The standards,measurements and testing (SMT) program was employed to characterize the distribution of phosphorus (P) fractions in sewage sludge from three municipal wastewater treatment plants (WWTPs) in Beijing.Meanwhile,the release of phosphorus from sludge pretreated by thermal-alkaline combined method was investigated to provide theoretical support for pretreatment technology of phosphorus recovery from sewage sludge.The results showed that the inorganic phosphorus (IP) was the predominant fraction of total phosphorus (TP) in every plant,accounting for 63％,68％,75％,respectively.Bioavailable phosphorus had significant positive correlations with TP which accounted for 60％ to 76％ of TP.The results of thermal-alkaline pretreatment showed:1) For low-temperature thermolysis,both the transfer rate of total phosphorus from particle to supernatant and ratio of orthophosphate to TP in sludge supernatant all increased first and then decreased as the temperature increasing.The ratio of orthophosphate to TP in sludge supernatant was highest at 60 ℃,meanwhile the release rate of TP was also achieved a higher value.2) In the alkaline hydrolysis period,the ratio of orthophosphate to TP in sludge supernatant decreased while pH increased from 9 to 11 and remained stable when pH was higher than 11.However,the transfer rate of total phosphorus from particle to supernatant was positively correlated with pH.Considering the feasibility of sludge phosphorus recovery and the reagent costs,the best thermal-alkaline pretreatment conditions were pyrolysis temperature of 60 ℃ for 30 min and alkaline hydrolysis at pH =11 for 30 min.%以北京三家污水处理厂的污泥为研究对象,通过SMT法分析污泥中不同形态磷的含量与分布特征及热碱联合处理后污泥的释磷情况,为污泥磷回收预处理技术提供支持.结果表明:无机磷(IP)是污泥中磷的主要存在形态,三家污水处理厂污泥中IP分别占总磷(TP)的63％、68％、75％以上;生物有效磷在TP中均占60％ ～ 76％,并与总磷有显著的正相关关系.污泥的热碱联合处理结果表明:1)热解阶段:污泥上清液中正磷酸盐占总磷的比例和总磷释放率均随热解温度呈先上升后下降趋势;60℃时污泥上清液中正磷酸盐占TP的比例最高,TP释放率也较高.2)碱解阶段:pH为9～11时,污泥上清液中正磷酸盐占TP的比例随pH升高而减少,pH≥11后趋于稳定;TP释放率与pH大体呈正相关关系.考虑后期磷回收的可行性及药剂投加成本等原因,选择最适处理条件为:热解温度为60℃,热解时间为30 min;碱解pH为11,碱解时间为30 min.
展开▼
