Abstract: Chemical oxygen demand(COD), NH₃-N are routine water-quality indexes. Large amount of extremely toxic waste liquid has been generated from COD and NH₃-N monitoring. Waste was utilized to control waste on controlled mixing. Control point was chosen according to character of raw waste liquid and process requirement. COD monitoring waste liquid (Ag 478mg/L;Cr 207.5mg/L;Hg 411.6mg/L) reacted with NH₃-N monitoring waste liquid (Hg 464.7mg/L) on control point. Waste liquid volume ratio was 1.16 and 1.2. After solid-liquid separation, Hg content of filtrate had been reduced to 10.07mg/L, 10.12mg/L. Removal rate of Hg was 97.7%. Ag content of filtrate had been reduced to 0.07mg/L. Removal rate of Ag was 99.99%. The burden of subsequent procedure had been significantly reduced. Hg and Ag were enriched in the form of sludge. Ag content of filtrate was under 0.5mg/L when waste liquid ratio was from 0.3 to 1.25. Hg removal ratio achieved more than 96% when waste liquid ratio was from 1.11 to 1.25. When 1 liter COD monitoring waste liquid was treated, 0.86 liter NH₃-N monitoring waste liquid was reduced synchronously on this process. I^- and Cl^- from raw waste liquid were utilized as precipitants of heavy metal ions. The advantage of controlled mixing process compared with conventional process includes smaller dosage, lower overall operational cost, purer heavy metal sludge, and less sludge quantity. Performance and mechanism of controlled mixing process were deeply discussed.

Key words: laboratory waste liquid, controlled mixing, waste control by waste, COD monitoring, NH₃-N monitoring, water quality monitoring, mercury, silver

摘要： 监测COD、NH₃-N产生的废液量大、剧毒,因此对于控制混合工艺采用以废治废的思路。本文针对原液特性及工艺需求选择控制点,监测COD废液(总银478mg/L,总铬207.5mg/L,总汞411.6mg/L)与NH₃-N废液(总汞464.7mg/L)在控制点(废液体积比1.16、1.2)进行反应,固液分离后,滤液中汞含量降至10.07mg/L、10.12 mg/L,汞去除率为97.7%;银含量降至0.07mg/L,银去除率99.97%,大大减轻后续处理负担。汞和银被富集于污泥,废液体积比为0.3～1.25,固液分离后溶液Ag含量低于0.5mg/L;去除汞的较佳范围为:废液体积比1.11～1.25倍,汞去除率达到96%以上。控制混合法处理1L监测COD废液,同时还可减少约0.86L的监测NH₃-N废液,使废液本身含有的I^-、Cl^-等成为沉淀剂。相比常规工艺,该方法加药量大幅减少,运行费用低,重金属盐纯度较高,污泥量少。

关键词: 实验室废液, 控制混合, 以废治废, 测COD, 测NH₃-N, 水质监测, 汞, 银