Study On Solidification And Disposal Technology Of Hazardous Waste Landfill Leachate

The hazardous3 waste landfill leachate(HWLL)has typical characteristics such as high salinity and organic concentrations,strong toxicity,and poor biodegradability,and needs urgent safe disposal.This study aimed to explore a feasible new disposal technology for HWLL and the similar wastewater by using the HWLL from a hazardous waste landfill in Shaoxing,Zhejiang Province.Characterization of the HWLL quality,optimization of solidification treatment,and evaluation of simulated landfill behavior were sequentially carried out.The analysis of water quality characteristics showed that the HWLL was a kind of extreme refractory wastewater with high salinity and organic concentrations.The water quality was complex and fluctuate,the pH could gradually change from acidic to alkaline and the COD concentration could reach to 35000 mg/L during the landfill process.Moreover,the salinity could greatly fluctuate from 60 g/L to 150 g/L as the rainfall.The pH would significantly increase in rainy and high temperature seasons,while the COD concentration correspondingly decreases.The further solidification disposal showed that it is feasible to co-solidify the HWLL by using cement,metakaolin,diatomite,activated carbon,and glass fiber together.It had the best solidification behavior when the curing agents including cement and metakaolin,and the additives likes diatomite,activated carbon,and glass fiber were controlled at 58.1%,38.7%,0.48%,0.24%,and 2.4%under the solid-to-liquid ratio of 1,respectively.The highest fixing rates of COD and salinity could reach to 95.1 ± 1.6%and 87.1 ± 1.5%,respectively.The leaching water quality from the curing blocks under the optimal solidification conditions could meet the first-class B standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB18918-2002).The solidification process shows very low secondary pollution risk.Finally,the simulated landfill behavior evaluation of HWLL curing blocks further proved the feasibility and long-term validity of the solidification disposal method.The HWLL curing blocks could safely stay for long-term without deformation inside the landfill.All kinds of pollutants could be firmly restrained in curing blocks and the leaching water quality could reach the first-class B standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB18918-2002).The packaging modes had certain effect on the pollutants releasing from the curing blocks.The pollutants releasing from the curing blocks with packaging was slower than those without Theoretically,it will cost 38 years and 75 years for the releasing of the total salt and organic from the curing blocks with packaging,while that for curing blocks without packaging will be 34 years and 49 years,respectively.This study provides a feasible method for hazardous waste landfill leachate treatment.It also provides alternative choice for similar refractory wastewater treatment.