河道底泥重金属污染特征及治理措施研究

Study on Characteristics and Control Measures of Heavy Metal Pollution in River Sediment

为了提高河道底泥中重金属的去除效率,以某矿区附近河流中的河道底泥为研究对象,在分析了目标河道底泥中重金属污染特征的基础之上,开展了适合该河道底泥的化学淋洗处理技术研究,考察了淋洗剂类型、淋洗剂浓度、淋洗时间、淋洗液p H值以及淋洗次数对重金属去除效率的影响。结果表明:目标河道底泥中重金属Cr、Cu和Ni的污染风险较为严重,其他重金属的含量相对较少。当复配淋洗剂的配方为m(槐糖脂)∶m(MGDA)=1∶2、淋洗剂浓度为0.5 mol·L^(-1)、淋洗时间为60 min、淋洗液p H值为3、淋洗次数为2时,化学淋洗法对目标河道底泥中重金属Cr、Cu和Ni的去除效率分别能够达到88.4%、85.4%和90.5%,处理后的河道底泥中重金属Cr、Cu和Ni的质量分数可以分别降低至183.3、88.8、33.9 mg·kg^(-1),均能够满足国家标准GB15618—2018中的风险筛选值控制标准。

In order to improve the removal efficiency of heavy metals in river sediment,a study was conducted on the river sediment near a mining area.Based on the analysis of the heavy metal pollution characteristics in the target river sediment,a chemical leaching treatment technology suitable for the river sediment was carried out.The effects of the type of leaching agent,concentration of leaching agent,leaching time,pH value of leaching solution,and leaching frequency on the removal efficiency of heavy metals were investigated.The results indicated that the pollution risk of heavy metals Cr,Cu,and Ni in the sediment of the target river was relatively serious,while the content of other heavy metals was relatively low.When the formula of the composite washing agent was m(sophorolipid)∶m(MGDA)=1∶2,the concentration of the washing agent was 0.5 mol·L^(-1),the washing time was 60 min,the pH value of the washing solution was 3,and the washing frequency was 2,the removal efficiency of heavy metals Cr,Cu,and Ni in the target river sediment by the chemical washing method reached 88.4%,85.4%,and 90.5%,respectively.The mass fractions of heavy metals Cr,Cu,and Ni in the treated river sediment were reduced to 183.3 mg·kg^(-1),88.8 mg·kg^(-1) and 33.9 mg·kg^(-1) respectively,meeting the risk screening value control standards in the national standard GB15618—2018.