污水厂污泥卤素含量及水解酸化对总溴的影响

运用高温燃烧与离子色谱联用技术,分析了8个污水处理厂污泥中的总氯和总溴含量,并研究水解酸化工艺对污泥中总溴的降解规律.结果表明,污水处理厂污泥中的总氯质量分数(0.63～3.60 mg.g-1)比总溴质量分数(0.04～0.20 mg.g-1)约高1个数量级;同时,总氯质量分数比文献报道的有机氯质量分数(0.08～6.90 mg.g-1)高约2～4个数量级.与pH为5.5相比,pH为10.0条件下的水解酸化过程对污泥的总溴有明显的降解效果,但并不能确定高温水解酸化是否能比低温水解酸化降解更多的总溴.pH为10.0的水解酸化工艺可以减少污泥处置(如土地利用、焚烧)中的总溴风险;但是,也可能增加该工艺产生的挥发性脂肪酸(VFA)用于补充生物除磷脱氮碳源时的风险.

Total Chlorides and Bromines in Sewage Sludge and Variation of Total Bromines in Hydrolysis and Acidification Processes

The combined method of automatic quick furnace and ion chromatography was applied to investigating total chlorides and bromines in sewage sludge from eight wastewater treatment plants as well as total bromines in the degraded samples collected from hydrolysis and acidification processes.The results show that the content of total chlorides (0.63~3.6 mg·g-1) in sewage sludge is about one order of magnitude higher than that of total bromines (0.04~0.20 mg·g-1).Meanwhile,the content of total chlorides in this study is 2~4 orders of magnitude higher than that of organic chlorides in literature (0.08~6.9 mg·g-1).As for the hydrolysis and acidification processes,total bromines of sludge flocs are significantly degraded at pH 10.0 when compared with pH 5.5.However,the superiority of thermophilic condition on the degradation of total bromines of sludge flocs is uncertain when compared with mesophilic condition.This study reveals for the first time that the hydrolysis and acidification processes at pH 10.0 could reduce the total bromines of sludge flocs and thereby reduce the risk of sludge disposal (i.e.,land application,incineration).However,the volatile fatty acids (VFA) produced in the fermentation process at pH 10.0 may increase the risk as the carbon sources of tertiary treatment in WWTP,owing to the total bromines transferring from the solid state to the liquid state.