焦化污泥炭重金属风险及其处理焦化废水研究

Study on the risk of heavy metals in coking sludge carbon and its application in coking wastewater treatment

以焦化污泥制备焦化污泥炭,研究在炭化和硝酸改性过程中重金属形态变化和风险评价,并探索改性焦化污泥炭用于焦化废水处理的效能.焦化污泥(CWS)中Cr和Ni重金属含量远高于其他几种重金属,通过炭化得到焦化污泥炭(CWS-C),再活化后得到改性焦化污泥炭(CWS-N),生态风险因子(RI)从122.79(CWS)降低至33.70(CWS-N),说明CWS-N重金属污染风险很低.与CWS-C相比,CWS-N具有多种铁物相(FeO､Fe_(2)Al_(2)O_(4)､Fe_(3)O_(4)和Fe_(0.95)C_(0.005)),有利于Fe(II)/Fe(III)循环,能有效催化H_(2)O_(2)产生•OH,对焦化废水TOC的去除率高达66.3%.CWS-N上的活性组分铁的流失率低于0.5%,具有良好的催化稳定性.焦化废水中溶解性有机物主要为木质素类､脂质类和稠环化合物类,含N､S化合物占81.1%,经CWS-N催化降解后可去除大部分有机物.

Coking sludge carbon was prepared from coking sludge.Afterwards,the form transformation and risk assessment of heavy metals in the process of carbonization and modification with nitric acid were studied,and the efficiency of modified coking sludge carbon for coking wastewater treatment was explored.The contents of Cr and Ni in coking sludge(CWS)were much higher than other heavy metals.Coking sludge carbon(CWS-C)was obtained after carbonization and then the modified coking sludge carbon(CWS-C)was obtained after activation.The ecological risk factor(RI)was decreased from 122.79(CWS)to 33.70(CWS-N),indicating the low risk of heavy metal pollution in CWS-N.In comparison with CWS-C,CWS-N contained a variety of iron phases(i.e.,FeO,Fe_(2)Al_(2)O_(4),Fe_(3)O_(4)and Fe_(0.95)C_(0.005))which was in favor of the Fe(Ⅱ)/Fe(Ⅲ)cycle;thus,CWS-N could effectively catalyze H_(2)O_(2)to produce•OH,and the removal rate of TOC in coking wastewater was as high as 66.3%.The iron leaching rate of iron,the active component,on CWS-N was less than 0.5%,indicating its superior catalytic stability.The dissolved organic compounds in coking wastewater were mainly lignin,lipids and condensed nucleus compounds,while the compounds contained N or S accounted for 81.1%.Most organic compounds could be removed after catalytic degradation with CWS-N.