Combination Of Biochemical And Physico-Chemical Technology Research For Different Periods Of Landfill Leachate Treatment

Landfill leachate contains a variety of pollutants such as organic mater and high concentration of ammonia,which often change with time and weather.Treatment of landfill leachate is a focus of researcher's attention as well as a difficult problem in field of wastewater treatment.Generally,landfill leachate is treated mainly by biological or biochemical process at present.Moreover,some researchers carried out the new treatment technics,such as elestrolytic oxidation and catalytic oxidation.But until nowadays it is not found an effective way to resolve the problem.The paper was carded out to investigate the typical landfill leachate.Aiming at the different change of water quality between the early landfill leachate and the long-term landfill leachate,the different treatment technics were adopted.The early landfill leachate used "air-stripping as the pre-treatment step,the long-term landfill leachate add the micro-electrolysis to improve the biodegradability,"UASB-A/O" was designed as the biological treatment,"coagulation or Fenton oxidation" for the early landfill leachate was operated as the post-treatment step,the RO technics for the long-term landfill leachate replaced the Fenton oxidation to meet the diposal demand. It also sudied the best operation index of every process.The main conclusions are as follows:(1) The "air-stripping" was used as the pre-treatment step of nitrogen removal. Under the condition of pH=11,the gas to liquid ratio=3300-3500,temperature of 25℃, hydraulic retention time(HRT) =1-2h,the removal rate of ammonia could reach more than 90%.(2)The combined iron-carbon Micro-electrolysis and H₂O₂ experimental results showed that when pH was 2.7,the reaction time was 1h and Ferric-Carbon quality rate was 3:1,the removal rate of COD in raw wastewater was 33%,the study also analyzed the change of iron surface in the reaction process and investigated the makeup of surface matters.;When the dosage of H₂O₂(30%) was 1mL/L and the reaction time was 30 minutes,the removal rate of COD was raised to above 70%,the decoloration rate of was above 90%,the effluent BOD₅/COD ratio increased from 0.23 to 0.68.(3)Under the temperature of 25℃,HRT was 24 h and the ammonia concentration was less than 800mg/L,the removal rate of COD and BOD in UASB reactor were 50%and 80%separately,the ammonia concentration had a fall of 50-100mg/L.(4)Under the condition of the DO=1.0-1.2mg/L,the pH = 7.5-8.0 and temperature from 25℃to 30℃,the A/O reactor could keep the state of shortcut-nitrification,the removal rate of COD arrived to about 70%,the removal rate of ammonia and total nitrogen were 85%and 60%,separately.(5) The surface characteristic of anaerobic granule sludge and aerobic sludge were observed by SEM,and then analysed the variety of micro-organism and dominant bacteria.(6) The experimental results chose PFS as the optimal coagulant,under the condition of the dosage of 50mg/L,pH=7-8,the effluent COD concentration decreased to less than 100mg/L;in the Fenton oxidation process,under the condition of pH=5,the dosage of H₂O₂=1mL/L,the dosage of FeSO₄·7H₂O=300mg/L,the reactor time=60min,the effluent COD concentration reduced to 80mg/L,the effluent chroma decreased to 25,the removal rate of COD and decoloration rate arrived to 72%and 90%.