城市污水分段进水A/O脱氮工艺试验研究

对分段进水A/O脱氮工艺技术的经济性进行了分析:与单级A/O工艺相比,该工艺在运行中无需混合液内回流、反应器中平均污泥浓度高,具有脱氮效率高、基建投资和运行费用省等特点.并以西安市北石桥污水净化中心城市污水为处理对象,在有效容积为1.2 m3的四级分段进水A/O反应器中进行了试验研究.试验在各级进水流量分配比例依次为40%,30%,20%和10%,以及污泥回流比为50%的工况下,连续运转了70 d.结果表明:采用分段进水A/O脱氮工艺处理城市污水具有较强的耐冲击负荷能力,出水水质稳定.在水力停留时间为7.5 h,污泥龄为15 d时,其COD_Cr,NH₄++-N和TN的去除率分别为93%,95.8%和68.5%;反应器中的平均污泥浓度比单级A/O工艺提高约30%以上. 

A Pilot Study on Step-Feed BNR for Municipal Wastewater Treatment

The economy of step-feed biological nutrient removal(BNR) technology was discussed.Compared with the single stage A/O process,the step-feed BNR is efficient and cost-effective for nitrogen and phosphorous removal from municipal wastewater without mixed liquid suspended solid(MLSS) return.With the municipal wastewater at Beishiqiao Wastewater Treatment Center of Xi'an City as the treatment object,a four-stage pilot-scale step-feed BNR with useful volume of 1.2 m~3 was employed and operated with 50% of return activated sludge for more than 70 days.The feed split to each tank is 40%,30%,20% and 10% of total flow rate respectively.The results obtained showed that step-feed BNR is efficient for municipal wastewater treatment,having relatively strong bearing capability against impact load.The removal efficiencies of COD_(Cr),NH~ _4-N and TN could reach as high as 93%,95.8% and 68.5% respectively,under 7.5 hours of hydraulic retention time(HRT) and 15 days of sludge retention time(SRT).The averaged MLSS mass concentration in the reactor is about 30% higher than that of single stage A/O process.