| The methods of deposing waste mainly include incineration, composting,landfill and so on. As a result of large quantity, low cost, mature technology, sanitarylandfill has been widely used at home and abroad. But it can produce great harm oflandfill leach ate. In addition, it contains high COD, BOD5, ammonia nitrogen and allkinds of heavy metal ions, etc, complicated composition, high salinity and poorbiodegradability. In the treatment of landfill leach ate especially using biologicalmethod. It is necessary to use the pretreatment of physic-chemical method. It canremove part of organic matter, reduce the biological toxicity of landfill leach ate, alsoplay a significant role for the following biochemical treatment. So studying thepretreatment of landfill leach ate has important theoretical significance and also canguide the engineering practice.Regarding the landfill high-salinity waste leach ate as the object of the researchin this paper. the composite coagulant method, Fenton oxidation method, activatedcarbon adsorption method have been used in the pretreatment of landfill leach ate.For composite coagulant pretreatment of landfill leach ate, the polyaluminumchloride and polyacrylamide have been as the composite coagulant. The experimenthas examined the effect of the dosing of PAC and PAM, the dosing time of PAM onCOD removal efficiencies. The test is divided into two parts of the single factor andorthogonal experiments. The experiments results show that the optimal coagulationconditions are PAC dosage of1050mg/L and PAM dosage of0.8mg/L, and addingpolyacrylamide(PAM) seven minutes after the dosage of polyaluminiumchloride(PAC). And in the optimum conditions, The value of COD decreased from4876mg/L of the raw leach ate to2402mg/L, the removal rate of COD reached50.74%, and the chromaticity of the landfill leach ate has been removed aftercoagulation.As for Fenton oxidation pretreatment of landfill leach ate, the experiment hasconfirmed the optimum reaction conditions of Fenton oxidation, through theorthogonal experiment, the dosing quantity of H2O2, the dosing quantity ofFeSO4·7H2O, pH, reaction time are the main factor affecting Fenton oxidation,Through single factor experiment, the optimum value of the various factors have been determined. The optimum test condition of Fenton oxidation treatment of landfillleach ate is: the dosing quantity of H2O2is8mL/L, and the dosing time of H2O2hasbeen divided into three times, the initial pH of the landfill leach ate is three, thedosing quantity of FeSO4·7H2O is0.8%, the reaction time is2.5hours, after Fentonoxidation treatment, The average concentration of COD decreased to1707mg/L, bycalculating, the removal rate is65%, the chromaticity of the supernatant fluid reducedfrom4000of raw water to2000times.In the adsorption stage, the powder activated carbon has been used as adsorbent,the test show that the powder activated carbon can be directly used for treatment ofhigh concentration of landfill leach ate, and it also has certain removal rate of COD,NH4-N, total phosphorus. Take the coagulation effluent of the best coagulationcondition in the composite method for adsorption experiment, the optimum dosage ofpowder activated carbon is12g/L, and the optimum adsorption time is five hours.Under this condition，it has relatively high removal rate of COD and total phosphorus,the removal rate of COD and total phosphours are69.2%and38.4%respectively, butit is not obvious for the removing of NH4-N. Take the effluent of the best Fentonoxidation for adsorption experiment, the study showed that: the optimum dosage ofactivated carbon is4g/L, and it can remove part of COD, total phosphorus andNH4-N, however, when the pH value is4, the adsorption effect is best for COD andtotal phosphorus, under this conditions, the removal rate of COD is73.8%and thetotal phospgorus is45.1%, but the higher pH value, the better removal rate of NH4-N,it can make the NH4-N removal rate reach the highest when the pH value is8. thehighest ramoval rate is32.5%. |
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