锌难溶物硝化抑制作用实证研究

Empirical Study on Nitrification Inhibited by Zinc Insoluble Substances

锌离子对活性污泥的硝化功能具有抑制作用,但污水厂进水中往往含有碱性物质,会导致锌以难溶物形态存在于悬浮物中。基于此,结合某污水厂具体运行情况,就锌难溶物对活性污泥硝化功能的抑制作用进行了定性和定量分析。首先针对该污水厂进水混合液和上清液分别进行硝化功能抑制性实验,确定抑制物主要存在于悬浮物中,并通过对比锌含量和硝化抑制程度,判断锌难溶物即是抑制硝化功能的主要物质。随后就锌难溶物对活性污泥硝化功能的抑制进行了定量分析,发现当进入系统的锌含量在5 mg/L以下时,抑制作用不明显;当进水锌含量在7.5 mg/L以上时,活性污泥的硝化功能受到显著抑制。同时,由于锌难溶物具有可沉淀的特征,易在活性污泥中积累,并可逐渐增强其硝化抑制作用。此外,锌对硝化功能的抑制作用不会随锌停止进入系统而在短期内消失。

Zinc ions can inhibit the nitrification of activated sludge,but the influent of wastewater treatment plants often contains alkaline substances,which lead to the existence of zinc in the form of insoluble substances in the influent suspended solids.The inhibition effect of zinc insoluble substances on nitrification of activated sludge was analyzed qualitatively and quantitatively based on the operation practice of a wastewater treatment plant.Firstly,the nitrification inhibition test in the mixed liquid and supernatant of the influent of the plant was carried out respectively,and the inhibition was determined to exist mainly in the influent suspended solids,and zinc insoluble substances were confirmed to be the main substances to inhibit nitrification by comparing the content of zinc and the degree of nitrification inhibition.Then,the inhibition of zinc insoluble substances on the nitrification of activated sludge was quantitatively analyzed,and it was concluded that the inhibition effect was not obvious when the zinc content in the system was less than 5 mg/L.However,the nitrification of activated sludge was significantly inhibited when the zinc content in the influent was above 7.5 mg/L.In addition,zinc insoluble substances were easy to accumulate in activated sludge and gradually enhanced their inhibition effect due to precipitation.The inhibition of zinc on nitrification did not disappear in a short period when zinc stopped entering the system.