Sorption Properties Of Chemicals In A Complex System To Organobentonite And Its Anti-seepage Performance In Landfill

Landfill is still one of the most important methods for disposal of municipal solid waste (MSW). Leachate is main secondary pollution of a landfill site. Many liners used in landfill has little effect on preventing the migration of organic contaminants. A sorptive landfill liner should be developed to control the potential risk caused by the leakage of organic contaminants. In this dissertation, the sorption properties of organic contaminants to organobentonite were investigated as well as the migration of contaminants through landfill liner in a complex solution. The self-cleaning abilities of the landfill liner materials were further investigated. The main original conclusions of this work are as follows:(1) The coexit organic contaminants in leachate would increase the ability of landfill liner in preventing the migration of organic contaminants, while heavy metal, colloids and salt in leachate showed a negetive effect in retarding the migration of organic contaminants through liner. The sorbed organic pollutants would increas the sorption ability of organobentonite. The removal rate of 6 chemicals to CTMAB-bentonite would increase to 3.99-11800 times and show a negative relation with their molecular size when they coexisted. Heavy metal would appear a competitive adsorption on the siloxane surface of bentonite against organic pollutants. The colloid in aqueous phase would increase the distribution of organic pollutants in solution. Salt would occoupy the adsorption site of bentonite and limit its swell ability. The removal rate of chemicals by CTMAB-bentonite would reduce more than 50% when the concentration of salt was 0.5 mol/L.(2) The increase of pressure above liner would raise its ability in preventing the migration of organic pollutants,while a higher temperature appeared a negetive effect.The pressure could compact the bentonite liner and lower its hydraulic conductivity.When the pressure on the liner increased to 17.4kPa, the hydraulic conductivity of the 15g liner decrease more than 25%,resulted in a raise of its ability in preventing the migration of contaminants. The increase of temperature would limit the sorption ability of contaminants to organobentonite and increase the hydraulic conductivity of linr, which resulted in a reduction in preventing the migration of contaminants. One dimensional mass transfer model could fit the transport of organic contaminants through bentonite liner well.(3) A method of efficiently retarding the migradation of organic contaminants in landfill leachate and followed an in-suit degradation was developed, which could maintain the structure of landfill liner material as well as its sorption ability. In this instance, the self-cleaning ability of landfill liner could be achieved. Combines use of zero-valent iron and CTMAB-bentonite could remove various kinds of organic contaminants in aqueous. The removal rates of 5 chemicals were all more than 97%when zero-valent iron and CTMAB-bentonite were applied simultaneously. The sorption ability of CTMAB-bentonite could be released and the structure of CTMAB-bentonite would be remained. The coexist salt and humic substance in leachate confined the sorption ability of organic contaminants and further limit the ability in self-cleaning of landfill liner.