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Flores-Ramírez A, Ortega-Cuenca J, Cuetero-Martínez Y, de Los Cobos D, Noyola A. Viability and removal assessment of Escherichia coli and Salmonella spp. by real-time PCR with propidium monoazide in the hygienization of sewage sludge using three anaerobic processes. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 161:254-262. [PMID: 36907017 DOI: 10.1016/j.wasman.2023.02.019] [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: 12/19/2022] [Revised: 01/31/2023] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
Sewage sludge should be stabilized for its beneficial use and pathogens, among other factors, should comply with environmental regulations. Three sludge stabilization process were compared to assess their suitability for producing Class A biosolids: MAD-AT (mesophilic (37 °C) anaerobic digestion (MAD) followed by an alkaline treatment (AT)); TAD (thermophilic (55 °C) anaerobic digester); and TP-TAD (mild thermal (80 °C, 1 h) pretreatment (TP) followed by a TAD). E. coli and Salmonella spp. were determined, differentiating three possible states: total cells (qPCR), viable cells using the propidium monoazide method (PMA-qPCR), and culturable cells (MPN). Culture techniques followed by the confirmative biochemical tests identified the presence of Salmonella spp. in PS and MAD samples, while the molecular methods (qPCR and PMA-qPCR) showed negative results in all samples. The TP + TAD arrangement reduced the concentration of total and viable E. coli cells in a greater extent than the TAD process. However, an increase of culturable E. coli was observed in the corresponding TAD step, indicating that the mild thermal pretreatment induced the viable but non-culturable state in E. coli. In addition, the PMA technique did not discriminate viable from non-viable bacteria in complex matrices. The three processes produced Class A biosolids (fecal coliforms < 1000 MPN/gTS and Salmonella spp, < 3 MPN/gTS) maintaining compliance after a 72 h storage period. It appears that the TP step favors the viable but not culturable state in E. coli cells, a finding that should be considered when adopting mild thermal treatment in sludge stabilization process arrangements.
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Affiliation(s)
- A Flores-Ramírez
- Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Circuito Escolar, Ciudad Universitaria, Coyoacán 04510, Ciudad de México, México
| | - J Ortega-Cuenca
- Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Circuito Escolar, Ciudad Universitaria, Coyoacán 04510, Ciudad de México, México
| | - Y Cuetero-Martínez
- Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Circuito Escolar, Ciudad Universitaria, Coyoacán 04510, Ciudad de México, México
| | - D de Los Cobos
- Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Circuito Escolar, Ciudad Universitaria, Coyoacán 04510, Ciudad de México, México
| | - A Noyola
- Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Circuito Escolar, Ciudad Universitaria, Coyoacán 04510, Ciudad de México, México.
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Tsigkou K, Zagklis D, Tsafrakidou P, Zafiri C, Kornaros M. Composting of anaerobic sludge from the co-digestion of used disposable nappies and expired food products. WASTE MANAGEMENT (NEW YORK, N.Y.) 2020; 118:655-666. [PMID: 33011543 DOI: 10.1016/j.wasman.2020.09.024] [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: 06/26/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Anaerobic sludge originating from the co-digestion of used disposable nappies and expired food products treated in a pilot two-stage system was examined as feed material for a continuous pilot-scale composter (capacity: 300 L feed per week). The feed materials and final compost products were analyzed and evaluated for their suitability as compost materials. Ιn terms of stability, the compost products were identified as stable through static respiratory index measurement (0.11-0.24 g O2/(kg Volatile Solids h)), heavy metals concentrations were within acceptable limits (i.e. concentration of Cu, Cd, Zn, Pb, Cr, As lower than 1 mg/kg dry mass) as well as polycyclic aromatic hydrocarbons (0.06-0.34 mg/kg dry mass lower than 6 mg/kg dry mass). During composting, significant losses of nitrogen from the digestate and the urea added for C/N correction were observed (51-75%), indicating that the adjustment of C/N ratio through the addition of chemicals is not efficient in composting processes with forced aeration and the pre-existing nitrogen in digestate was susceptible to air-stripping. The continuous composting process implemented proved capable of producing mature compost with a retention time of 14 d. The final products were within acceptable limits for all the parameters examined, except for the presence of pathogens (Salmonella and Enterococcus) which were not eliminated, even though the composter reached 56 °C for 3-4 days at the thermophilic stage. The characteristics of the anaerobic sludge samples examined indicate that direct land application of the anaerobic effluent should be considered as an option.
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Affiliation(s)
- Konstantina Tsigkou
- Lab. of Biochemical Engineering & Environmental Technology (LBEET), Dept. of Chemical Engineering, University of Patras, 1 Karatheodori Str, 26504 Patras, Greece
| | - Dimitris Zagklis
- Green Technologies Ltd., 5 Ellinos Stratiotou Str., 26223 Patras, Greece
| | | | - Constantina Zafiri
- Green Technologies Ltd., 5 Ellinos Stratiotou Str., 26223 Patras, Greece
| | - Michael Kornaros
- Lab. of Biochemical Engineering & Environmental Technology (LBEET), Dept. of Chemical Engineering, University of Patras, 1 Karatheodori Str, 26504 Patras, Greece.
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Increased (Antibiotic-Resistant) Pathogen Indicator Organism Removal during (Hyper-)Thermophilic Anaerobic Digestion of Concentrated Black Water for Safe Nutrient Recovery. SUSTAINABILITY 2020. [DOI: 10.3390/su12229336] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Source separated toilet water is a valuable resource for energy and fertilizers as it has a high concentration of organics and nutrients, which can be reused in agriculture. Recovery of nutrients such as nitrogen, phosphorous, and potassium (NPK) decreases the dependency on energy-intensive processes or processes that rely on depleting natural resources. In new sanitation systems, concentrated black water (BW) is obtained by source-separated collection of toilet water. BW-derived products are often associated with safety issues, amongst which pathogens and antibiotic-resistant pathogens. This study presents results showing that thermophilic (55–60 °C) and hyperthermophilic (70 °C) anaerobic treatments had higher (antibiotic-resistant) culturable pathogen indicators removal than mesophilic anaerobic treatment. Hyperthermophilic and thermophilic anaerobic treatment successfully removed Escherichia coli and extended-spectrum β-lactamases producing E. coli from source-separated vacuum collected BW at retention times of 6–11 days and reached significantly higher removal rates than mesophilic (35 °C) anaerobic treatment (p < 0.05). The difference between thermophilic and hyperthermophilic treatment was insignificant, which justifies operation at 55 °C rather than 70 °C. This study is the first to quantify (antibiotic-resistant) E. coli in concentrated BW (10–40 gCOD/L) and to show that both thermophilic and hyperthermophilic anaerobic treatment can adequately remove these pathogen indicators.
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De Vrieze J, De Mulder T, Matassa S, Zhou J, Angenent LT, Boon N, Verstraete W. Stochasticity in microbiology: managing unpredictability to reach the Sustainable Development Goals. Microb Biotechnol 2020; 13:829-843. [PMID: 32311222 PMCID: PMC7264747 DOI: 10.1111/1751-7915.13575] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/04/2020] [Accepted: 03/25/2020] [Indexed: 01/06/2023] Open
Abstract
Pure (single) cultures of microorganisms and mixed microbial communities (microbiomes) have been important for centuries in providing renewable energy, clean water and food products to human society and will continue to play a crucial role to pursue the Sustainable Development Goals. To use microorganisms effectively, microbial engineered processes require adequate control. Microbial communities are shaped by manageable deterministic processes, but also by stochastic processes, which can promote unforeseeable variations and adaptations. Here, we highlight the impact of stochasticity in single culture and microbiome engineering. First, we discuss the concepts and mechanisms of stochasticity in relation to microbial ecology of single cultures and microbiomes. Second, we discuss the consequences of stochasticity in relation to process performance and human health, which are reflected in key disadvantages and important opportunities. Third, we propose a suitable decision tool to deal with stochasticity in which monitoring of stochasticity and setting the boundaries of stochasticity by regulators are central aspects. Stochasticity may give rise to some risks, such as the presence of pathogens in microbiomes. We argue here that by taking the necessary precautions and through clever monitoring and interpretation, these risks can be mitigated.
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Affiliation(s)
- Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Gent, Belgium
| | | | - Silvio Matassa
- Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, 80125, Naples, Italy
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Largus T Angenent
- Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Gent, Belgium
| | - Willy Verstraete
- Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Gent, Belgium
- Avecom NV, Industrieweg 122P, Wondelgem, 9032, Belgium
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F. Santos A, P. Santos C, M. Matos A, Cardoso O, J. Quina M. Effect of Thermal Drying and Chemical Treatments with Wastes on Microbiological Contamination Indicators in Sewage Sludge. Microorganisms 2020; 8:microorganisms8030376. [PMID: 32155983 PMCID: PMC7142961 DOI: 10.3390/microorganisms8030376] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/03/2020] [Accepted: 03/05/2020] [Indexed: 11/16/2022] Open
Abstract
This work aims to evaluate the microbiological contamination of sewage sludge (SS) collected in urban wastewater treatment plants (WWTP) from Portugal. Two types of SS were considered: urban mixed (UM) and from anaerobic digestion (AD). The two types of samples were characterized in relation to the main physical and chemical parameters, as well as the microbiological contamination (Escherichia coli and Salmonella spp). Then, sanitation tests were conducted through thermal drying and chemical treatments. Towards a circular economy, industrial alkaline wastes (green liquor dregs - GLD, lime mud, coal fly ash, eggshell) were tested as alternatives to lime. Only six out of nineteen samples complied with the legal limits for both microorganisms. However, drying at 130 °C sanitized selected samples below the E. coli limit, regardless of the initial moisture or contamination. Additionally, CaO (obtained from eggshell) led to the complete elimination of E. coli at any dosage studied (0.05–0.15 g/g SSwet basis). GLD evidenced the ability to reduce E. coli contamination at room temperature, but not enough to comply with the legal limit. In general, this work highlights the need to sanitize the SS before its application to the soil, and the positive role of some wastes on this goal.
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Affiliation(s)
- Andreia F. Santos
- CIEPQPF-Centre of Chemical Processes Engineering and Forest Products, Department of Chemical Engineering, University of Coimbra, 3030-790 Coimbra, Portugal; (C.P.S.); (M.J.Q.)
- Correspondence:
| | - Cátia P. Santos
- CIEPQPF-Centre of Chemical Processes Engineering and Forest Products, Department of Chemical Engineering, University of Coimbra, 3030-790 Coimbra, Portugal; (C.P.S.); (M.J.Q.)
| | - Ana M. Matos
- CIEPQPF-Centre of Chemical Processes Engineering and Forest Products, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; (A.M.M.); (O.C.)
| | - Olga Cardoso
- CIEPQPF-Centre of Chemical Processes Engineering and Forest Products, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; (A.M.M.); (O.C.)
| | - Margarida J. Quina
- CIEPQPF-Centre of Chemical Processes Engineering and Forest Products, Department of Chemical Engineering, University of Coimbra, 3030-790 Coimbra, Portugal; (C.P.S.); (M.J.Q.)
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De Vrieze J, Colica G, Pintucci C, Sarli J, Pedizzi C, Willeghems G, Bral A, Varga S, Prat D, Peng L, Spiller M, Buysse J, Colsen J, Benito O, Carballa M, Vlaeminck SE. Resource recovery from pig manure via an integrated approach: A technical and economic assessment for full-scale applications. BIORESOURCE TECHNOLOGY 2019; 272:582-593. [PMID: 30352731 DOI: 10.1016/j.biortech.2018.10.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 06/08/2023]
Abstract
Intensive livestock farming cannot be uncoupled from the massive production of manure, requiring adequate management to avoid environmental damage. The high carbon, nitrogen and phosphorus content of pig manure enables targeted resource recovery. Here, fifteen integrated scenarios for recovery of water, nutrients and energy are compared in terms of technical feasibility and economic viability. The recovery of refined nutrients with a higher market value and quality, i.e., (NH4)2SO4 for N and struvite for P, coincided with higher net costs, compared to basic composting. The inclusion of anaerobic digestion promoted nutrient recovery efficiency, and enabled energy recovery through electricity production. Co-digestion of the manure with carbon-rich waste streams increased electricity production, but did not result in lower process costs. Overall, key drivers for the selection of the optimal manure treatment scenario will include the market demand for more refined (vs. separated or concentrated) products, and the need for renewable electricity production.
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Affiliation(s)
- Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | - Giovanni Colica
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | - Cristina Pintucci
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | - Jimena Sarli
- Ahidra, Agua y Energía S.L., Carretera de Polinyà a Sentmenat 159, 1°1ª, 08213 Polinyà, Barcelona, Spain
| | - Chiara Pedizzi
- Department of Chemical Engineering, School of Engineering, Universidade de Santiago de Compostela, Rúa Lope Gómez de Marzoa s/n, 15782 Santiago de Compostela, Spain
| | - Gwen Willeghems
- Department of Agricultural Economics, Ghent University, Coupure Links 653, B-9000 Gent, Belgium
| | - Andreas Bral
- Department of Agricultural Economics, Ghent University, Coupure Links 653, B-9000 Gent, Belgium
| | - Sam Varga
- Colsen BV, Kreekzoom 5, 4561 GX Hulst, the Netherlands
| | - Delphine Prat
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium
| | - Lai Peng
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium; Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, Faculty of Science, University of Antwerp, Antwerpen, Belgium
| | - Marc Spiller
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, Faculty of Science, University of Antwerp, Antwerpen, Belgium
| | - Jeroen Buysse
- Department of Agricultural Economics, Ghent University, Coupure Links 653, B-9000 Gent, Belgium
| | - Joop Colsen
- Colsen BV, Kreekzoom 5, 4561 GX Hulst, the Netherlands
| | - Oscar Benito
- Ahidra, Agua y Energía S.L., Carretera de Polinyà a Sentmenat 159, 1°1ª, 08213 Polinyà, Barcelona, Spain
| | - Marta Carballa
- Department of Chemical Engineering, School of Engineering, Universidade de Santiago de Compostela, Rúa Lope Gómez de Marzoa s/n, 15782 Santiago de Compostela, Spain
| | - Siegfried E Vlaeminck
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium; Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, Faculty of Science, University of Antwerp, Antwerpen, Belgium.
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De Vrieze J, Boon N, Verstraete W. Taking the technical microbiome into the next decade. Environ Microbiol 2018; 20:1991-2000. [PMID: 29745026 DOI: 10.1111/1462-2920.14269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/03/2018] [Indexed: 01/03/2023]
Abstract
The 'microbiome' has become a buzzword. Multiple new technologies allow to gather information about microbial communities as they evolve under stable and variable environmental conditions. The challenge of the next decade will be to develop strategies to compose and manage microbiomes. Here, key aspects are considered that will be of crucial importance for future microbial technological developments. First, the need to deal not only with genotypes but also particularly with phenotypes is addressed. Microbial technologies are often highly dependent on specific core organisms to obtain the desired process outcome. Hence, it is essential to combine omics data with phenotypic information to invoke and control specific phenotypes in the microbiome. Second, the development and application of synthetic microbiomes is evaluated. The central importance of the core species is a no-brainer, but the implementation of proper satellite species is an important route to explore. Overall, for the next decade, microbiome research should no longer almost exclusively focus on its capacity to degrade and dissipate but rather on its remarkable capability to capture disordered components and upgrade them into high-value microbial products. These products can become valuable commodities in the cyclic economy, as reflected in the case of 'reversed sanitation', which is introduced here.
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Affiliation(s)
- Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent 9000, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent 9000, Belgium
| | - Willy Verstraete
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent 9000, Belgium.,Avecom NV, Industrieweg 122P, Wondelgem 9032, Belgium
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Romanazzi V, Bonetta S, Fornasero S, De Ceglia M, Gilli G, Traversi D. Assessing Methanobrevibacter smithii and Clostridium difficile as not conventional faecal indicators in effluents of a wastewater treatment plant integrated with sludge anaerobic digestion. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2016; 184:170-177. [PMID: 27697372 DOI: 10.1016/j.jenvman.2016.09.081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 06/06/2023]
Abstract
Wastewater treatment plants (WWTP) are an important source of surface water contamination by enteric pathogens, affecting the role of environmental water as a microbial reservoir. We describe the release to the environment of certain anaerobes of human and environmental concern. The work was focused on emerging microbial targets. They are tracing, by RT-qPCR, on WWTP effluents, both liquid and solid, when an anaerobic digestion step is included. The focus is placed on Clostridium spp. with the specific quantification of Clostridium perfringens, as typical bioindicator, and Clostridium difficile, as emerging pathogen not only confined into nosocomial infection. Moreover methanogens were quantified for their involvement in the anaerobic digestion, and in particular on Methanobrevibacter smithii as major methanogenic component of the human gut microbiome and as not conventional faecal indicator. In the water samples, a reduction, statistically significant, in all microbial targets was observed (p < 0.01), 2 log for the total bacteria, 1.4 log for the Clostridium spp. and M. smithii, 1 log for total methanogens, C. perfringens and C. difficile. The AD process contribute to a significant change in microbial levels into the sludge for total bacteria and total methanogens (p < 0.01), both when the input sludge are primary and secondary, while for the presence of Clostridium spp. and C. difficile there was not a significant change. The produced data are innovative showing which is the diffusion of such anaerobic microorganisms throughout the WWTP and opening a discussion on the implementation of possible techniques for a more efficient microbial removal from effluents, particularly bio-solids, to reduce the potential release of pathogens into the environment.
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Affiliation(s)
- Valeria Romanazzi
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126 Torino, Italy.
| | - Silvia Bonetta
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126 Torino, Italy.
| | - Stefania Fornasero
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126 Torino, Italy.
| | - Margherita De Ceglia
- SMAT - Depuratore di Castiglione Torinese, Società Metropolitana Acque Torino S.p.A., Corso XI Febbraio 14, 10152 Torino, Italy.
| | - Giorgio Gilli
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126 Torino, Italy.
| | - Deborah Traversi
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126 Torino, Italy.
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De Vrieze J, Smet D, Klok J, Colsen J, Angenent LT, Vlaeminck SE. Thermophilic sludge digestion improves energy balance and nutrient recovery potential in full-scale municipal wastewater treatment plants. BIORESOURCE TECHNOLOGY 2016; 218:1237-1245. [PMID: 27423372 DOI: 10.1016/j.biortech.2016.06.119] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 06/24/2016] [Accepted: 06/28/2016] [Indexed: 06/06/2023]
Abstract
The conventional treatment of municipal wastewater by means of activated sludge is typically energy demanding. Here, the potential benefits of: (1) the optimization of mesophilic digestion; and (2) transitioning to thermophilic sludge digestion in three wastewater treatment plants (Tilburg-Noord, Land van Cuijk and Bath) in the Netherlands is evaluated, including a full-scale trial validation in Bath. In Tilburg-Noord, thermophilic sludge digestion covered the energy requirements of the plant (102%), whereas 111% of sludge operational treatment costs could be covered in Bath. Thermophilic sludge digestion also resulted in a strong increase in nutrient release. The potential for nutrient recovery was evaluated via: (1) stripping/absorption of ammonium; (2) autotrophic removal of ammonium via partial nitritation/anammox; and (3) struvite precipitation. This research shows that optimization of sludge digestion may lead to a strong increase in energy recovery, sludge treatment costs reduction, and the potential for advanced nutrient management in full-scale sewage treatment plants.
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Affiliation(s)
- Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000 Gent, Belgium
| | - Davey Smet
- Colsen BV, Kreekzoom 5, 4561 GX Hulst, The Netherlands
| | - Jacob Klok
- Colsen BV, Kreekzoom 5, 4561 GX Hulst, The Netherlands
| | - Joop Colsen
- Colsen BV, Kreekzoom 5, 4561 GX Hulst, The Netherlands
| | - Largus T Angenent
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, United States
| | - Siegfried E Vlaeminck
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000 Gent, Belgium; Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium.
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10
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Liu HT. Achilles heel of environmental risk from recycling of sludge to soil as amendment: A summary in recent ten years (2007-2016). WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 56:575-583. [PMID: 27287008 DOI: 10.1016/j.wasman.2016.05.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 05/24/2016] [Accepted: 05/29/2016] [Indexed: 06/06/2023]
Abstract
Recycling sludge as a soil amendment has both positive and negative effects because of its enrichment in both nutrients and contaminants. So far, the negative effect has to be extensively investigated that the severities of different types of contaminants also remain unclear. The environmental behavior and risk of organic contaminant and pharmaceuticals, heavy metal and salt as well as pathogenic microorganisms brought by sludge amendment are summarized and discussed here. Organic contaminants and pharmaceuticals are typically found at low concentrations in sludge, the risks from sludge-amended soil decrease over time owing to its biodegradability. On the other hand, application of sludge generally increases soil salinity, which may cause physiological damage to plants grown in sludge-amended soil. In some extent, this negative effect can be alleviated by means of dilution; however, greater attention should be paid to long term increasing possible risk of eutrophication. Heavy metal (particularly of mobile heavy metals, such as Cd) with high concentrations in sludge and soil receiving considerable sludge can cause its incremental abundance in soil and crop contamination, further posing risks to humans, but most cases showed that there remained not excessive in heavy metal caused by sludge amendment. It is worth noting that increasing soil organic matter content may reduce transfer of heavy metal from soil to crops, but not restrict its uptake by crops at all. Combined literature together, it is summarized that heavy metal becomes a relatively severe bottleneck in recycling of sludge as soil amendment due to its non-biodegradability and potential damage to health by adventuring contamination from agricultural products. Particular attention should therefore be paid to long term monitoring the change of heavy metals concentration in sludge amended soil.
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Affiliation(s)
- Hong-Tao Liu
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
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11
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Ho D, Jensen P, Batstone D. Effects of temperature and hydraulic retention time on acetotrophic pathways and performance in high-rate sludge digestion. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:6468-76. [PMID: 24797677 DOI: 10.1021/es500074j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
High-rate anaerobic digestion of organic solids requires rapid hydrolysis and enhanced methanogenic growth rates, which can be achieved through elevated temperature (>55 °C) at short hydraulic retention times (HRT). This study assesses the effect of temperatures between 55 °C and 65 °C and HRTs between 2 and 4 days on process performance, microbial community structure, microbial capability, and acetotrophic pathways in thermophilic anaerobic reactors. Increasing the temperature did not enhance volatile solids (VS) destruction above the base value of 37% achieved at 55 °C and 4 days HRT. Stable isotopic signatures (δ13C) revealed that elevated temperature promoted syntrophic acetate oxidation, which accounted for 60% of the methane formation at 55 °C, and increasing substantially to 100% at 65 °C. The acetate consumption capacity dropped with increasing temperature (from 0.69-0.81 gCOD gVS(-1) d(-1) at 55 °C to 0.21-0.35 gCOD gVS(-1) d(-1) at 65 °C), based on specific activity testing of reactor contents. Community analysis using 16S rRNA pyrosequencing revealed the dominance of Methanosarcina at 55-60 °C. However, a further increase to 65 °C resulted in loss of Methanosarcina, with an accumulation of organic acids and reduced methane production. Similar issues were observed when reducing the HRT to 2 days, indicating that temperature<60 °C and HRT>3 days are critical to operate these systems stably.
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Affiliation(s)
- Dang Ho
- Advanced Water Management Centre, The University of Queensland , St Lucia, Queensland 4072, Australia
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