Studies Of Treating Low-strength Organic Wastewater At Low Temperature Using ASBR-SBR System

The temperature of most of municipal sewage and lots of process wastewater is belowmesophilic range, and the strength is below 1000mgCOD/L. For the purpose ofreducing the cost of wastewater treatment and energy consumption, we must researchand develop anaerobic reactor that can treat the wastewater with low strength at lowtemperature.In the research on the treatment of organic wastewater with low strength at lowtemperature using ASBR—SBR, we focus on the specialties of quick startup andoperation of ASBR, and apply ASBR-SBR system to treat wastewater with lowstrength at low temperature. The aim is to exert the superiorities of ASBR and SBR,and to develop a new kind of treating method.The research indicates the quick startup of ASBR treating low strength wastewater atlow temperature is feasible.ASBR can treat the low strength wastewater at low temperature with proper efficiencyand low energy consumption. The effect of temperature above 13℃could be ignored,and most of municipal sewage and process wastewater can meet this requirement. Thebest hydraulic loading is 2m³/m³d. The intermittent agitation with machine results inhigher COD removal rate, but the intermittent time cannot be too long.The research indicates ASBR-SBR could treat the low strength wastewater at lowtemperature with high efficiency and low energy consumption. The total CODremoval rate is above 85%, and COD of effluent is below 50mg/L. By properoperation control, the system can get high NH₄⁺-N and PO₄^3--P removal rates of morethan 90%. The best operating condition for PO₄^3--P removal is to control DO between3-4mg/L during the 3-hours' reacting stage and drainage after 1-hour settling stage.The optimum concentration of MLSS in SBR is about 5000ml/L. ASBR can digestthe residual sludge from SBR, and the total yield of residual sludge is0.103kgMLSS/kgCOD.The research shows it is feasible for the quick startup and operation of ASBR treatinglow strength wastewater at low temperature, and ASBR-SBR system can treatwastewater at low temperature with high efficiency, low residual sludge and lowenergy consumption, which could solve the serious environment and energy shortageproblems facing to our country.