermal-dependent sludge dewatering process and are useful to facilitate water-sludge separation.
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Affiliation(s)
- Long-Fei Wang
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, China
| | - Chen Qian
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, China
| | - Jian-Kai Jiang
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, China.
| | - Xiao-Dong Ye
- Department of Chemical Physics, University of Science & Technology of China, China
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, China
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11
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Wang LF, Wang LL, Li WW, He DQ, Jiang H, Ye XD, Yuan HP, Zhu NW, Yu HQ. Surfactant-mediated settleability and dewaterability of activated sludge. Chem Eng Sci 2014. [DOI: 10.1016/j.ces.2014.05.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Piterina AV, Pembroke JT. Use of PCR-DGGE Based Molecular Methods to Analyse Microbial Community Diversity and Stability during the Thermophilic Stages of an ATAD Wastewater Sludge Treatment Process as an Aid to Performance Monitoring. ISRN BIOTECHNOLOGY 2013; 2013:162645. [PMID: 25937969 PMCID: PMC4393042 DOI: 10.5402/2013/162645] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 08/20/2013] [Indexed: 01/07/2023]
Abstract
PCR and PCR-DGGE techniques have been evaluated to monitor biodiversity indexes within an ATAD (autothermal thermophilic aerobic digestion) system treating domestic sludge for land spread, by examining microbial dynamics in response to elevated temperatures during treatment. The ATAD process utilises a thermophilic population to generate heat and operates at elevated pH due to degradation of sludge solids, thus allowing pasteurisation and stabilisation of the sludge. Genera-specific PCR revealed that Archaea, Eukarya and Fungi decline when the temperature reaches 59°C, while the bacterial lineage constitutes the dominant group at this stage. The bacterial community at the thermophilic stage, its similarity index to the feed material, and the species richness present were evaluated by PCR-DGGE. Parameters such as choice of molecular target (16S rDNA or rpoB genes), and electrophoresis condition, were optimised to maximise the resolution of the method for ATAD. Dynamic analysis of microbial communities was best observed utilising PCR-DGGE analysis of the V6-V8 region of 16S rDNA, while rpoB gene profiles were less informative. Unique thermophilic communities were shown to quickly adapt to process changes, and shown to be quite stable during the process. Such techniques may be used as a monitoring technique for process health and efficiency.
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Affiliation(s)
- Anna V Piterina
- Department of Chemical and Environmental Sciences and the Material and Surface Science Institute (MSSI), University of Limerick, Limerick, Ireland
| | - J Tony Pembroke
- Department of Chemical and Environmental Sciences and the Material and Surface Science Institute (MSSI), University of Limerick, Limerick, Ireland
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13
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Cheng J, Wang L, Ji Y, Zhu N, Kong F. The influence of factors on dewaterability of one-stage autothermal thermophilic aerobically digested sludges. World J Microbiol Biotechnol 2013; 30:639-47. [DOI: 10.1007/s11274-013-1487-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/10/2013] [Indexed: 11/24/2022]
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14
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Piterina AV, Bartlett J, Pembroke JT. Phylogenetic analysis of the bacterial community in a full scale autothermal thermophilic aerobic digester (ATAD) treating mixed domestic wastewater sludge for land spread. WATER RESEARCH 2012; 46:2488-2504. [PMID: 22386327 DOI: 10.1016/j.watres.2012.01.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 12/15/2011] [Accepted: 01/28/2012] [Indexed: 05/31/2023]
Abstract
The bacterial community associated with a full scale autothermal thermophilic aerobic digester (ATAD) treating sludge, originating from domestic wastewater and destined for land spread, was analysed using a number of molecular approaches optimised specifically for this high temperature environment. 16S rDNA genes were amplified directly from sludge with universally conserved and Bacteria-specific rDNA gene primers and a clone library constructed that corresponded to the late thermophilic stage (t = 23 h) of the ATAD process. Sequence analyses revealed various 16S rDNA gene sequence types reflective of high bacterial community diversity. Members of the bacterial community included α- and β-Proteobacteria, Actinobacteria with High G + C content and Gram-Positive bacteria with a prevalence of the Firmicutes (Low G + C) division (class Clostridia and Bacillus). Most of the ATAD clones showed affiliation with bacterial species previously isolated or detected in other elevated temperature environments, at alkaline pH, or in cellulose rich environments. Several phylotypes associated with Fe(III)- and Mn(IV)-reducing anaerobes were also detected. The presence of anaerobes was of interest in such large scale systems where sub-optimal aeration and mixing is often the norm while the presence of large amounts of capnophiles suggest the possibility of limited convection and entrapment of CO(2) within the sludge matrix during digestion. Comparative analysis with organism identified in other ATAD systems revealed significant differences based on optimised techniques. The abundance of thermophilic, alkalophilic and cellulose-degrading phylotypes suggests that these organisms are responsible for maintaining the elevated temperature at the later stages of the ATAD process.
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Affiliation(s)
- Anna V Piterina
- Molecular Biochemistry Laboratory, Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland.
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