煤液化高浓度污水处理厂中VOCs污染水平及其归趋

Occurrence and fate of VOCs in high concentration wastewater treatment plant of coal liquefaction

探讨了VOCs在煤液化高浓度污水处理过程中的去除规律、污染水平和分布行为,采用顶空-气相色谱/质谱法（HS/GC/MS）进行分析检测,结果表明,各工艺段出水中累计检出26种目标VOCs,且均以苯、乙苯、苯乙烯、甲苯、二甲苯（邻、间、对）等苯系物为主,ΣVOCs总浓度在339.28~562.36μg/L;4个产泥工艺段产出污泥中均以苯或苯乙烯含量为最高,ΣVOCs吸附量以及各VOCs单体的Kd值均以3T活性污泥段为最高;在吸附剂相对稳定时,污泥更倾向于吸附辛醇-水系数（Kow）大的VOCs污染物。污水处理过程中ΣVOCs的主要归趋途径为随水排出（60.33%）,其次为污泥吸附（22.95%）和挥发降解（16.72%）;随着lgKow的增大VOCs出水排放率逐渐降低,吸附去除率逐步增大,挥发降解去除率则出现先增后减的变化趋势,并在lgKow值为3.5左右时达到最大值。

This study presents the occurrance,adsorption characteristic and fate of volatile organic compounds（VOCs）in wastewater and sludges collected from high concentration wastewater treatment plant of coal liquefaction. Twenty-sixVOCs were detected cumulatively by headspace coupled with gas chromatography / mass spectrometry（HS / GC / MS） inthe effluent of each treatment unit. The most abundant compounds are BTEX of Benzene,Ethylbenzene,Styrene,Tolu-ene and（O/ M/ P）xylene etc. with total concentrations ranging from 266. 22 to 527. 45 μg / L,and the total VOCs atconcentrations from 339. 28 to 562. 36 μg / L;the highest concentration pollution in all sludges from four units of sludgegenerated is due to Benzene or Styrene,and both the maximal adsorption to ΣVOCs and the sludge-water partitioningcoefficients（Kd） of each VOC monomer are observed in 3T activated sludge. Under the relatively stable adsorbent,theadsorption would be stronger with the increase of octanol-water partition coefficient（ lgKow）. In the process ofwastewater treatment,wastewater-following discharge is the main fate pathway for the ΣVOCs（accounted for 60. 33%of the initial loadings）,followed by the sludge adsorption and volatilization / biodegradation（22. 95% and 16. 72% re-spectively）. With the increase of lgKow,the outflow discharge removal rate of VOC monomers decreased,but a gradu-ally increase of adsorption removal was found,and a peak in removal of VOCs through volatilization / biodegradation was observed around a lgKowvalue of 3. 5.