Comparative studies of landfill leachate treatment using aerobic, anaerobic and adsorption systems
Landfill leachate with its variable and complex characteristics poses a well established threat to the environment. Enhancement of the environmental quality through the minimization of the leachate problem should therefore be the major objective of good landfill management. The need to control and manage landfill leachate has resulted in various treatment alternatives which include both biological and physical-chemical processes. The research described in this thesis discusses the feasibility of biological and physical-chemical treatment of leachate based on laboratoryscale reactors. After a short introduction, a review of the relevant literature on solid waste disposal including landfilling, leachate generation and the treatment alternatives was presented. Comparative experimental studies were then carried out using an aerobic rotating biological contactor (RBC), an upflow anaerobic filter (UAF) and an activated carbon (AC) adsorption column for treating landfill leachate. The effect of a range of parameters on the performance and operation of the RBC, the UAF and the AC column has been evaluated in the study From the experimental results, an RBC was found to achieve a better performance when treating a low strength (LS) leachate, whereas a high strength (HS) leachate would be much better treated by a UAF. For the LS leachate treatment, a COD removal of 80% at a loading rate of 6 kg COD/m3.d was achieved by the RBC as compared to only 60% by the UAF. Whereas for the HS leachate the RBC achieved a COD removal of only 50% at the loading rate of 14 kg COD/m3.d as compared to 60% by the UAF. Direct physical-chemical treatment process in treating leachate using an AC adsorption was also investigated. The results obtained showed that the adsorption process was not capable of achieving the desired effluent requirement, with 20% residual organic fractions still remaining in the effluent. The need to remove this biodegradable organic matter by biological processes was found to be necessary. It is suggested that to achieve satisfactory treatment, anaerobic UAF treatment of leachate followed by aerobic RBC and a final polishing with AC column should be used.