Research On Pollution And Remediation Of Heavy Metal Contaminated Sediments In Suzhou River

Water sediment (sediment) is an important part of the rivers,lakes and other natural water ecosystems,and it's also a significant integral link of material cycle in water ecosystem. Different states of heavy metal from environment enter into water,settle down in sediment by adsorption,biological uptake,sedimentation and other ways,and finally accumulated and gathered. This give rise to the concentration of heavy metals in contaminated sediment are decades higher than that in overlying water. When sediment environmental conditions changed,the heavy metal in sediment will release again and contaminate the overlying water. Meanwhile,heavy metal is non-biodegradable,and has the characteristics of bioaccumulation,it bio-accumulates and concentrates by water food chain and finally have an effect on humanity. Since the complexity in chemical behavior and ecological effects of heavy metal,the governance and research on heavy metal in sediment is an unfailing question for study in environmental sciences during the past 20 years. In order to resolve the dredged sediments problems such as heavy metal pollution hazard and potential ecological risk,this paper take Suzhou river sediments for example,have research on species,contents,morphotypes,distributions and extraction toxicity of heavy metal in Suzhou river,study on adsorption of Cu/Zn by sediment,have an assessment on heavy metal pollution compared with related standards,experiment on Stabilization and leaching of heavy metal contaminated sediments,from the point of sediment pollution control. The Purpose of these experiments is to provide technical support and theoretical basis to sediment resource recycling. Following conclusions were achieved:Study on sediment adsorption characteristics and kinetics,through the sediment adsorption experiment on Cu/Zn. After fitting the experimental data, have a conclusion that the Sediment adsorption of the Zn and Cu meet Langmuir equation. Obtain theoretical maximum adsorption of Zn and Cu is 1044.79 mg/kg and 2055.58 mg/kg respectively. The first-class kinetics equation is more adequate for describing adsorption behavior of Cu2 + rather than Zn2 +.Have an assessment on sediment heavy metal pollution. Compared with foreign sediment quality standard,have a conclusion that the contents of heavy metal in Suzhou river sediment are over proof seriously.? Refer to? interrelated domestic standard about soil and mud used for farm,heavy metal pollution is moderate. Compared with soil background value,the contents of heavy metal in sediment is heavily greater than soil background value. After Comparison on heavy metal solidify and stabilization effect with different additives,results obtained are as follows: MgO is the best firming agents. Added 2.5%MgO,the concentration of Zn2+,Ba2+and Mn2+ in leachate reduced 80.91%,31.60%,65.07% respectively. Solidify sludge and calcium peroxide also had a good performance in heavy metal stabilization. Added 20% Solidify sludge,the concentration of Zn2+,Ba2+,Mn2+ reduced 84.21%,35.30%,64.52%;and with 5% calcium peroxide,the concentration of Zn2+,Ba2+,Mn2+ reduced 78.4%,55.51%,79.99%.Aluminum sulfate promoted curving of Zn and Ba, but also promoted leaching of Mn. Low consistency of sodium silicate have lower efficiency in curving,whereas high consistency of sodium silicate have higher efficiency in curving. Sodium silicate had a better effect in curving Zn and Mn rather than Ba. On the contrary,zeolite is good at curving Ba rather than Zn and Mn.This paper also experimented on heavy metal elution. Considering heavy metal morphotypes and distributions and evaluating leaching efficiency of different agents in different percentage,the experiment showed that citric acid is the most effective agent in heavy metal dissolution. The order of the leaching effectiveness is EDTA,tartaric acid,and PASP.