PHYSICAL AND CHEMICAL TREATMENT OF A NITRIFIED LEACHATE FROM A MUNICIPAL LANDFILL

Leachate from a Swedish municipal landfill in the methanogenic phase w as nitrified and then treated by various physical and chemical methods : oxidation with Fenton's reagent and with ozone, precipitation with f erric chloride and with aluminum sulphate and adsorption onto activate d carbon. The leachate was analyzed by measuring the COD (chemical oxy gen demand), the BOD, (biochemical oxygen demand) and the TOC (total o rganic carbon). Specific organic compounds were analyzed by GC/MS (gas chromatography and mass spectrometry) while the molecular weight of t he organic matter was determined by ultrafiltration. The nitrification process resulted in 20-30% of the COD being removed. The maximum COD removed after nitrification and oxidation was 80% using Fenton's reage nt and 54% using ozone. The combination of nitrification and precipita tion gave a maximum COD removal of 68% using ferric chloride and 54% u sing aluminum sulphate, while nitrification and adsorption onto activa ted carbon gave a maximum COD removal of 76%. A combination of nitrifi cation, precipitation with ferric chloride and adsorption on activated carbon gave a TOC removal of 96%. The ultrafiltrations showed that ni trification and adsorption onto activated carbon were the most efficie nt processes for the removal of low molecular weight compounds. The GC /MS analyses showed that, for instance, C-3-substituted benzenes and C -2-C-4 substituted phenol isomers were degraded during the nitrificati on process, while phthalates were unaffected even after treatment with Fenton's reagent or by adsorption onto activated carbon.