Abstract:

Two parallel biological aerated filters (BAF), named as BAF1 and BAF2 (feeding with FeSO₄·7H₂O), were used to treat petrochemical secondary effluent. The performance of the reactors, especially the phosphorus removal ability, was investigated. In addition, the biomass and the biofilm activity were also studied. The results showed that the phosphorus removal could be enhanced obviously with the suitable dosage of FeSO₄·7H₂O (3—15 mg·L^-1). The phosphorus removal rate increased with the increase dosage of FeSO₄·7H₂O. However, the increasing trend became slowly when the dosage of FeSO₄·7H₂O was over 9 mg·L^-1. The TP removal rate was over 57.0% in BAF2 when the dosage of FeSO₄·7H₂O was 9 mg·L^-1, while it was only 7.1% in BAF1. The dosage of FeSO₄·7H₂O had no adverse effect on COD removal and the average COD removal rate in BAF2 was 5.4%,which was higher than that in BAF1. In addition, organic pollutants with high molecular weight were removed more obviously in BAF2 than that in BAF1. The dosage of FeSO₄·7H₂O had slightly effect on removal when the dosage was lower than 15 mg·L^-1. However, it decreased when the dosage was 15 mg·L^-1 due to the decrease of biofilm activity. There was almost no difference in TN removal in the two BAFs. The dosage of FeSO₄·7H₂O can decrease the amount of biofilm, but the biofilm reduction was not obvious when the dosage was lower than 12 mg·L^-1. The activity of the biofilm increased when the FeSO₄·7H₂O dosage was between 3 to 9 mg·L^-1, weakening the effect of the slightly biomass reduction, and therefore the performance of BAF2 was not affected.

Key words: biological aerated filter, petrochemical secondary effluent, enhanced phosphorus removal, biofilm, dehydrogenase activity

摘要：

为强化曝气生物滤池(BAF)的除磷效果,以石化二级出水为处理对象,研究了投加FeSO₄·7H₂O对BAF除磷性能的强化作用并对投量进行了优化,同时分析了FeSO₄·7H₂O投加对BAF除碳、脱氮和生物膜活性的影响。结果表明:投加少量FeSO₄·7H₂O(3~15 mg·L^-1)能有效强化BAF的除磷性能;BAF除磷的效果随FeSO₄·7H₂O投加量的增加而提高,但在投量高于9 mg·L^-1时增加趋势逐渐变缓,当FeSO₄·7H₂O的投加量为9 mg·L^-1时,TP的去除率达到57.0%以上,而同期平行运行的BAF除磷效率为7.1%。BAF中少量投加FeSO₄·7H₂O对COD的去除没有不良影响,COD的去除率比对比装置平均提高了5.4%左右,对相对分子质量较大的有机物去除明显。FeSO₄·7H₂O投加量低于12mg·L^-1时对 的去除没有不良影响,高于15 mg·L^-1时由于生物膜中微生物活性的下降 去除率有所降低。投加FeSO₄·7H₂O对TN的去除影响甚微。Fe²⁺的投加使得BAF中附着微生物的量有所降低,但在12 mg·L^-1以下时不会造成大的影响,FeSO₄·7H₂O投量在3~9 mg·L^-1时BAF中生物膜的脱氢酶活性和比好氧呼吸速率有所增加,可弥补生物量降低的影响,因此BAF的运行状况未受到影响。

关键词: 曝气生物滤池, 石化二级出水, 强化除磷, 生物膜, 脱氢酶活性