摘要
污泥目前被认为是磷酸盐矿的二次资源,焚烧处理可实现污泥中磷资源的浓缩富集,但其中重金属毒性问题尚待解决.该文以污泥焚烧灰渣为研究对象,利用马弗炉进行煅烧实验,通过改变反应时间(从10 min到60 min)、温度(从900℃到1200℃)及CaCl2的添加量(以Cl计,从1.5%到8.0%)研究重金属(Pb、Zn和Cu)的去除率及在煅烧灰渣中的赋存形态.结果表明:Pb有较高的去除率,且其去除率均随温度、时间及Cl含量的升高而升高,在1200℃、Cl含量为5.0%的时候有最大值为82.4%;Zn的去除率受温度的影响较大,高温时Zn有较高的去除率,且在1100℃时有最大值为83.9%;Cu的去除率较低,而在温度为1100℃时有最大的去除率为68.2%.就煅烧灰渣中重金属的赋存形态而言,各种工况下Pb在煅烧灰渣中均以残渣态存在;Zn在煅烧灰渣中主要也是以残渣态存在;Cu在煅烧后还存在一定的酸溶态,在900℃、煅烧10min时煅烧灰渣中酸溶态可达29.2%.增加CaCl2的添加量可以促进重金属的去除,同时使煅烧底渣中的重金属更稳定.地累积指数(Igeo)评价结果显示,煅烧底渣中的这3种重金属的污染程度都降低了.
Sewage sludge is considered to be the biggest secondary resource of phosphate.Sludge incineration reduces mass of the sludge,leading to concentrated phosphorus in the ash.However,most toxic heavy metals are also concentrated in SSA.This paper focused on the possibility for heavy metal removal from SSA during calcination process.The calcination experiment was carried out by the muffle furnace,with varying treatment temperature,residence time and additive amount of CaCl2 of 900 ~ 1200 ℃,10 ~ 60 min,and 1.5% ~ 8.0%(specified as Cl),respectively.The removal rate of heavy metals and their chemical speciation in calcination residues were investigated.The result showed that:Pb can be removed well in all experiments;the removal rate of Pb increased with increasing temperature,residence time and additive amount of CaCl2;the highest removal rate of Pb was 82.4%when the temperature was 1200 ℃ and additive amount of Cl was 5%;temperature was the main influence factor for Zn with the highest removal rate of83.9% presented at 1100 ℃;the removal rate of Cu was lower than Pb and Zn,and its highest value was 68.2% at 1100 ℃.In terms of the chemical speciation of heavy metals in calcination residues,Pb existed as residual form in all experiments,while other speciation was not detected;Zn also mainly existed as residual form;acid-soluble form of Cu existed obviously in calcination residues,was accounting for 29.2% when the temperature was 900 ℃and residence time was 10 min.With the increasing additive amount of CaCl2,the removal rate and the stability of heavy metals increased.The evaluation result of the index of geo-accumulation showed that the pollution levels of heavy metals in calcination residues were reduced.
出处
《环境科学学报》
CAS
CSCD
北大核心
2014年第10期2552-2558,共7页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(No.51276119)
国家重点基础研究项目(No.2011CB201500)~~
关键词
污泥灰渣
煅烧
重金属
脱除规律
地累积指数评价
sewage sludge ash
calcination
heavy metals
removal
index of geo-accumulation
