宝钢焦化废水处理脱氮研究与实践

Research and practice for total nitrogen removal in Baosteel coking wastewater treatment

针对上海提高新排放标准中总氮(TN)≤35 mg/L的要求,对焦化废水进行了脱氮研究。选取现场缺氧-好氧-好氧(A-O-O)工艺中前两段的A-O生化沉淀池1出水,在SBR内进行反硝化脱氮实验,考察葡萄糖、葡萄糖+乙酸钠、甲醇和甲醇+乙酸钠单一或复合碳源及投加反硝化菌种对脱氮的影响,确定最佳碳源为甲醇+乙酸钠,最佳反硝化水力停留时间为16 h。当反硝化菌液投加浓度为1 mg/L时,SBR出水TN满足达标排放要求。结合实验结果对宝钢焦化废水原有AO-O工艺改造升级为A-O-A-O二段脱氮工艺,并对生化出水实施进一步的物化混凝处理。改造后,工艺长期运行稳定,最终出水完全达到上海市污水综合排放标准(DB 31/199-2009)TN≤35 mg/L的要求,并满足氰化物、氟化物以及COD的排放要求。

Total nitrogen(TN) removal from coking wastewater was investigated aiming for the achievement of effluent TN≤35 mg/L target of the new discharge standard issued in Shanghai.The wastewater from the effluent of sedimentation tank after anoxic-oxic(A-O) treatment in its currently operating anoxic-oxic-oxic(A-O-O) process was used for further denitrification test in a SBR reactor,in which glucose,glucose + sodium acetate, methanol,or methanol + sodium acetate were added as an external carbon source for nitrogen removal.The experimental results showed that methanol + sodium acetate was the best external carbon and the optimum HRT was 16 hrs.With the extra addition of solution containing denitrifier(1.0 mg/L) the SBR effluent could satisfy the discharge standard for TN.Based on the above lab-scale tests the former A-O-O coking wastewater treatment process was modified to anoxic-oxic-anoxic-oxic(A-O-A-O) process with two-stage nitrogen removal,and the effluent was further treated through coagulation process.The full-scale plant was operated steadily after modification and its effluent reached the T-CN,F-,COD and the new TN discharge standard.