低强度超声波强化污水生物处理中超声辐照污泥比例的优化选择

通过超声波的SBR反应器与对照反应器处理人工配制生活污水的对比试验,研究了利用低强度超声波强化污水生物处理的另一个重要工艺参数———超声处理污泥比例(即超声处理污泥量占反应器内总污泥量的百分比).设置超声波反应器采用频率35kHz、声强0.3W/cm²超声波每隔8h取反应器中一定比例的活性污泥辐照10min后再返回反应器.结果表明,超声处理污泥比例为10%时,其COD和NH₃-N去除率可分别提高5%和0.5%左右,以好氧呼吸速率(Oxygen Uptake Rate,OUR)表示的污泥活性可提高12%以上.通过对污泥增长率的研究表明,当超声污泥比例为10%,超声波反应器内污泥的增长率比对照反应器降低了11%左右,减轻了后续污泥处理工序的负荷.随着超声处理污泥比例的增加,污泥体积指数SVI持续增大,但是超声污泥比例不超过10%对污泥沉降性能影响不大.因此,在超声强化污水生物处理工艺中,可采用强度0.3W/cm²超声波每隔8h取反应器中的10%的活性污泥辐照10min后再返回反应器,来提高反应器的生物处理效率.

Optimization of the Proportion of Irradiated Sludge for Enhancement of Sludge Activity in Biological Treatment of Wastewater by Low Intensity Ultrasound

The proportion of irradiated sludge(percentage that the irradiated sludge account for the total sludge in the reactor) for enhancement of biological treatment of wastewater by ultrasound(US) was optimized through contrast experiments between two sequenced batch reactors(SBR) with and without US.During the experiment,the US with intensity of 0.3W/cm² and frequency of 35kHz was employed to irradiate a certain percentage of sludge in the US-SBR reactor for 10 minutes every 8 h.The results showed that the removal rate of COD and NH₃-N could be increased of 5% and 0.5% respectively when the proportion of exposed sludge was 10%.A significant increase of sludge activity was also obtained with this proportion and more than 12% increase of OUR(Oxygen Uptake Rate,OUR) was achieved when 10% of sludge was irradiated.Moreover,the growth rate of activated sludge was decreased of 11% when the proportion of irradiated sludge was 10%,which can reduce the subsequent procedure of sludge treatment.With the increase of proportion of the irradiated sludge,SVI(sludge volume index) of the sludge in the US-SBR increased continuously,but it had little influence when the proportion of the irradiated sludge was no more than 10%.Therefore,to improve the treatment efficiency of biological reactor,US with intensity of 0.3W/cm² could be employed to irradiate 10% of the sludge in the biological reactor for 10 minutes every 8 h.