Aerobic/Anoxic treatment of leachate from an active unlined landfill site: A case study

In this study, environmental investigations were conducted on the leachate collected from Al-Sulaibiya landfill site, Kuwait, to evaluate the leachate quality and treatment using aerobic/anoxic biological reactors in order to determine the degradation of organics and transformation of nitrogen. Results obtained show that leachate has high organic strength as expressed by its BOD and COD and high solids content. The COD average concentrations ranged from 795 mg/l to 1962 mg/l and the TDS maximum concentration was 23845 mg/l. The Aerobic/Anoxic (A/A) treatment of leachate in a semi-continuous reactor showed that the organic solids removal is generally high. After 30 days, 93% removal of COD was achieved. Nitrogen transformations by the nitrification and dentrification processes were observed, but the latter process progressed at a lower rate. The NO3- concentration in the reactor decreased from a maximum value of 750 mg NO3-N/L to a minimum of 300 mg NO3-N /L in 20 days. The effluent quality from the A/A digestion system has generally been excellent for COD, solids, and ammonia concentrations. Biodegradation of organics followed a first-order kinetic pattern.