Treatment of mature landfill leachate by chemical precipitation and Fenton advanced oxidation process

Mature landfill leachate is a complicated mixture which is resistant to biological treatment processes. The treatment of mature landfill leachate by struvite precipitation and Fenton oxidation was the main objective of the current research.
Struvite with the phosphate/ammonia/magnesium molar ratio of 1/1/1.05 was considered during all experiments. Five initial pHs of 3, 4, 5, 6, and 7, four different H2O2/Fe mass ratios of 50, 100, 200, and 400, and reaction times of 20, 40, 80, 120, and 160 minutes were examined for the Fenton oxidation process.
A leachate sample with average chemical oxygen demand (COD), BOD5, and NH4 concentrations of 7350, 2220, and 2280 mg L-1, respectively, and a BOD5/COD ratio of 0.3 was introduced to the chemical precipitation unit. An NH4 removal efficiency of 87% was obtained at pH 8.5 for struvite precipitation. Under optimum conditions of Fenton oxidation, including pH 3, an H2O2/Fe2 mass ratio of 200, and a reaction time of 160 min, more than 95% COD and BOD5 removal was observed.
Struvite precipitation and Fenton oxidation are reliable and efficient alternatives for mature landfill treatment.