复杂水体中五日生化需氧量测定的硝化抑制

Inhibition to Nitrifi cstion in Determination of Biochemical Oxygen Demand After Five Days in Complex Water

利用丙烯基硫脲对有机污染物硝化过程进行抑制.五日生化需氧量反映的是有机污染物生物氧化过程中碳化阶段的耗氧量,而硝化阶段会导致测定结果显著偏高.未知水样基体复杂,很难判断是否存在会引起硝化作用的硝化细菌,往往导致测定结果偏高甚至出现生化需氧量大于化学需氧量（即B/C 值大于1）的不合理现象.向每升稀释水中加入0.1% 的丙烯基硫脲硝化抑制剂,对基体复杂样品进行稀释后测定,使得样品的B/C 值回到理论正常值（0.2～0.7）的范围内,对空白样品和标准样品的实验结果均满足国标方法的质控保证及要求.生化需氧量测定时间长而难以进行复测,该方法有效地排除了干扰,操作简便,降低了生化需氧量测定过程中稀释倍数选择不合适的风险,减小了工作量,提高了准确度.该方法对正常水样的测定结果不产生显著影响,适用于大批量复杂水体样品的测定.

Nitration reaction was inhibited by allyl thiourea. Biochemical oxygen demand after five days is oxygen amount consumed by the decomposition of organic pollutants in biochemistry process. Nitration reaction caused the estimated value significantly increased and even caused chemical oxygen demand more than biochemical oxygen demand. Through adding 0.1% allyl thiourea into dilution water, the method made B/C value of water sample come back to the normal value between 0.2 and 0.7. The results of the blank sample and the standard sample met the requirement of the national standard method. This method was effectively eliminating interference, simple operation, and reducing the risk of the test to select dilution ratio. It has no significant effects on water without interference, and also can simplify the determining procedure of large batches of compositional complicated water samples.