硫代硫酸钠脱氯特性及其动力学分析

考察了二级生物处理出水经氯消毒后采用硫代硫酸钠脱氯的效果。结果表明，在氯消毒后初始余氯为10mgCl2／L的条件下，当反应时间为60min、硫代硫酸钠投量由理论投加量的100％增加至500％时，余氯去除率由41．2％增加到95．5％。硫代硫酸钠脱氯过程为分步反应：在最初的1min内，余氯脱除速率最快；反应1min后，自由氯脱除呈现零级反应，一氯胺、有机氯胺为一级反应；自由氯脱除速度快于一氯胺和有机氯胺，无机氯胺和有机氯胺是硫代硫酸钠脱氯反应速率的限制因素。当以硫代硫酸钠作为脱氯剂时，采用普通活性污泥法的污水处理厂需通过提高硫代硫酸钠投加量来实现快速脱氯，而采用生物脱氮工艺且硝化效果良好的污水处理厂只要保证足够的脱氯反应时间即可实现很好的脱氯效果。

Study on Dechlorination of Chlorinated Secondary Effluent with Sodium Thiosulfate

The dechlorination of disinfected secondary effluent with sodium thiosulfate was investigated. At initial residual chlorine of 10 mg Cl2/L in the disinfected secondary effluent, the removal of residual chlorine jumps from 41.2% to 95.5% after 60 min reaction with sodium thiosulfate, as the dosage increases from 100% to 500% of the theoretical value. The dechlorination reaction is found to be stepwise. During the initial 1 min of the reaction, there is a sharp drop in residual chlorine concentration. Thereafter, free chlorine shows a zero-order reduction rate, whereas the reduction of combined chorine follows first-order. Moreover, free chlorine shows a faster reduction rate than combined chlorine, indicating that combined chlorine is the limiting factor. When sodium thiosulfate is applied in the dechlorination, the dosage should be increased to speed up the reaction rate in a conventional activated sludge system, while with sufficient reaction time; it can ensure high chlorine removal in a biological nitrogen removal system.