PS缓释处理岩溶水石油污染过程中电子受体的利用

Availability of electron acceptors in the persulfate slow-release treatment of petroleum pollution in karst groundwater

原位化学氧化与生物修复技术在石油污染地下水中具有联合的潜力,但化学氧化对微生物活性具有抑制影响,通过缓释氧化剂技术可能会缓解这种影响。为了更好地认识基于过硫酸钠的缓释技术在修复岩溶地下水石油污染过程中对生物降解作用的影响,本研究利用微元体实验在微氧/厌氧条件下,开展了过硫酸盐缓释处理石油污染修复中不同电子受体利用的研究。实验设置了未投加缓释体和添加缓释体(过硫酸钠/石蜡质量比分别为0.5、1、2和3)的不同工况,通过未添加电子受体、添加100 mg·L^(-1)硝酸盐和添加100 mg·L^(-1)三价铁作为电子受体,探究石油污染物苯、甲苯、二甲苯(简称BTX)以及乙醇(EtOH)处理及电子受体的可利用性。结果表明:BTX的降解速率与缓释体过硫酸钠/石蜡质量比呈正相关,在过硫酸钠/石蜡质量比为2和3时降解速率较高,比乙醇更容易被化学氧化;BTX降解以化学氧化为主,而乙醇的降解则以微生物作用为主。过硫酸盐缓释条件下,生物作用中硝酸盐还原作用较为明显,硫酸盐还原作用较为微弱,铁还原作用不明显;硝酸盐最容易被利用为电子受体,其次为硫酸盐,三价铁被微生物利用的可能性最小。缓释体质量比不同、电子受体类型不同可导致优势菌属存在明显的差异,鞘氨醇单胞菌属和罗尔斯通氏菌属相对丰度普遍较高,二者均可利用多种电子受体降解污染物,在生物降解上起到主要作用。

In situ chemical oxidation(ISCO)has the potential to combine with bioremediation techniques in the remediation of petroleum-contaminated groundwater,but it can decrease the activity of microorganisms,which may be buffered by slow-release material(SRM)techniques.To better understand the effect of SRM with persulfate(PS)on the biodegradation in the remediation of petroleum pollution in karst groundwater,a microcosm experiment under microaerobic and anaerobic conditions was conducted to explore the availability of different electron acceptors.In the test,different working conditions without or with slow release PS(persulfate/paraffin mass ratios of 0.5,1,2,and 3)were set as follows:no addition of electron acceptor,addition of 100 mg·L^(−1) nitrate as electron acceptor,addition of 100 mg·L^(−1) Fe 3+as electron acceptor,the treatment of benzene,toluene,xylene(referred to as BTX)and ethanol(EtOH)was investigated,as well as the availability of electron acceptors.The results showed that the degradation rate of BTX was positively correlated with the mass ratio of SRMs,and the highest degradation rate constants occurred at persulfate/paraffin mass ratios of 2 and 3.BTX was more preferentially oxidized by PS than EtOH.BTX degradation was dominated by chemical oxidation,while EtOH dgradation was dominated by microbial action.With the presence of SRMs,nitrate reduction was more significant in microbial action,while sulfate reduction was relatively weak,iron reduction was unconspicuous.Nitrate was more readily used as an electron acceptor by microorganisms,followed by sulfate.However,the possibility of ferric iron used by microbial was slight.Different mass ratios of SRMs and different types of electron acceptors could lead to significant differences in the dominant genera.Both Sphingomonas spp.and Ralstonia spp.had higher relative abundances than others and played a major role in utilizing various electron acceptors to degrade pollutants.