乙烯碱渣废水脱氮除碳生物处理技术

Biological treatment technology for nitrogen and carbon removal from alkali residue wastewater in ethylene cracking unit

针对乙烯碱渣废水高盐、高COD的特点,采用低氧生物反应器开展脱氮除碳研究。实验结果表明:在反应器好氧区DO为0.5~1.0 mg/L,缺氧区DO为0.2~0.4 mg/L,好氧区HRT为15.3 h,缺氧区HRT为9.2 h,沉降区HRT为6 h的条件下,当进水TDS小于16000 mg/L、COD为166~1520 mg/L、氨氮质量浓度为8.4~32.6 mg/L、TN为10.4~33.8 mg/L时,处理后出水平均COD去除率为87.6%,平均氨氮去除率为90.7%,平均TN去除率为86.3%;当进水TDS升高至18120 mg/L时,COD去除率不受影响,平均COD去除率为89.7%,随着运行时间的延长,硝化细菌逐渐受到抑制,20 d后,氨氮去除率由80.3%逐渐降低至57.5%,TN去除率由75.2%降低至51.4%;TDS对废水中石油类污染物的去除影响不大,运行期间,其去除率保持在90%以上。

According to the characteristics of high salinity and high COD of alkali residue wastewater in ethylene cracking unit,a low-oxygen bioreactor was used for nitrogen and carbon removal from the wastewater.The experimental results show that:Under the conditions of DO of aerobic zone and anoxic zone 0.5-1.0 mg/L and DO 0.2-0.4 mg/L respectively,HRT of aerobic zone,anoxic zone and settling zone 15.3 h,9.2 h and 6 h respectively,inlet TDS below 16000 mg/L,COD 166-1520 mg/L,ammonia nitrogen mass concentration 8.4-32.6 mg/L and TN 10.4-33.8 mg/L,the average removal rate of COD,ammonia nitrogen and TN is 87.6%,90.7%,and 86.3%,respectively;When the inlet TDS is increased to 18120 mg/L,COD removal rate is not affected with the average value of 89.7%,while after 20 days,due to the inhibition of nitrifying bacteria with the extension of operation time,the ammonia nitrogen removal rate is gradually decreased from 80.3%to 57.5%,the TN removal rate is also decreased from 75.2%to 51.4%;TDS has little effect on removal of petroleum pollutants from the wastewater,and the removal rate remains above 90%during operation.