Energy Consumption Evaluation Of Landfill Leachate Disposal Using Electro-Fenton

The traditional process of leachate treatment is physical-chemical pretreatment＋biology body treatment＋physical-chemical advanced treatment, and the membrane filtration is the most widely used in advanced treatment. However, pollutants can be intercepted by membrane filtration but can not be completely removed, thus concentrates generated in membrane filtration will increase disposal load or even be a threat to the stability of the biology system. The Electro-Fenton treatment of landfill leachate ultrafiltration concentrates was investigated in this study, and the energy consumption and the current efficiency were discussed. The main conclusions are as follows:(1) The effects of pH, Fe2+ and current density on the treatment effect was exa mined by single factor experiment. The COD removel efficiency reached 61% under optimal reaction conditions that inclueded initial pH of 3.0, Fe2+ dosage of 1mmol/L, current density of 25 mA/cm2.(2) The process of treating landfill leachate concentrate by Fenton is in line with the pseudo first order kinetic model.(3) In F test, significance analysis showed the effect of 3 factors on the removal rate of COD:Fe2+ dosage> initial pH> current density; The interaction between the initial pH and the dosage of ferrous iron was very large, followed by the interaction between the dosage of ferrous iron and the current density, the interaction between the initial pH value and the current density is the least, the best experimental conditions of simulated cathode electro fenton method to remove garbage leachate is initial Ph=2.88, Fe2+ dosage 1.18 mmol/L、 current density 21.96 mA/cm2. Under the experimental conditions, the COD removal rate of landfill leachate was63.13%(4) Energy consumption and current efficiency under different voltages were analysized, and results show that when voltage is 10 V current efficiency droped from 50% to 30% and energy consumption increased from 5.6 kW·h/kgCOD to 9.7 kW-h/kgCOD in 60 min. It can be concluded that rate of COD degradation and current efficiency will decrease but energy consumption increases when time prolongs; rate of COD degradation becomes faster but with lower curent efficiency when voltage is higher; in 60 min, the best COD degradation and the lowest energy costs can’t be reached at the same time.(5) In addition, according to the NH3-N removal mechanism via indirect oxidation, Cl- concentration and NH3-N concentration changes regularly in Electro-Fenton reaction. Considering longer reaction time is required when NH3-N concentration reaches stable compared to COD, it will be more practical to take the removal efficiency of both COD and NH3-N into account to deter mine appropriate reaction time then evaluate energy consumption.