Study On Purification Process Of Organochlorine Pesticide β-HCH In Subsurface Flow Constructed Wetland

Organochlorine pesticides(OCPs)are a class of typical persistent organic pollutants(POPs),domestic and international research scholars in the environment of the various media for organic chlorine residue detection,the results found that although organochlorine pesticides were banned production and use of nearly three more than a decade later,a variety of organochlorine pesticides were still detected,of which β-HCH accounted for a higher residual ratio.Organochlorine pesticides are difficult to degrade and lipophilic hydrophobicity determines that it can enter the human body through the food chain,and endangering human health.The scientific community has been exploring effective ways to treat organochlorine pesticide residues,while constructed wetlands are considered to be one of the effective ways to treat organochlorine pesticide contamination.In this paper,β-HCH was used as the purification target,and the purification process of organochlorine pesticides was studied by static and dynamic simulation of natural wetlands.The purification process of β-HCH under different wetland plants and different operating conditions was discussed.Artificial wetland to remove the organochlorine pesticide mechanism,in order to further study the artificial wetland in the future treatment of residual pesticide in water to provide a scientific basis.The main conclusions of this paper are as follows:(1)Four sets of static subsurface flow constructed wetland simulator were used to investigate the process and effect of β-HCH purification in different plant artificial wetlands under the same substrate.The treatment concentration of β-HCH was 15 μg / L,and the blank control group was set up.The results showed that β-HCH could be effectively removed in the four wetland simulation systems for 59 days.The removal rate was as follows: iridium model group> re-flower model group> canna group model group> blank control group.The removal rate of the model group was 94.90%,93.40%、92.32% and 84.36% respectively.The SPSS software showed that the removal rate of β-HCH was not determined by the artificial wetland model group There are significant differences.The removal rate of the blank control model group was only 84.36%,which indicated that the substrate in the constructed wetland played an important role in the purification of the pollutants in the whole wetland system.The wetland plants could promote the wetland system The effect of β-HCH purification.In the early stage of the constructed wetland,the matrix adsorption is the main way to remove the β-HCH in the constructed wetland.In the 3d,about 80.0% of the β-HCH in the water is adsorbed into the matrix.The water quality index in the wetland measured during the test run is not directly related to the purification effect of β-HCH,but only reflects the water quality of the constructed wetland system and the growth environment of the wetland plant.(2)To build five sets of static artificial wetland simulation device,recorded as CW1 ~ CW5,CW1 is a no wetting plant and no plant wetland device,CW2 is a plant only wetland device,CW3 is a filling only the wetland device,CW4 is a wetland device with matrix and plant,but added ampicillin to inhibit the microorganism,CW5 is a matrix and plant wetland device,without adding any inhibitor.The optimum concentration of β-HCH was as follows: the concentration of β-HCH was 25 μg / L,and the treatments of wetland plants,substrates and microorganisms were studied in five sets of artificial wetland plants.The degradation process and effect of β-HCH in sewage were analyzed,and the degradation curves and half-life of β-HCH were analyzed.The results showed that the scavenging ability of β-HCH was higher than that of wetland plant and matrix adsorption in the combination of plant and substrate in constructed wetland system.Artificial wetland cultivation of calamus can significantly improve the degradation efficiency of β-HCH,and in the experimental cycle of microbial degradation of β-HCH is not obvious.Under the static condition,the degradation process of β-HCH in CW1 ~ CW5 five sets of artificial wetland small test device accorded with the first-order degradation kinetic equation.The degradation equation is:(1)c = 5.7094exp(-0.117x)+ 18.9898,(2)c =12.630 exp(-0.284x)+ 10.1098,(3)c = 18.047exp(-1.3439x)+ 6.5203,(4)c = 21.283exp(-1.0912x)+ 2.6978,(5)c = 23.194exp(-1.2124x).The half-lives of β-HCH in CW2 ~ CW5 were 148.56,20.16,18.00,15.12 h,respectively.The half-life of β-HCH in CW1 was still not due to the short-period project.(3)In the static artificial wetland experiment,the effect of artificial wetland on the β-HCH treatment was gradually reduced with the increase of β-HCH concentration loading.the purification efficiency of β-HCH was increased with the increase of hydraulic loading(300,900,900 mm/d)under dynamic continuous operation condition.The effect of β-HCH on M-300,M-600 and M-900 were in accordance with the first-order degradation kinetic equation,and the degradation equation was:(1)c = 19.748exp(-0.8433x)+ 3.6907,(2)c = 21.397 exp(-1.4638x)+3.3356,(3)c=22.188exp(-1.5218x)+2.5965.The degradation half-lives were 24.96,14.16 and 12.96 h,respectively.