Ultrafiltration membrane bioreactor for urban wastewater reclamation

A 162-day pilot-scale operation for reclamation of urban wastewater was stu died by using an ultrafiltration membrane bioreactor (UMBR). Performance of the UMBR was investigated with a sludge retention time (SRT) of 5, 15, and 30 days, a hydraulic retention time (HRT) of 5 h, and membrane flux betwee n 75 and 1501 m(-2) h(-1), respectively. It was observed that the highest s ludge concentration in the reactor viz. a suspended solids (SS's) concentra tion of 23.1 g l(-1) and a volatile suspended solids (VSS's) concentration of 13.5 g l(-1), respectively, could be reached. The ratio of sludge VSS to sludge chemical oxygen demand (COD) was 1.428 in the study, which approxim ated to the theoretical value of 1.415. Mass loading rates of the UMBR were close to those of conventional activated sludge processes (CASP's), while the volumetric loading rates were two to five times those of GASP. Averaged 97% of GOD, 96.2% of ammonia nitrogen (NH3-N), and 100% of SS's were remov ed. It was found that the bioreactor was responsible for 85% of COD removal , while 12% was due to separation of the membrane module. The reclaimed wat er could be reused directly for municipal purposes or indirectly for indust rial uses after additional treatment. (C) 2000 Elsevier Science B.V. All ri ghts reserved.