市政污泥热解过程中重金属迁移特性及环境效应评估  

Migration and Environmental Effects of Heavy Metals in the Pyrolysis of Municipal Sludge

作　　者：姜媛媛 王彦 段文焱 左宁 陈芳媛[1] JIANG Yuan-yuan;WANG Yan;DUAN Wen-yan;ZUO Ning;CHEN Fang-yuan(Faculty of Environmental Science and Engineering,Kunming University of Science and Technology,Kunming 650604,China)

机构地区：[1]昆明理工大学环境科学与工程学院,昆明650604

出　　处：《环境科学》2021年第6期2966-2974,共9页Environmental Science

基　　金：国家自然科学基金项目(41763016);昆明理工大学分析测试基金项目(2019M20182207066)。

摘　　要：以昆明某市政污泥为原料,研究生物炭制备过程中重金属Fe、Zn、Mn和Ni的迁移特性,并基于其潜在环境风险确定污泥基生物炭制备的最佳热解温度.本实验选择总量较高的4种重金属Fe、Zn、Mn和Ni,采用BCR提取法测定不同热解温度下4种重金属的形态和含量变化,得到各金属的形态分布变化规律和迁移路径,利用潜在生态风险指数(PERI)和风险评估代码(RAC)对污泥基生物炭进行环境风险评估.结果表明,4种金属的易挥发程度排序为Zn>Mn>Fe>Ni,4种金属形态分布情况和变化规律各不相同,但迁移路径具有共通性.在低温热解阶段,不稳定形态向稳定形态转化;随着温度的升高,可氧化态和残渣态逐步分解破碎,部分逸散到大气中,部分形成可还原态.在环境风险评估方面,高温条件(>500℃)下制备的生物炭环境风险较低,500℃制备的生物炭经济性最好.Migration characteristics of the heavy metals Fe,Zn,Mn,and Ni during the preparation of biochar from municipal sludge were studied,and the optimal pyrolysis temperature for the preparation of biochar was determined based on potential environmental risks.Four heavy metals(Fe,Zn,Mn,and Ni)with high total contents in the biochar were selected to determine their species and content changes under different pyrolysis temperatures using the BCR extraction method.An environmental risk assessment for sludgebased biochar was also carried out using the potential ecological risk index(PERI)and risk assessment code(RAC).The results showed that the volatility of the four metals is ranked as follows:Zn>Mn>Fe>Ni.The distribution and transformation of the four metal species were different,but their migration paths shared similar characteristics.In the pyrolysis stage at low temperatures(<500℃),unstable fractions gradually changed into more stable species;under high temperatures(>500℃),some of the oxidizable and residual fractions were broken,which transformed into reducible fractions,and other fractions escaped into the atmosphere.In the environmental risk assessment,biochar prepared under high pyrolysis temperatures(>500℃)showed lower environmental risks,with the best outcomes at 500℃.

关 键 词：污泥基生物炭 重金属 环境效应 潜在风险指数 风险评估代码(RAC) 

分 类 号：X705[环境科学与工程—环境工程]