针铁矿、磁铁矿和石膏对2,4-二氯苯酚厌氧降解的影响

2,4-二氯苯酚(2,4-dichlorophenol,2,4-DCP)常用于农药生产,在水体和土壤中广泛分布,具有难降解、高毒性的特点.通过模拟自然过程,在厌氧反应体系中投加铁氧化物和硫酸盐矿物,重点考察了不同矿物对2,4-DCP降解的影响.结果发现,厌氧体系中针铁矿、磁铁矿和石膏对2,4-DCP均没有明显的吸附作用;质量衡算结果表明所有反应体系中仅发生2,4-DCP向4-氯苯酚(4-chlorophenol,4-CP)的转化;与无外加碳源组相比,乙酸钠的加入使得2,4-DCP的还原脱氯反应速率增大一倍.分析表明针铁矿和磁铁矿加入可刺激脱氯功能菌的生长或活性,进而提高微生物的电子传递能力和2,4-DCP的降解速率;石膏加入强烈抑制脱氯功能菌的生长或活性,进而抑制2,4-DCP的降解.研究结果对认识难生化降解卤代酚在厌氧环境中的迁移转化及环境工程中此类物质的处理具有潜在意义.

Effects of Goethite, Magnetite and Gypsum on the Anaerobic Degradation of 2,4-Dichlorophenol

2,4-dichlorophenol(2,4-DCP), a highly toxic and refractory organic compound, was commonly used in pesticide production and thus widely distributed in water and soil. Goethite, magnetite and gypsum were added into the anaerobic system which simulated the natural anaerobic process to evaluate their effects on the anaerobic degradation of 2,4-DCP. It indicated that goethite, magnetite and gypsum had no appreciable adsorption ability toward 2,4-DCP under anaerobic condition. Mass balance analysis showed that only the transformation of 2,4-DCP to 4-chlorophenol(4-CP) occurred in all experimental groups. The addition of sodium acetate doubled the reductive dechlorination rate of 2,4-DCP in comparison with the groups without exogenous carbon source. The reductive dechlorination rate of 2,4-DCP was enhanced by the addition of goethite and magnetite, which was caused by the improved metabolic activity of dechlorination bacteria that played an important role in the anaerobic degradation of 2,4-DCP. Gypsum greatly inhibited or even stopped the degradation process of 2,4-DCP through restraining the growth and activity of dechlorination bacteria. This study will shed light on the migration and degradation of refractory chlorinated organic contaminants in anaerobic sedimentary environment, and the treatment of such matters in environmental technology.