THE USE OF NATURAL MATERIALS FOR THE TREATMENT OF LEACHATES OF THE AGADIR DUMP

Abstract

Within the perspective of adopting effective solutions to the problems related to the burial of urban waste and its resulting harmful effects on both the environment and the human health, suitable actions should be taken to remedy the shortcomings of this somehow primitive method of waste disposal, namely those of the generated leachates. Because of their high pollutant load, leachates have to undergo a treatment of purification before being discharged into the environment. The focus of our study is to develop a simple technique to reduce the pollutant load of leachates in the technical burying center (TBC) of solid waste in Tamellast, Grand Agadir. This technique is based on the treatment of leachates through aeration followed by a percolation-infiltration on sand. The sand used is raw titaniferous sand (RTS) which is very abundant in the region of Agadir. Young leachate samples issued from fresh urban waste were collected at TBC, Tamellast. The physicochemical analyses of the young leachates show that their pH is very acidic, the values of conductivity are very important and greatly exceed the normal limit value specified for the discharges (2.7 mS / cm). The levels of biodegradable organic matter are important (the COD and BOD5 values are 17800 mg of O2 / L and 9100 mg of O2 / L, respectively). The aeration of leachate by injecting air has increased electrical conductivity due to the different chemical and biological reactions involved in the treatment. However, the values of COD and BOD5 have decreased. This decrease shows the significant effect of aeration on the reduction of polluting organic matter. The ratio BOD5 / COD is greater than 0.5 and shows that the treated leachate is of a very good biodegradability. After aeration, the young leachate was infiltrated by percolation on a sand column. The BOD5 value reached 280 mg of O2 / L (the BOD5 limit value of direct discharge = 300 mg of O2 / L) and the COD value is 540 mg of O2 / L (the limit value of direct release COD = 600 mg of O2 / L). The technique developed in this study led to high abatement rates (96.96% for COD and 97% for BOD5) in organic matter and lower COD and BOD5 values.