Bioremediation of Leachate from the Umlazi Landfill Site in KwaZulu-Natal

摘要

The aim of this study was to develop a cost-effective, biological treatment method for South African landfill leachate using a novel aerobic forced-upflow bio-reactor. Leachate from a moderately hazardous landfill site in Umlazi, near Durban, was used. The glass bioreactor comprised six chambers, each of which incorporated a fiberglass box filled with a support matrix on which a biofilm could develop. The suitability of pine bark as a support matrix was tested as it is cheap and readily available in South Africa. Six different grades or types were tested. Chemical Oxygen Demand (COD) was reduced by between 30% and 40%, while Total Carbon (TC) was reduced by between 66% and 75%. Nitrate levels remained low throughout the experiment, and the ammonia concentration eventually decreased, although it fluctuated greatly throughout the trial. Scanning Electron Microscopy (SEM) showed that substantial biofilm had developed on the surface of all pine bark types. However, the 16-24 mm pine bark chips were the easiest to work with and were therefore the matrix of choice. An experiment was also conducted to determine the type of aeration required in the system. Low to moderate aeration produced the best results with COD removal of up to 61%. High levels of aeration were not as successful: only 37% to 46% of the COD was removed. A COD reduction of between 43% and 45% was achieved when the system was not aerated. Ammonia levels were reduced by 98% in all aerated chambers of the bioreactor, but remained at fairly high concentrations in non-aerated chambers for most of the trial. This research shows that this low-technology approach can be successfully used to remove organic pollutants from landfill leachate.