Technology Research About Remediation Of Contaminated Sediment By Capping Biochar Amendments

The pollution of sediments is a global environmental problem, and due to the accumulation of pollutant in sediment, the pollutants in the sediment concentration higher than the overlying water 2-3 orders of magnitude. The pollutants in contaminated sediment can go into human’s body through the food chain and food webs in the biological enrichment, which bring serious effection to human’s health。 Because of traditional remediationof contaminated sediments do not always achieve the goals,the study of new approach and management of contaminated sediment and repairing technology become a global hot issue. The technique used in this research is in-situ remediation of contaminated sediments with amendments. The amendments used in this research are coconut shell powdered AC、coconut shell large granular AC、 coconut shell small granular AC、charcoal AC、plant ash and nut shell AC.The target pollutant is BETX、PAHs and PAEs.This research includes four parts:physical and chemical properties characterization of amendments;The laboratory simulation experiments about in-situ remediation of contaminated sediments;the dynamics experiment of repairing contaminated sediments;the field experimentation in puhe about remediation of contaminated sediment using thin-Layer capping with amendments.The main research results are as follows:1)physical and chemical properties characterization of six kinds of amendments: from the scanning electron microscopy diagram,we can see that the pore structure of five kinds biocharis ordered and looks like honeycomb; the plant ash’s is distribution.the result of surface areas are as follows:the surface area of six kinds amendments have great difference. The surface areas of Coconut shell powdered AC is 1541.29 m2/g, and Plant ash’s is 13.53 m2/g. The surface area of Coconut shell powdered AC is more 100 times larger than plant ash’s.The pore size distributions of Coconut shell powdered AC、Charcoal AC、Coconut shell large granular AC and Coconut shell small granular AC have no much different.The rate of microporous and mesoporous is almost 95%.And Nut shell AC’s is 86.86%;and the plant ash’s is 67.33%.The result of IR spectra show that surface functional group of the amendments have no much difference.They all have - OH、-CH3、-NO2、C-F、=CH2 and C=C。 And the Coconut shell small granular AC also have C-O and -C=O.And Charcoal AC have -CH3 and C-O-C。2) The laboratory simulation experiments about in-situ remediation of contaminated sediments:After 10 month amendments remedationthe pollutants in sediment has good removal rate.The removal rate of using Coconut shell powdered AC is the best, almost reached 100%.The efficiency of plant ash removal is minimum, around 80%.The removal rate related with the physical and chemical properties of amendments, especially the surface area. The decrease rate of three kinds of pollutants in sediment results showed that different amendments have different. For coconut shell AC and Nut shell AC,the removal of polycyclic aromatic substances, the second is the benzene series, finally is the phthalate esters.For plant ash,the removal efficiency of PAEs is the best. Experiments also show that under the condition of lowflow rate,the water will not much affect the remedation.3) Fitting the remedation of contaminated sedimentwith first order kinetics and the secondary dynamic equation.The result is the remedation behavior more suitable for pseudo-first order kinetic equation.According to the secondary dynamic equation to calculate the coconut shell powder AC’s adsorption capacity is 2777 ug/kg,and plant ash’s is 872 ug/kg.4) To measure the contaminant concentrations of Pu river,andaccording to the potential hazard index method to determine the priority control pollutants of pu river.After 5 months remedation with three kinds of amendments(carbon,coal based AC and Nut shell AC), the pore water concentrations of benzene, PAHs and PAEs were significantly reduced. The fixation efficiency of nut shell AC in field experimentation compared with the laboratory experimental show that the fixed removal efficiencies about benzene and PAHs have no big difference.Maybe because of the measurement error, the removal rate of PAEs’in field experimentation is higher than the laboratory experimental’s(The concentration of PAEs in laboratory experiments of sediment is in close to the instrument detection limit, and the concentration of PAEs in field experimentation 2 to 3 orders of magnitude higher than the detection limit...