Biological treatment of wastewater with high concentrations of zinc and sulfate ions from zinc pyrithione synthesis

An enriched and domesticated bacteria consortium of sulfate-reducing bacteria(SRB)was used to treat wastewater from zinc pyrithione(ZPT)production,and the effects of different reaction parameters on sulfate reduction and zinc precipitation were evaluated.The single-factor experimental results showed that the removal rates of Zn2+and24SO?decreased with an increased ZPT concentration ranging from3.0to5.0mg/L.Zn2+and24SO?in wastewater were effectively removed under the conditions of30?35°C,pH7?8and an inoculum concentration of10%?25%.The presence of Fe0in the SRB system enhanced Zn2+and24SO?removal and may increase the resistance of SRB to the toxicity of Zn2+and ZPT in wastewater.A Box?Behnken design was used to evaluate the influence of the main operating parameters on the removal rate of24SO?.The optimum parameter values were found to be pH7.45,33.61°C and ZPT concentration of0.62mg/L,and the removal rate of24SO?reached a maximum of91.62%under these optimum conditions.

GA_3与EDTA强化黑麦草修复Pb污染土壤及其解毒机制

采用盆栽土培方法研究了生长调节剂GA3和重金属螯合剂EDTA强化黑麦草修复Pb外源浓度分别为250和500 mg·kg-1的污染土壤以及黑麦草Pb解毒机制.结果表明:细胞壁沉积和液泡区室化在黑麦草地上部分Pb的解毒中起重要作用.EDTA单独使用提高了植物体内Pb的浓度和Pb在细胞可溶组分和细胞器组分中的比例,增强了Pb对植物的毒害作用,从而使植物生物量显著下降(P<0.05).叶面喷洒低浓度GA3(1或10μmol·L-1)显著促进黑麦草对Pb的富集,但Pb在细胞器组分中的比例降低,缓解了Pb对植物细胞的伤害,从而促进了黑麦草的生长(P<0.05),其中1μmol·L-1GA3作用最显著.100μmol·L-1GA3降低了黑麦草体内Pb浓度,但Pb在细胞可溶组分和细胞器组分中的比例提高,使黑麦草的生物量明显低于对照.低浓度GA3可在一定程度上缓解Pb和/或EDTA对黑麦草的毒害,生物量表现为低浓度GA3单独>低浓度GA3+EDTA>EDTA单独使用.低浓度GA3和EDTA联用时的协同作用强化了黑麦草对Pb的富集,其中,在外源Pb浓度为500 mg·kg-1处理组中,EDTA+1μmol·L-1GA3使黑麦草地上部分Pb浓度和提取效率分别达到1250.6 mg·kg-1和1.1%.因此,1μmol·L-1GA3与EDTA联用在强化Pb污染土壤植物修复中具有很好的应用潜力.