The Research Of Landfill Leachate’s Pre-Treatment With Magnetic Coagulation-Magnetic Separation Technology

Garbage sanitary landfill is one of the most wide spread method of the city garbage treatment,then forming the landfill leachate.The landfill leachate is great damage to the environment for its nature and complex composition.In the treatment technology of landfill leachate,coagulation can adapt to the continual change in the composition of leachate and can steadly remove most of the pollutants.This research mainly takes the landfill leachate from Nanning Shanglin Landfill as the object,the NH3-N and COD as the index,with magnetic coagulation-magnetic separation technology as a pre-treatment process.It determines the optimal coagulation agent,magnetic coagulation condition and magnetic separation condition through carrying out the test of the coagulation agent selection and the conditions optimization.This test has been made on above factors that affect the treatment efficiency such as dosage,mixing method,temperature,pH value,magnetic field intensity,water flow velocity,etc.Then the datas determine the optimal process condition in the treatment of above landfill leachate;and the process of filtering properties of mud mixture has been explored.The experiment results show that Polymeric Ferric Sulfate(PFS)is the best coagulant in above landfill leachate treatment,and aeration treatment can effectively remove 60%NH3-N and 25%COD.Processing the landfill leachate after aeration,the optimal condition of magnetic coagulation-magnetic separation is as following:25℃,a pH value of 10.0,a dosage of PFS 16 g·L-1,a dosage of magnetic seed 30 g·L-1,with a mixing method 250 r·min-1 for 4 min 100 r·min’1 for 15 min,a dosage of PAM 20 mg-L’1,magnetic field intensity 150 mT,water flow velocity of 0.5 L·min-1.In such condition,the removal rate of COD can reach 86.8%,the content is 486 mg·L-1,and NH3-N removal.rate reach 75.6%,its content is 196 mg·L-1.In which,magnetic coagulation technology plays a main role in the removal of NH3-N and COD,and the magnetic separation technology has the further removal efficiency of them hardly.The research results of filtering characteristics show that when the sludge setting to the same volume,the time magnetic coagulation cost is 3.4 times faster than coagulation.After sedimentation for 60 min,the magnetic coagulation sludge volume is less than coagulation nearly doubled.The-sludge specific resistance is 613 times smaller than coagulation,and the filter constant value is 2.85 times of coagulation.So,the magnetic coagulation is easier to filter.The magnetic seed can strengthen the coagulation effect.The magnetic seed not only can be used as the core of flocculating,enhanced flocculation sedimentation effect,also make the floccules gain strong magnetic leading its realization of solid-liquid separation in the magnetic field and the improvement of the separation efficiency.Magnetic coagulation-magnetic separation technology can effectively remove the content of NH3-N and COD in the landfill leachate.This technology has many distinguishing feature for hign processing efficiency,good separation effect,simple equipment,covering the less area,easy to realizing integration,automation,etc.It has a broad application prospect in the field of sewage wastewater treatment.