Study On Landfill Leachate Degradation Behavior In Aerobic MBR Process

Landfill leachate, discharged from the landfill disposal, is one type of organic wastewater with high concentration load. Due to its quite variable in quantity and quality, high ammonia concentrations and high toxicity to micro-organisms, it is hardly difficult to be treated by traditional biological treatment processes. Although the management of city environment is strengthened increasingly by government, the more sanitation landfills and leachate have been created continuously every year, which will further cause the severe environmental problems. The membrane bioreactor (MBR), a combined process of biological treatment with advanced membrane separation, is a new technique for wastewater treatment. It is an effective process specially to be employed in high concentration and slow-biodegradable wastewater treatment.In this work, the removal behaviors of COD and NH4+-N in landfill leachate treatment were investigated by using aerobic membrane bio-reactor(O-MBR) process. The optimal operational parameters were obtained based on the removal behaviors of COD and NH4+-N under various pH value, C/N and concentration loads in the influent as well as HRT. The relationships between the each effect factors and biodegrading behaviors of sludge in this system were revealed. The results were summarized as follows:(1) pH value is one of the important factors for nitrification in MBR, at nitrification's optimal pH 8.0,the average removal efficiency of NH4+-N were 88%,80% above of the NH4+-N was converted to nitrate.(2) C/N ratio appeared the less important factor for NH4+-N and COD removal in aerobic membrane bioreactor. When influent NH4+-N and COD were 200mg/L～300mg/L and 1000mg/L～1800mg/L,HRT was 2 days, the removal efficiencies of COD, NH4+-N and TN reached possibly at about 80%～90%,75%～80%and 10%～20%, respectively.(3) When the influent concentration loading was less than the maximum sludge loading in our system, the removal efficiency of COD and NH4+-N could be remained at a high level. However, when the influent content loading was larger than the maximum sludge loading, removal efficiency of COD and NH4+-N dropped with the increase in influent content loading in which the inter-inhibition relations between the nitrifying bacteria and organic-utilizing bacteria occurred easily at relatively higher COD and NH4+-N concentration.(4) The optimal HRT observed in my experiment was one day.(5) Membrane fouling occurred more easily with the increase in influent concentration load and the shorter HRT, small membrane flux is required to prolong the membrane life and limit the membrane fouling. Membrane flux was able to be recovered by about 92.7% after cleaning treatment by alkaline and acid.