市政污水处理厂工艺运行探讨

INVESTIGATION ON THE RUNNING PERFORMANCE OF MUNICIPAL SEWAGE TREATMENT PLANT

目的在于探讨影响市政污水处理厂运行效果的工艺因素,提出可行的调控措施。通过对某市政污水处理厂2年的运行结果分析表明,有机物和悬浮物(SS)受水质和工艺等因素的影响较小,出水一般可以达标;NH3-N、TN去除效率偏低的原因除生物处理池水力停留时间(HRT)过短、有机负荷率偏高、好氧段曝气不均匀外,还与污泥消化上清液直接进入污水处理系统等有关;同样,TP和PO43--P的去除效率受污泥消化上清液和剩余污泥回流的影响也较大。研究认为,污水厂的二沉池富磷剩余污泥不宜直接回到初沉池浓缩处理,污泥消化和脱水上清液应除磷后再回到污水处理系统。

The objective of this study is to investigate the factors affecting running performances and the measures for improving the running effects of WWTPs.Through two-year running results of one wastewater treatment plant,it is showed that COD_ Cr ,BOD_5 and SS can always meet the discharge standard:the low removal efficiencies of NH_3-N and TN are concerned not only with short hydraulic retention time(HRT),high organic loading rates,and low DO in aerobic stages,but also with the supernatants of sludge anaerobic digestion recycling directly to inlet well of wastewater treatment facilities; the removing efficiencies of TP and PO~ 3- _4-P are influenced by the recycling of biological rich-phosphorus excess sludge and supernatants of sludge anaerobic digestion and dewatering too.The advantages and disadvantages of rich-phosphorus excess sludge recycling to primary sedimentation tanks are discussed; an additional treatment step is necessary for removing TP of supernatants from sludge anaerobic digestion before it flows back to wastewater treatment facilities.