DNF-O^3-BAC工艺深度处理石化废水的效能和机理

Efficacy and mechanism of advanced treatment of petrochemical wastewater by DNF-O^3-BAC combined process

针对石化废水难以达到地方新标准的问题,通过DNF-O^3-BAC工艺对石化废水进行深度处理,采用紫外分光光度法、重铬酸钾氧化法等方法对出水中各类氮浓度、COD、UV^254以及分子质量分布进行了检测;研究了不同碳源及C/N比对DNF单元反硝化性能的影响,并探究了DNF-O^3-BAC工艺深度处理石化废水的机理。结果表明:当水力停留时间为2 h,乙酸钠为最佳碳源,在C/N为4的条件下,NO^-3-N去除率达到96.7%,且几NO^-2-N积累;O^3的最佳投加量为20 mg·L^-1时,此时COD的去除率为45%左右,B/C稳定在0.2以上,UV^254去除率达到14%;在O^3投加量为20 mg·L^-1的条件下,最优接触时间为40 min,此时COD去除率达到42%,B/C稳定在0.28,UV^254的去除率达到34%左右;相比原水,分子质量≤1 kDa的有机物的比例从69%上升到86%。各单元最优条件下的DNF-O^3-BAC工艺出水中COD为25 mg·L^-1,UV^254稳定在0.11,TN为2 mg·L^-1。DNF-O^3-BAC工艺实现了石化废水中有机物和TN的降解,达到了地方标准。

In order to solve the problem that petrochemical wastewater is difficult to meet the new local standards,the DNF-O^3-BAC combined process was used to perform advanced treatment of it.Various nitrogen forms,COD,UV^254 and molecular weight distribution in effluent were tested by ultraviolet spectroscopy,K^2Cr^2O^7 oxidation method,etc.,respectively.The effects of different carbon sources and C/N on denitrification performance of DNF unit were studied,and the advanced treatment mechanism of petrochemical wastewater by DNF-O^3-BAC process was also explored.The results showed that the removal rate of NO^-3-N could reach 96.7%and almost no NO^-2-N accumulated at C/N of 4,HRT of 2 h and the most suitable carbon source of sodium acetate.At the best O^3 dosage of 20 mg·L^-1,the removal rate of COD was about 45%,the B/C ratio was stable above 0.2,and the removal rate of UV^254 reached 14%.At O3 dosage of 20 mg·L^-1,the optimal contact time was 40 min,and COD removal rate reached 42%,the B/C ratio was stable at 0.28,and UV^254 removal rate reached about 34%.Compared with influent water,the proportion of organic matter with molecular weight≤1 kDa increased from 69%to 86%.Under the optimal conditions of each unit,the COD in effluent of DNF-O^3-BAC process reached 25 mg·L^-1,UV^254 was stable at 0.11,and TN reached 2 mg·L^-1.DNF-O^3-BAC combined process could realize the degradation of organics and TN in petrochemical wastewater,and the effluent water quality met the local standards.