Post treatment of composting leachate using combination of aerobic completely mixed and plugs flow reactors

Today, collection and treatment of leachate is one of the necessary measures in the waste management. Leachate is defined as the aqueous effluent generated as a consequence of precipitation percolation through wastes, biochemical processes in wastes body and the inherent water content of wastes themselves. Leachate is not limited to the Landfill. It is also produces with considerable organic load in composting plants. Usually in treating of strong wastewater, anaerobic process is followed by aerobic methods to boost the process efficiency. The aim of this research was assessing the efficiency of aerobic reactors (plug flow & CSTR) to complete anaerobic method in treating of composting leachate. In this study the aerobic system was consisted of four concrete reservoirs. The first two of them was CSTR reactors which were paralleled. The dimension of each of them was 4×6×6.5 m with the effective volume of 163 m3. The second two (in order) were also paralleled plug flow reactors with the dimension of 13.3×2.5×3 m and effective volume of 89 m3. Wastewater was aerated by means of fine bubble diffusers at the bottom of each reactor. After each two paralleled reactors one sedimentation tank was also predicted. According to experiments the best food to microorganism ratio (F/M) in CSTR reactor was estimated in the range of 0.5-0.15. The average of COD removal efficiency was 80% in CSTR reactors, while ratio of MLVSS/MLSS was 55%. The average of SVI was also 100 ml/g in these reactors. In plug flow reactors with average loading rate of 0.32 Kg COD/m3.d the average of COD removal efficiency and MLVSS/MLSS was 37% and 57% respectively. The average of SVI was also calculated as 84 ml/g in plug flow reactors.