Abstract: Black liquor produced from refined cotton production is highly concentrated refractory organic wastewater containing complicated components. Pretreatment by physical-chemical processes is preferred. The Acidification-Coagulation-Micro-electrolysis (ACM) was adopted to pretreat the black liquor. The effect of pH was investigated. UV-vis analysis and acute toxicity test were used for monitoring the changes of the composition. The results showed that the best pH value was 2 for acidification, 12 for coagulation and 4?5 for micro-electrolysis. COD decreased from 5400 to 1900 mg/L by the ratio of 65%. BOD5 decreased from 2860 to 1080 mg/L by the ratio of 62%. TOC decreased from 2080 to 906 mg/L by the ratio of 56%. Chromaticity decreased from 4500 to 50 by the ratio of 99%. Acute toxicity test showed that the dilution ratio of LIR50 (50% of luminosity inhibition rate) decreased from 250 to 17, meaning that the acute toxicity was reduced by 93%. Parts of refractory organic compounds containing conjugated double bonds and aromatic substances were precipitated or degraded. ACM for black liquor achieved good effect, providing favorable conditions for subsequent biological treatment.

Key words: physical-chemical processes, refined cotton, black liquor, acute toxicity

摘要： 采用酸析-混凝-微电解组合工艺预处理精制棉黑液, 研究pH对处理效果的影响。采用紫外-可见分光光度法和急性毒性试验研究组合工艺对精制棉黑液成分变化的影响。结果表明, 各阶段最佳pH条件为: 酸 析pH=2; 混凝pH=12; 微电解pH=4~5。通过组合工艺预处理, 精制棉黑液的COD由5400 mg/L降至1900 mg/L, 去除率为65%; BOD5由2860 mg/L降至1080 mg/L, 去除率为62%; TOC由2080 mg/L降至906 mg/L, 去除率为56%; 黑液色度由原水的4500降至50, 去除率为99%; 50%抑光率稀释比(LIR50)由250降至17, 急性毒性降低93%; 紫外可见吸收光谱结果显示, 部分含共轭双键和苯环的难生化降解物质得到析出或转化。酸析-混凝-微电解组合工艺预处理精制棉黑液取得了较好的处理效果, 为后续的生化处理提供了理论依据。

关键词: 物化工艺, 精制棉, 黑液, 急性毒性