Effects of sodium hypochlorite concentration on the methanogenic activity in an anaerobic fluidized membrane bioreactor

• Published in: The Science of the total environment 2019-08, Vol.678, p.85-93
• Main Authors: Lee, Eunseok, Rout, Prangya Ranjan, Shin, Chungheon, Bae, Jaeho
• Format: Article
• Language: English
• Subjects: Anaerobic fluidized membrane bioreactor; Anaerobiosis - drug effects; Bioreactors; Granular activated carbon; Methane - metabolism; NaOCl; Sodium Hypochlorite - toxicity; Specific acetoclastic methanogenic activity; Waste Disposal, Fluid - methods; Water Pollutants, Chemical - toxicity
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.04.396

The effect of membrane cleaning chemical, NaOCl on specific acetoclastic methanogenic activity (SAMA) of biomass in the anaerobic fluidized membrane bioreactors (AFMBRs) was assessed. Granular activated carbon (GAC) was used as a fluidizing media in the AFMBR to provide membrane scouring effect and surface for biofilm attachment. Effect of NaOCl on methane production was negligible for GAC with biofilm (bGAC) samples up to 150 mg NaOCl/g VSS, but was significant for the bulk liquid samples with noticeable lag period over 300 h even at the dosage of 50 mg NaOCl/g VSS. The toxicity of NaOCl on methane production was reduced in samples with virgin GAC (vGAC) by allowing 14 days of biomass buildup period prior to NaOCl addition, although the vGAC alone did not alleviate the toxicity. The results revealed that NaOCl concentrations beyond 100 mg/L within the reactor inhibited methanogenic activity and the effects were more pronounced on suspended biomass than the immobilized biomass on GAC. [Display omitted] •NaOCl's impact on methanogenic activity in anaerobic fluidized MBR was assessed.•Better toxicity tolerance of GAC with biofilm than bulk liquid biomass was noticed.•Methane production of GAC with biofilm was not affected up to 150 mg NaOCl/g VSS.•Within reactor, 100 mg/L of NaOCl was recommended for in-line AFMBR cleaning.