On-site treatment of higher-load graywater at different loading rates using submerged membrane bioreactor


Gokongwei College of Engineering


Chemical Engineering

Document Type

Conference Proceeding

Source Title

NOWRA 16th Annual Technical Education Conference & Exposition

Publication Date



The treatment of kitchen sink wastewater without energy requirement in permeate withdrawal was investigated using submerged membrane bioreactor (subMBR). The effect of organic loading rate (OLR) was determined by monitoring the organic matter removal, nitrogen and phosphorous, and permeate flux decline. Four lab-scale subMBR were operated at HRT of 4.5, 7, 12, and 24 hours giving a corresponding OLR of 6.9, 4.5, 2.6, and 1.3 kgCOD/m3-day, respectively. The wastewater was obtained from the university’s cafeteria with COD range of 770-2,050 mg/L. Regardless of the high variations of COD supplied, relatively stable permeates were obtained at OLR 4.5, 2.6, and 1.3 kgCOD/m3-day with COD < 40 mg/L. HRT of 4.5 hours was too short to degrade the high organic loading supplied to the system resulting to accumulation of organic matter inside the reactor and relatively high COD of permeate ranging from 40-70 mg/L. The accumulated organic matter in the high OLR system was due to the undecomposed matter from the influent, while the ones accumulated in low OLR system were due to the frequent sludge withdrawal and were high at low OLR since no sludge was withdrawn allowing their released during the decay of microorganisms in the sludge. Severe fouling was observed in the reactor of OLR of 6.9 kg/ m3-day, followed by 4.5, 2.6, and 1.3 kgCOD/m3-day, respectively. Furthermore, the treatment of a mixture of kitchen sink wastewater and washing machine wastewater gave a stable permeate at HRT ≥ 8 hours.



Chemical Engineering


Sewage—Purification; Membrane reactors

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