Study On Landfill Leachate Treatment By Composite Process Of Iron-carbon Micro-electrolysis, Magnesium Ammonium Phosphate(MAP) And Biological Method

Sanitary landfill is the main method of the municipal refuse treatment, and it can produce landfill leachate that is very harmful to environment. The landfill leachate is a complex wastewater with considerable variations in composition, and high concentration of COD, heavy metal ion and ammonia-nitrogen, and pollutants concentration change largely. The water, the soil and groundwater environment will be polluted severely polluted if landfill leachate is discharged into the environment. Currently, all of the landfill leachate treatement process in domestic and foreign can be divided into three segments; the biological treatment is taken as the main process, the physical-chemical treatment and land method are taken as the pretreatment process and the post-processing process, respectively.This study investigate the feasibility of united biological and physic-chemical treatment technology to treat the Hefei Longquan Mountain landfill leachate. "Anaerobic Baffled Reactor (ABR) - Cyclic Activated Sludge System (CASS)" process is designed as the main treatment technology, "Iron-carbon Micro-electrolysis and Magnesium Ammonium Phosphate (MAP)" process is acted as the pre-treatment step. The physical chemistry and biological chemistry treatment technology of "iron-carbon micro-electrolysis, MAP precipitation, Cyclic Activated Sludge System and Anaerobic Baffled Reactor" is determined in this paper. The conclusions are as follows:(1) In the Iron-carbon Micro-electrolysis process, the removal rate of COD_cr is 47.5%,when the Fe/C=5:1, pH=3.0, reaction time(t)=3hours.(2) In the Magnesium Ammonium Phosphate (MAP) process, the removal rate of NH₃-N is 79.7%,when n(Mg²⁺):n(PO₄^3-):n(NH₄⁺)=1.4:1:1, pH=9.0, reaction time(t)=1hour.(3) COD_cr removal rate of Anaerobic Baffled Reactor (ABR) reached more than 70% at room temperature, when the hydraulic retention time (HRT) is one day.(4) COD_cr removal rate of Cyclic Activated Sludge System (CASS) process reached 65% and ammonia nitrogen removal rate reached 80% at room temperature, when the hydraulic retention time (HRT) is one day. The results show it is feasible to use "iron-carbon micro-electrolysis, MAP precipitation, Cyclic Activated Sludge System and Anaerobic Baffled Reactor" to dispose of the landfill leachate. The quality of effluent also can reach the second grade of Domestic Landfill Pollution Control Standard.