Research On Treatment Efficiency Of Micro-aerobic Biological Reactor Enhanced By Modified Non-woven Carriers

A sewage biological treatment plant which was combined with the advantage s of micro-aerobic condition and biofilm process was developed in this study. It could be efficient remove pollutants with low consumption and reduce the sludge production when treating with low concentration, easily degradation wastewater. When treating with high concentration, refractory pollutants, it could be used as an effective pretreatment technology which was good at degrading pollutants and reducing the generation of harmful gas.Non-woven which has good spatial structure was selected as the main body of suspended carriers. In order to improve the hydrophilicity of non-woven, it was sequentially dealt with the modification processes(degreasing- coarsening- ion mulching). The new suspended carrier which was the combination of modified non-woven and silicone rubber pipe has good hydrophilicity and biofilm forming speed. Then, the modified non-woven carriers were used in the sequencing batch reactor. The sludge concentration and sludge form in the reactor were investigated under different dosing ratios of carriers. The results showed that the appropriate dosing ratios were between 10% and 15%.The treatment effect of the micro-aerobic biological reactor enhanced by modified non-woven carriers was investigated. The removal efficiencies of COD, NH4+-N and TN were 76.95%、65.02% and 58.61%, respectively. The removal efficiency of TP was not stable, and the average value was 47.85%.The influence of aeration rate on the micro-aerobic biological reactor was investigated. Compared to anaerobic environment, the micro-aerobic method could strengthen the mass transfer effect and improve the removal efficien cies of pollutants significantly. The DO concentration of micro-aerobic condition was maintained in relatively high level when the aeration rate was high. The microbial population structure was rich and the activity was stronger under this situation. Due to the above reasons, the micro-aerobic biological reactor has higher removal efficiency of pollutants. The influences of retention time and temperature on micro-aerobic biological reactor were also investigated. The results showed that the longer the retention time, the better the removal efficiency of pollutant. Increasing the temperature was helpful to improve the removal effect of the reactor, especially when the temperature was between 13 and 17 ℃.The micro-aerobic biological reactor was applied to treat sewage wastewater. The results showed that the removal efficiencies of COD、SS、ammonia and TN were 86.15%、93.69%、77.30% and 65.25%, respectively. To obtain the similar treatment effect, the amount of oxygen consumed by oxygen-consumption pollutants in the micro-aerobic biological reactor was 12.4 g/g, which was only 1/3 of the amount in aerobic biological reactor. The sludge yield was only 0.098 g MLSS/g COD, while the sludge yield was up to 0.36 g MLSS/g COD in aerobic biological reactorIt was also applied to treat pharmaceutical wastewater. The results showed that the biodegradability of wastewater was improved after treated by micro-aerobic biological reactor. The B/C ratio was increase from 0.31 to 0.39, and the VFA concentration was increased by about 85.5%. The sulfate reduction process and the generation of H2 S were inhibited in the micro-aerobic biological reactor.The removal mothed of nitrogen was multiple in the micro-aerobic biological reactor. The main approach for nitrogen removal was shortcut nitrification and denitrification.In order to explore the degradation mechanism of refractory, the degradation pathway, degradation rate and influence factors were investigated with nitrobenzene as a typical organic compound. The results showed that nitrobenzene could be removal completely when the concentration was 30 mg/L. The degradation method of nitrobenzene in reactor was: nitrobenzene�' aniline �'CO2+ H2O+ NH3. The aeration rate has great influence on the remval of aniline, the ramoval efficiency was reduced from 100% to 1.4% when aeration rate was reduced from 60 to 0 m L/(min·L). The load of the micro-aerobic biological reactor should not be higher than 0.09 kg NB/(m3·d) during. The coexistence substrates have a great influence on the degradation rate of nitrobenzene. The results showed that the degradation rate was faster and tolerance threshold of microorganism on nitrobenzene was higher when the coexistence substrates existed. The treatment effect of aniline by the micro-aerobic biological reactor was also examined. The results showed aniline could be removed effectively. The increase of aniline load had negative influence on the removal of COD and NH4+-N. Aniline could not be removal completely when the aniline load was above 0.12 kg AN/(m3·d).The combined process of pretreatment and artificial wetland was used in the treatment project of the black-odor river. The treatment effect of the micro-aerobic biological reactor as the pre-treatment process was investigated. Compared with the reactor under the anaerobic condition without carriers, the treatment effect was greatly improved in the reactor under micro-aerobic condition with carriers. The removal efficiencies of COD and NH4+-N was increased over one time. The cost of wastewater by the treatment project was only 0.08 ~ 0.12 yuan per ton.