Ecological Toxicology Study On Modified Zeolite Remediation Of Landfill Leachate Polluted Soil

At present, China is in a period of rapid development, urbanization and livingstandards are constantly improving, production of municipal solid waste has alsoincreased. With the gradual expansion of the urban planning area, many of the old landfillhas been in urban planning and construction area or even within the core area, due to thelack of or inadequate anti-seepage system, leachate infiltration into the soil andgroundwater, damaging the living conditions of soil microorganisms, having adverseconsequences on soil structure and soil, increasing soil heavy metal pollution, causingplant growth and development crisis, and even pollution of groundwater, posing a seriousthreat to a high degree of aggregation of the population of urban air quality andgroundwater resources, but also a large number of waste of urban land resources.Based on the chemical adsorption theory and ecological means of experiments inlaboratory conditions to simulate the use of modified zeolite ectopic chemical remediationof soil contamination, focusing on developed a chemical remediation of soil contaminatedleachate new method, the experiment add different modification conditions and weightratio of zeolite, and using Tetrahymena pyriformis toxicological experimental method toevaluate the repair effect on leachate contamination yellow brown soil. The mainconclusions include the following:(1) A single modification of the repair under the conditions of microwave treatmenteffect is better than acid treatment, Tetrahymena pyriformis24hLD50diagnostic testresults show that when using a single microwave processing,15g of zeolite dosage is thebest;3min of microwave processing time is relatively better. When using acid treatment,death rate of some groups is higher than the control group and even close to100%mortality. Tetrahymena24hLD50has no obvious relevance with zeolite doze, comparingwith others found that8mol/L HCl concentration has a better impact.(2) Under the conditions of Microwave-acid combined modified, Tetrahymenamortality analysis indicates that the restoration effect of microwave treatment before theacid treatment is better than the first acid treatment and then microwave. Consistent with asingle modification,15g dosage is best in the restoration. Mortality death of first acid treatment groups were100%. Chronic toxicity test results show that first acid-treated thenmicrowave treatment OD600change is slow, no significant logarithmic phase, directlyinto the stable; and first microwave treatment then acid treatment, the zeolite compared tomodified prior to the restoration program have good results.(3) Under the combination of modified zeolite and cow dung, Tetrahymena acutetoxicity studies show that after the addition of cow dung Tetrahymena death rates havedropped significantly. When a certain amount of added cow dung, the more the amount ofzeolite added, the lower the death rate is. Chronic toxicity studies show that through thejoint action of microwave treatment and cow dung, each group of OD600Tetrahymenahas a more substantial increase, and has a longer logarithmic growth phase, to prove thatsoil leachate chronic toxicity of biological is lower under this condition.(4) Microbe cultivation results show that repair through modified zeolite, certaintypes of microorganisms became dominant bacteria, indicated that the modified zeolitecan change the soil micro-environment for a number of micro-organisms to provide betterliving conditions. Molecular ecology results show that the level of each group in the DNAdifferences is small, DNA fragments are concentrated in the1375~2027bp.