Anaerobic treatment of landfill leachate

Abstract

Anaerobic technologies are the most suitable treatment processes of the landfill leachate, and offer advantages, that is, application of high organic loading rates (OLRs), low operational costs, and biogas productivity. However, the efficiency of anaerobic reactors are highly dependent on the temperature, OLR, ammonia loading rate, sludge loading rate, and reactors configurations. Those factors affect the microbial activities, hydrolysis of leachate and enzyme activities. Moreover, the anaerobic reactors are subjected to biomass washout that impairs the efficiency of the technology. Therefore, intentional sludge discharge is necessary to control the food-to-substrate ratio that highly affects the performance of anaerobic process. The removal of organics is quite high (>90% of BOD) from the leachate by anaerobic digesters where low requirement dose of phosphorous are needed for anaerobes growing, low excess sludge productivity, low energy consumption, and usage. Moreover, the technology produces hydrogen and methane from leachate. Nevertheless, the presence of high concentrations of ammonia in the leachate could highly inhibit the anaerobes and leads to process failure. Therefore, two-stage anaerobic reactors are recommended at low OLR to achieve a good effluent quality complying for discharge and/or reuse.