In this study, the effect of adding clay minerals and/or wastewater treatment-plant sludge (WWS)
to organic fraction of municipal solid waste (OFMSW) in simulated landfill reactors was investigated. The clay
minerals and/or WWS were directly co-disposed with solid waste in the laboratory to determine an alternative
and effective method for, sludge and solid waste, digestion and disposal. As well as to increase biogases
released and improve the quality of the leachate. Two types of models have been used, bench scale models and
pilot scale models. The WWS used was a mixture of primary and waste-activated sludge. sludges were supplied
from Zinien, a municipal wastewater treatment plant located in Giza. A powdered montmorillonite clay were
prepared and supplied. Two sets, each of seven bench scale models were designed and placed in a temperaturecontrolled
water bath. The first set loaded with clay and OFMSW at ratios ranged between 15% to 80% by
weight of solid waste to determine the optimum clay-solid waste mixing ratio, The cell receiving 40 % Clay
mineral achieved the maximum amount of biogas. The second set loaded with 50 % WWS, OFMSW and
different clay ratios ranged between 15% to 80% by weight of solid waste to determine the optimum clay-solid
waste mixing ratio. The best mixing ratio that achieved the maximum amount of biogas, was which has 30%
clay. Pilot-scale simulated landfill bioreactors were designed, constructed and loaded with solid waste, sludge
and/or clay at the best ratios that obtained from the first two sets. In order to assure the previous results and to
investigate the effect of pilot scale, leachate collection and recirculation on the degradation of the organic
wastes. The stabilization of organic waste in the reactor receiving the mixture of WWS and clay was faster, as
indicated by the total gas production and the leachate COD removal. On the other hand, the bioreactor receiving
the mixture of clay only with OFMSW achieved better results than that receiving the mixture of WWS with
OFMSW, in meaning that clay minerals may be used instead of the WWS to enhance the solid waste
degradation in the landfill. Moreover, clay minerals more clean and has less impact on the surrounding
environment. |
