Biodegradability of oily wastewater using rotating biological contactor combined with an external membrane

Background: a novel implementation of a hybrid membrane bioreactor (hmbr) has been studied in this paper. itis utilized as combination of rotating biological contractor (rbc) and an external membrane, as a new biologicalsystem for oily wastewater treatment.methods: chemical oxygen demand (cod) and total petroleum hydrocarbon (tph) as factors of biodegradabilityhas been evaluated. they are both compared together for different hydraulic retention times (hrts) and petroleumpollution concentrations in rbc and hmbr. the ratio of tph to cod of molasses has been varied between 0.2 to0.8 at two hrts of 18 and 24 hours while the temperature, ph and dissolved oxygen were kept in the range of20-25°c, 6.5-7.5, and 2-3.5 mg/l, respectively.results: the best tph removal efficiency (99%) was observed in tph/cod = 0.6 and hrt = 24 hr in hmbr andremoval efficiency was decreased in the ratios above 0.6 in both bioreactors.conclusions: the experimental results showed that hmbr had higher treatment efficiency than rbc at all ratiosand hrts.