title: Performance and microbial community analysis in a modified anaerobic inclining-baffled reactor treating recycled paper mill effluent.
abstract: Recycled paper mill effluent (RPME) contains high levels of organic and solid compounds, causing operational problems for anaerobic biological treatment. In this study, a unique modified anaerobic inclining-baffled reactor (MAI-BR) has been developed to treat RPME at various initial chemical oxygen demand (COD) concentrations (1000-4000 mg/L) and hydraulic retention times (HRTs) (3 and 1 day). The COD removal efficiency was decreased from 96 to 83% when the organic loading rate (OLR) was increased from 0.33 to 4 g/L day. Throughout the study, a maximum methane yield of 0.25 L CH4/g COD was obtained, while the pH fluctuated in the range of 5.8 to 7.8. The reactor performance was influenced by the development and distribution of the microbial communities. Based on the next-generation sequencing (NGS) analysis, the microbial community represented a variety of bacterial phyla with significant homology to Euryarchaeota (43.06%), Planctomycetes (24.68%), Proteobacteria (21.58%), Acidobacteria (4.12%), Chloroflexi (3.14%), Firmicutes (1.12%), Bacteroidetes (1.02%), and others (1.28%). The NGS analysis showed that the microbial community was dominated by Methanosaeta concilii and Candidatus Kuenenia stuttgartiensis. This can be supported by the presence of filamentous and spherical microbes of different sizes. Additionally, methanogenic and anaerobic ammonium oxidation (ANAMMOX) microorganisms coexisted in all compartments, and these contributed to the overall degradation of substances in the RPME. Graphical abstract ᅟ.
authors.affiliation: College of Water Resources Engineering, Al-Qasim Green University, Babylon, Al Qasim Province, Iraq.
authors.forename: Haider M
authors.initials: HM
authors.lastname: Zwain
authors.affiliation: School of Civil Engineering, Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300, Nibong Tebal, Penang, Malaysia.|Solid Waste Management Cluster, Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300, Nibong Tebal, Penang, Malaysia.
authors.forename: Hamidi Abdul
authors.initials: HA
authors.lastname: Aziz
authors.affiliation: School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.|Nanyang Environment and Water Research Institute, Nanyang Technological University, CleanTech 1, Singapore, 637141, Singapore.
authors.forename: Wun Jern
authors.initials: WJ
authors.lastname: Ng
authors.affiliation: Solid Waste Management Cluster, Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300, Nibong Tebal, Penang, Malaysia. chirvan@usm.my.|School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300 Nibong Tebal, Penang, Malaysia. chirvan@usm.my.
authors.forename: Irvan
authors.initials: I
authors.lastname: Dahlan
mesh_terms: D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology*; D008697:Methane / Q000737:chemistry; D010209:Paper; D059027:Recycling; D014865:Waste Disposal, Fluid
chemical_list: D008697:Methane
keywords: Anaerobic degradation; Candidatus kuenenia stuttgartiensis; Methanosaeta concilii; Microbial community; Modified anaerobic inclining-baffled reactor; Morphology