scholarly journals Looking for lipases and lipolytic organisms in low-temperature anaerobic reactors treating domestic wastewater

2021 ◽  
Author(s):  
Reihaneh Bashiri ◽  
Ben Allen ◽  
Burhan Shamurad ◽  
Martin Pabst ◽  
Thomas P Curtis ◽  
...  
Keyword(s):  
Low Temperature ◽  
Domestic Wastewater ◽  
Anaerobic Treatment ◽  
Bulk Liquid ◽  
Temperature Phase ◽  
Lipid Degradation ◽  
Outer Membranes ◽  
Anaerobic Reactors ◽  
Exogenous Lipid ◽  
Anaerobic Membrane Bioreactors

Poor lipid degradation limits low-temperature anaerobic treatment of domestic wastewater even when psychrophiles are used. We combined metagenomics and metaproteomics to find lipolytic bacteria and their potential, and actual, cold-adapted extracellular lipases in anaerobic membrane bioreactors treating domestic wastewater at 4℃ and 15℃. Of the 40 recovered putative lipolytic metagenome-assembled genomes (MAGs), only three (Chlorobium, Desulfobacter, and Mycolicibacterium) were common and abundant (relative abundance ≥ 1%) in all reactors. Notably, some MAGs that represented aerobic autotrophs contained lipases. Therefore, we hypothesised that the lipases we found are not always associated with exogenous lipid degradation and can have other roles such as polyhydroxyalkanoates (PHA) accumulation/degradation and interference with the outer membranes of other bacteria. Metaproteomics did not provide sufficient proteome coverage for relatively lower abundant proteins such as lipases though the expression of fadL genes, long-chain fatty acid transporters, was confirmed for four genera (Dechloromonas, Azoarcus, Aeromonas and Sulfurimonas), none of which were recovered as putative lipolytic MAGs. Metaproteomics also confirmed the presence of 15 relatively abundant (≥1%) genera in all reactors, of which at least 6 can potentially accumulate lipid/polyhydroxyalkanoates. For most putative lipolytic MAGs, there was no statistically significant correlation between the read abundance and reactor conditions such as temperature, phase (biofilm and bulk liquid), and feed type (treated by ultraviolet light or not). Results obtained by metagenomics and metaproteomics did not confirm each other and further work is required to identify the true lipid degraders in these systems. Keywords: Anaerobic treatment, domestic wastewater, psychrophilic extracellular lipases, metagenomics, metaproteomics

scholarly journals Low-temperature limitation of bioreactor sludge in anaerobic treatment of domestic wastewater

2013 ◽  
Vol 69 (5) ◽  
pp. 1004-1013 ◽  
Author(s):  
Emma J. Bowen ◽  
Jan Dolfing ◽  
Russell J. Davenport ◽  
Fiona L. Read ◽  
Thomas P. Curtis
Keyword(s):  
Low Temperature ◽  
Domestic Wastewater ◽  
Temperature Limit ◽  
Anaerobic Treatment ◽  
Anaerobic Sludge ◽  
Anaerobic Reactors ◽  
Theoretical Yield ◽  
Lower Temperature Limit ◽  
Temperature Limitation ◽  
Lower Temperature

Two strategies exist for seeding low-temperature anaerobic reactors: the use of specialist psychrophilic biomass or mesophilic bioreactor sludge acclimated to low temperature. We sought to determine the low-temperature limitation of anaerobic sludge from a bioreactor acclimated to UK temperatures (<15 °C). Anaerobic incubation tests using low-strength real domestic wastewater (DWW) and various alternative soluble COD sources were conducted at 4, 8 and 15 °C; methanogenesis and acidogenesis were monitored separately. Production of methane and acetate was observed; decreasing temperature resulted in decreased yields and increased ‘start-up’ times. At 4 °C methanogenesis not hydrolysis/acidogenesis was rate-limiting. The final methane yields at 4 °C were less than 35% of the theoretical potential whilst at 8 and 15 °C more than 75 and 100% of the theoretical yield was achieved respectively. We propose that the lower temperature limit for DWW treatment with anaerobic bioreactor sludge lies between 8 and 4 °C and that 8 °C is the threshold for reliable operation.

High rate domestic wastewater treatment at 15 °C using anaerobic reactors inoculated with cold-adapted sediments/soils – shaping robust methanogenic communities

2019 ◽  
Vol 5 (1) ◽  
pp. 70-82 ◽  
Author(s):  
Evangelos Petropoulos ◽  
Yongjie Yu ◽  
Shamas Tabraiz ◽  
Aminu Yakubu ◽  
Thomas P. Curtis ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Low Temperature ◽  
Domestic Wastewater ◽  
High Rate ◽  
Cold Adapted ◽  
Anaerobic Reactors ◽  
Domestic Wastewater Treatment

To choose the reactor format in which to employ a low temperature adapted seed for wastewater treatment, we compared a UASB and an AnMBRUASB (UF)reactor at low HRT and temperature (15 °C).

The Characteristic of the Soluble Microbial Products from an Anaerobic Reactor at Low Temperature

2012 ◽  
Vol 518-523 ◽  
pp. 1808-1812
Author(s):  
Lei Zhang ◽  
Wei Guang Li ◽  
Duo Ying Zhang ◽  
Ke Wang ◽  
Guang Zhi Wang
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
Membrane Separation ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Soluble Microbial Products ◽  
Anaerobic Reactors ◽  
Anaerobic Biodegradability ◽  
Microbial Products ◽  
Aerobic Biodegradability

A large amount of soluble chemical oxygen demand (COD) exists in the effluent from anaerobic treatment of wastewater at methophilic temperature, which consists of considerable portion of soluble microbial products (SMP). As the anaerobic treatment of wastewater was significantly influenced by temperature, it is great of importance to investigate the SMP from anaerobic reactors operated at low temperature in order to improve the performance. In this study, two lab-scale UASB reactors were performed to treat synthetic glucose and acetate wastewater respectively at an initial concentration of 1000 mg-COD/L at 15 °C. The SMP was found in the effluent from the glucose-fed UASB, and it was 6% of the influent COD concentration. The SMP did not accumulate in the acetate-fed UASB. The average aerobic biodegradability of the SMP was 90% and it was further enhanced by membrane separation of X100 (membrane with 100 k da molecular weight cut-offs). The anaerobic biodegradability of the SMP was 60%, and it was 100% for the fraction in which the molecular weight (MW) was lower than 10 k da. The fraction of low MW (lower than 10 k da) mainly consisted of 31.7% long chain alkanes and 13.6% esters. The aerobic polishing step is an available polishing step for the anaerobic treatment of wastewater at low temperature.

scholarly journals Lipolysis of domestic wastewater in anaerobic reactors operating at low temperatures

2018 ◽  
Vol 4 (7) ◽  
pp. 1002-1013 ◽  
Author(s):  
Evangelos Petropoulos ◽  
Jan Dolfing ◽  
Yongjie Yu ◽  
Matthew J. Wade ◽  
Emma J. Bowen ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Domestic Wastewater ◽  
Anaerobic Treatment ◽  
Major Barrier ◽  
Anaerobic Reactors

Poor breakdown of lipids is a major barrier to the anaerobic treatment of domestic wastewater at low temperatures.

Vacuum Operation for Overloaded Anaerobic Treatment Systems

1989 ◽  
Vol 21 (4-5) ◽  
pp. 87-95
Author(s):  
J. De Santis ◽  
A. A. Friedman
Keyword(s):  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Anaerobic Treatment ◽  
Optimum Operating ◽  
Operating Pressure ◽  
Simple Modification ◽  
Anaerobic Reactors ◽  
Fixed Film ◽  
Solids Retention ◽  
High Concentrations

Overloaded anaerobic treatment systems are characterized by high concentrations of volatile fatty acids and molecular hydrogen and poor conversion of primary substrates to methane. Previous experiments with fixed–film reactors indicated that operation with reduced headspace pressures enhanced anaerobic treatment. For these studies, four suspended culture, anaerobic reactors were operated with headspace pressures maintained between 0.5 and 1.0 atm and a solids retention time of 15 days. For lightly loaded systems (0.4 g SCOD/g VSS-day) vacuum operation provided minor treatment improvements. For shock organic loads, vacuum operation proved to be more stable and to support quicker recovery from upset conditions. Based on these studies and a companion set of bioassay tests, it was concluded that: (a) a loading rate of about 1.0 g SCOD/g VSS-day represents a practical loading limit for successful anaerobic treatment, (b) a headspace pressure of approximately 0.75 atm appears to be an optimum operating pressure for anaerobic systems and (c) simple modification to existing systems may provide relief for organically overloaded systems.

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