title: Enhancement of microbial density and methane production in advanced anaerobic digestion of secondary sewage sludge by continuous removal of ammonia.
abstract: Ammonia inhibition mitigation in anaerobic digestion of high solids content of thermally hydrolysed secondary sewage sludge by the NH4+affinitive clinoptilolite and a strong acid type ion-exchange resin S957 was investigated. Continuous NH4+-N removal was achieved through ion-exchanging at both temperatures with average removals of 50 and 70% for the clinoptilolite and resin dosed reactors, respectively. Approximate 0.2-0.5unit of pH reduction was also observed in the dosed reactors. The synergy of NH4+-N removal and pH reduction exponentially decreased free NH3concentration, from 600 to 90mg/L at 43°C, which mitigated ammonia inhibition and improved methane yields by approximately 54%. Microbial community profiling suggested that facilitated by ammonia removal, the improvement in methane production was mainly achieved through the doubling in bacterial density and a 6-fold increase in population of the Methanosarcinaceae family, which in turn improved the degradation of residual volatile fatty acids, proteins and carbohydrates.
authors.affiliation: Wales Centre of Excellence for Anaerobic Digestion, Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK.
authors.forename: Bing
authors.initials: B
authors.lastname: Tao
authors.affiliation: Wales Centre of Excellence for Anaerobic Digestion, Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK.
authors.forename: Joanne
authors.initials: J
authors.lastname: Donnelly
authors.affiliation: Wales Centre of Excellence for Anaerobic Digestion, Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK.
authors.forename: Ivo
authors.initials: I
authors.lastname: Oliveira
authors.affiliation: Wales Centre of Excellence for Anaerobic Digestion, Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK; Welsh Water, Nelson, Treharris CF46 6LY, UK.
authors.forename: Ruth
authors.initials: R
authors.lastname: Anthony
authors.affiliation: Welsh Water, Nelson, Treharris CF46 6LY, UK.
authors.forename: Victoria
authors.initials: V
authors.lastname: Wilson
authors.affiliation: Wales Centre of Excellence for Anaerobic Digestion, Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK. Electronic address: sandra.esteves@southwales.ac.uk.
authors.forename: Sandra R
authors.initials: SR
authors.lastname: Esteves
mesh_terms: D019342:Acetic Acid / Q000032:analysis; D000641:Ammonia / Q000302:isolation & purification*; D064751:Ammonium Compounds / Q000302:isolation & purification; D000693:Anaerobiosis; D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D002241:Carbohydrates / Q000032:analysis; D005232:Fatty Acids, Volatile / Q000032:analysis; D018628:Gene Dosage; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D008697:Methane / Q000096:biosynthesis* / Q000378:metabolism; D011422:Propionates / Q000032:analysis; D012117:Resins, Synthetic / Q000737:chemistry; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D017641:Zeolites / Q000737:chemistry
chemical_list: D064751:Ammonium Compounds; D002241:Carbohydrates; D005232:Fatty Acids, Volatile; D011422:Propionates; D012117:Resins, Synthetic; D012722:Sewage; D017641:Zeolites; D000641:Ammonia; C029658:propionic acid; D008697:Methane; D019342:Acetic Acid
keywords: Advanced anaerobic digestion; Ammonia inhibition; Bacteria and methanogens gene abundance; Ion-exchange resin; Thermal hydrolysed secondary sewage sludge; Zeolite