Treating Low Strength Wastewater By Aerobic And Anaerobic Biologic Methods

The main content of this paper includes biological treatment of low strength wastewater under aerobic or anaerobic circumstance. A 4.27-liter upflow anaerobic sludge blanket(UASB) reactor is used to treat glucose wastewater, which COD concentration is about 500mg/l. Using activated sludge as inoculation, the UASB reactor starts-up at 35癈, with a organic load of only 0. 34gCOD/l. d. Approximately 90d late, Organic load of the UASB reactor increased to 0.34gCOD/l. d. Though the COD removal rates is not too high , granular sludge can be cultivated with diameter of 0. 5-2mm.At the same time, a 11. 5-1 iter MBBR (Moving Bed Biofi 1m Reactor) is tested for treatment of low strength synthetic wastewater. By microscopes and scanning electron microscopes, the microstructure of biomass in MBBR is observed. And the relationship between suspended sludge and biofilm on carrier elements is also presented. The MBBR, filed with 25% of carrier elements, is used to treat influent (100mg/l in COD concentration) for 1.9 hours HRT, which resulted in COD removal up to 85% and BOD., concentration of effluent less than 5mg/l.After the bench-scale experiment , two MBBR, which volume are both 120m, are established parallel to treat the low strength sewage for Fushun Ethene Corporation. The hydraulic retention time of the MBBR is 2.4h. After entering into a high efficiency fiber balls filtrate pot, the effluent can reach the standards for water recycling. Because of the low COD concentration of the influent, it is difficult for biomass to develop on carrier-elements in MBBR. By adding nutriment into the influent, the MBBR succeed to start-up in 3d.When using MBBR to treat the effluent of the UASB reactor, the biofilm on the carrier-elements can develop soon without inoculation.