Control filamentous bulking caused by chlorine-resistant Type 021N bacteria through adding a biocide CTAB.
Filamentous bulking sludge due to excessive growth of filamentous bacteria is a serious operational problem in activated sludge plants. The addition of chemicals is one of widespread ways to control filamentous bulking. In this study, filamentous bulking in a continuous activated sludge system was found to be mainly caused by Eikelboom Type 021N filamentous bacteria likely due to low substrate concentration gradients. These Type 021N bacteria were found to be resistant to chlorination, maintaining cell integrity at a dosage of up to 80 mg Cl/gSS. An alternative biocidal agent, cetyltrimethyl ammonium bromide (CTAB), exhibited a much stronger biocidal effect on these filaments, which significantly improved sludge settleability. Type 021N with filamentous index of 5 was selectively killed, but floc-formers recovery their activity after CTAB termination. The study implied that CTAB might have more penetration capacity to cell wall of chlorine-resistant Type 021N bacteria. We therefore suggest the penetration property of filament cell wall should be considered or tested before the selection of biocide type in practice.
Key Laboratory of Beijing for Water Quality Science and Water Environmental Recovery Engineering, Beijing University of Technology, Beijing 100124, China.
Jianhua
J
Guo
Yongzhen
Y
Peng
Zhongwei
Z
Wang
Zhiguo
Z
Yuan
Xiong
X
Yang
Shuying
S
Wang
D019149:Bioreactors / Q000382:microbiology; D002473:Cell Wall / Q000187:drug effects; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000494:pharmacology*; D002713:Chlorine / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000187:drug effects*; D020563:Gammaproteobacteria / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D017404:In Situ Hybridization, Fluorescence; D012722:Sewage / Q000382:microbiology*; D018508:Water Purification / Q000379:methods
D002593:Cetrimonium Compounds; D004202:Disinfectants; D012722:Sewage; D002713:Chlorine; D000077286:Cetrimonium