Processing leachate from municipal solid waste landfills for further utilization

Summary

The operation of municipal solid waste landfills produces a negative impact on the environment. The landfill leachate contains high concentrations of mineral and organic substances and, according to many researchers, is highly toxic. The qualitative characteristics of leachate depend on the age of the landfill, climate conditions and season of the year, amount of atmospheric precipitation, fallout pattern and other factors. Undoubtedly, the leachate quality is determined also by the chemical composition of wastes disposed to the landfill. Leachate handling is an urgent problem. Most often leachate treatment to the effluent quality meeting the maximum permissible concentrations for fishery waters is suggested. All the technologies and methods of this direction are fairly complicated and expensive. As a result additional wastes reluctant to utilization are generated. The possibility of using leachate for the landfill irrigation is suggested for consideration. This is the best practice since the effluent is retuned back to the landfill solid which is a natural biological reactor. Pretreatment, leachate saturation with oxygen and its further use for landfill irrigation will provide for reducing the time needed for complete destruction of organic compounds to the formation of humic acids, humate and organic soil; and also reducing significantly the negative impact of landfills on the environment including aquifers. In this case most of leachate evaporates and goes to the atmosphere eliminating any serious impact on it.

Key words

cleansing , filtrate , organic substances , environment , municipal solid waste landfill , recycling , aerobic process

Natural materials for sorption purification of chrome
and cadmium-containing leachates of solid waste landfills

Summary

The analysis of the sorption characteristics of natural materials (vermiculite, expanded clay, perlite, «Trade» zeolite) during the purification of cadmium and chromium-containing leachate with a high COD load was carried out. It was determined that zeolite had the maximum sorption capacity for Cd and Cr and the lowest biological fouling. When using vermiculite and expanded clay or mixtures on their basis, one can expect an increase in the sorption capacity for Cd and Cr during microbial fouling that inevitably occurs during contacting with water polluted with organic compounds and nutrients. In this case biofouling can increase the immobilization properties of materials for redox-dependent metals due to the enzymatic resources of bacterial cells that use them as electron acceptors. The effect of microbial fouling changed the parameters of materials in different directions: for Cr, in most cases, downward, and for Cd, significantly upward. Moreover, chromium biological recovery by biofilms is an additional effect of immobilization. Varying the composition of the sorption material provides for selecting mixtures that are optimally suitable for the purification of leachates from solid waste landfills with high COD and nutrients load, both when used in situ and in surface systems.

Key words

zeolites , municipal solid waste landfill , biosorption , infiltrate , vermiculite , expanded clay , perlite , cadmium , chromium , biological recovery , permeable reactionary barriers