Preponderant psychrotrophs immobilized on PU foam to treat low temperature domestic wastewater

To guarantee the efficiency of biotreatment of domestic wastewater in chilly season, low temperature domestic wastewater was studied in laboratory by selecting out and immobilizing efficient preponderant psychrotrophs on polyurethane foams. The effect of internal circulation compound bioreactor (ICCBR) process which is a combination of activated sludge and biological contact oxidation, on treatment of low temperature domestic wastewater was analyzed and the factors affecting ICCBR process were investigated. Results show that ICCBR process can overcome the problem that effluent is always difficult to reach the discharge standard due to the low temperature in winter. The average removal rates of ICCBR process of COD, BOD₅ and TP are 86.66%, 90% and 89.67%, respectively. While hydraulic retention time (HRT) of the system is 10 h, dissolved oxygen concentrations of activated sludge process unit and biological contact oxidation unit are kept at 2.0-4.0 mg/L and 4.0-8.0 mg/L respectively; the sludge loading is kept at 0.25-0.30 kgCOD/(kgMLSS·d); the systemic effluent can achieve the first-degree B of pollutants discharge standard for municipal wastewater treatment plant in winter.