多段A/O工艺处理制革废水一级生化出水的效能

Efficiency of a multi-stage anoxic/oxic process treating tannery wastewater following a biochemical pretreatment

针对现有制革废水处理工艺难以使氨氮达标排放的问题,引入多段A/O工艺(MAOP)作为制革废水二级生物处理单元,探讨分段进水、水力停留时间(HRT)以及污泥回流比(R)对其COD和氨氮同步去除的影响.结果证明,无论是否分段进水,四段MAOP对制革废水一级生化出水均有良好的COD去除效果,当污泥停留时间(SRT)为18d、HRT不小于24h时,其出水浓度都可保持在300mg/L以下,满足GB8978-1996二级排放标准.在各段进水比为4:3:2:1、R 100%、HRT 48h、SRT 18d条件下,MAOP对制革废水一级生化出水的氨氮去除率高达97.7%,出水浓度3.6mg/L左右,达到GB8978-1996一级排放标准.MAOP同时具备反硝化、短程硝化反硝化、同步硝化反硝化等多种脱氮机制,是一种颇具前景的制革废水生物脱氮技术.

Ammonia nitrogen （NH4＋-N） removal is not satisfactory in the existing tannery wastewater treatment processes. In order to solve the problem, a multi-stage anoxic/oxic process （MAOP） was introduced as a secondary biological treatment unit to treat tannery wastewater deeply. The MAOP was a four-stage anoxic/oxic process and the influence of step-feeding, hydraulic retention time （HRT） and sludge return rate （R） on its simultaneous removal efficiency of chemical oxygen demand （COD） and NHa-N was investigated. The results showed that the MAOP was effective in COD removal. Whatever the step-feeding was carried out, the effluent COD was less than 300mg/L with HRT 24h and solid residence time （SRT） 18d, coming up to the secondary emission standards of GB8978-1996. With the same HRT and SRT, the NH4＋-N removal was up to 97.7% when the inflow distribution ratio and R were 4：3：2：land 100% respectively. The effluent NH4＋-N about 3.6mg/L met the primary emission standards of GB8978-1996. A multiple mechanism of denitrification, shortcut nitrification, simultaneous nitrification and denitrification could be occur in the MAOP. It was suggested that MAOP was a promising biological denitrification process for tannery wastewater treatment.