Fenton氧化剩余污泥过程重金属迁移及其形态变化

Heavy metal migration and speciation changes of residual sludge during the Fenton oxidation processing

采用Fenton氧化处理含重金属剩余污泥,通过BCR法测定并分析了污泥处理过程各重金属形态的变化,重点考察了pH、H_2O_2投加量、H_2O_2/Fe^(2+)比、温度(T)和反应时间(t)5个因素对重金属迁移及形态变化的影响。结果表明,利用Fenton氧化处理剩余污泥,污泥重金属形态变化显著,且受到初始pH、H_2O_2投加量、H_2O_2/Fe^(2+)比和温度的影响,但反应时间的影响较小。正交实验结果显示,Fenton氧化处理污泥的最佳条件为:初始pH1、H_2O_2投加量12 g·L^(-1)、H_2O_2/Fe^(2+)比10和温度50℃,此时污泥Cu、Mn和Zn 3种重金属的弱酸溶解态含量达到最高值,分别为72.66%、90.12%和87.51%。在最佳条件时,污泥上清液中Cu、Mn和Zn含量可分别从0.08、0.263和0.01 mg·L^(-1)增加到15.08、17.49、32.74 mg·L^(-1)。研究表明,Fenton氧化污泥过程提高了污泥中弱酸溶解态重金属含量,利于重金属从固相向液相转移,从而有效降低污泥饼中重金属含量,有利于污泥脱水后的进一步处理及其资源化。

Fenton oxidation was applied to treat residual sludge containing heavy metals,and the heavy metal migration and speciation changes were analyzed using the BCR method. The main objective of this work was to study the effects of initial pH,H2O2 dosage,H2O2/Fe2＋ratio,temperature,and reaction time on the migration and speciation of heavy metals with Fenton oxidation. The results showed that Fenton oxidation has an apparent effect on the migration and speciation of heavy metals,and the key influential factors were the initial pH,H2O2 dosage,H2O2/Fe2＋ratio,and temperature. However,the reaction time had no apparent effect on the migration and speciation of heavy metals. According to the orthogonal experiment results and the acid soluble fraction concentrations,the optimum reaction conditions were as follows： initial pH of 1,H2O2 dosage of 12 g·L-1,H2O2/Fe2＋ratio of10,and T of 50 ℃. Under these conditions,the acid soluble fractions of Cu,Zn,and Mn in the sludge were maximized at 72. 66%,90. 12%,and 87. 51%,respectively. The results showed that the acid soluble fraction of heavy metals in the sludge was increased by Fenton oxidation,and the transfer of heavy metals from the solid phase to the liquid phase was promoted. Under the optimum conditions,the concentration of Cu,Mn,and Zn in the sludge supernatant increased from 0. 08,0. 263,and 0. 01 mg·L-1to 15. 08,17. 49,and 32. 74 mg·L-1,respectively.This study indicated that the heavy metal content of the sludge cake was effectively decreased by the Fenton oxidation process,which makes the sludge suitable for further treatment and resource utilization after sludge dewatering.