title: Effects of hydraulic retention time and carbon to nitrogen ratio on micro-pollutant biodegradation in membrane bioreactor for leachate treatment.
abstract: This research investigated the biodegradation of the micro-pollutants in leachate by the membrane bioreactor (MBR) system under six treatment conditions, comprising two C/N ratios (6, 10) and three hydraulic retention time (HRT) durations (6, 12, 24h). The experimental results indicated that the C/N 6 environment was more advantageous to the bacterial growth. The bacterial communities residing in the sludge were those of heterotrophic bacteria (HB), heterotrophic nitrifying bacteria (HNB) and ammonia oxidizing bacteria (AOB). It was found that HB and HNB produced phenol hydroxylase (PH), esterase (EST), phthalate dioxygenase (PDO) and laccase (LAC) and also enhanced the biodegradation rate constants (k) in the system. At the same time, AOB promoted the production of HB and HNB. The findings also revealed that the 12h HRT was the optimal condition with regard to the highest growth of the bacteria responsible for the biodegradation of phenols and phthalates. Meanwhile, the longer HRT duration (i.e. 24h) was required to effectively bio-degrade carbamazepine (CBZ), N,N-diethyl-m-toluamide (DEET) and diclofenac (DCF).
authors.affiliation: Division of Biology, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi (RMUTT), Klong 6, Pathum Thani 12110, Thailand. Electronic address: jarungwit_b@rmutt.ac.th.
authors.forename: Jarungwit
authors.initials: J
authors.lastname: Boonnorat
authors.affiliation: Excellent Center of Waste Utilization and Management (ECoWaste), King Mongkut's University of Technology Thonburi (KMUTT), Bangkhuntien, Bangkok 10150, Thailand; National Center for Genetic Engineering and Biotechnology (BIOTEC), Bangkok 10150, Thailand.
authors.forename: Somkiet
authors.initials: S
authors.lastname: Techkarnjanaruk
authors.affiliation: Research Center for Sustainable Energy and Technology (RSET), Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Honda
authors.affiliation: Department of Civil Engineering, Faculty of Engineering, Srinakharinwirot University, Ongkharak, Nakhon Nayok 26120, Thailand.
authors.forename: Pradthana
authors.initials: P
authors.lastname: Prachanurak
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D002244:Carbon / Q000032:analysis*; D058645:Denaturing Gradient Gel Electrophoresis; D004591:Electrophoresis, Polyacrylamide Gel; D052836:Heterotrophic Processes; D007700:Kinetics; D008567:Membranes, Artificial; D058465:Nitrification; D009584:Nitrogen / Q000032:analysis*; D016133:Polymerase Chain Reaction; D060888:Real-Time Polymerase Chain Reaction; D012722:Sewage / Q000382:microbiology; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D008567:Membranes, Artificial; D012722:Sewage; D014874:Water Pollutants, Chemical; D002244:Carbon; D009584:Nitrogen
keywords: C/N ratio; Enzyme activity; Hydraulic retention time (HRT); Leachate; Membrane bioreactor (MBR); Micro-pollutants