Experimental Study On Wastewater Treatment Of Service Area In Expressway By Membrane Bioreactor (MBR)

Presently, the service area in expressway in our country has achieved rapid development,and the service area has provided convenience for drivers and passengers, which also produced acertain amount of wastewater, so how to deal with the sewage of the service area has become animportant issue before us. To solve these problems, hollow-fibre membrane was made intoMembrane Bioreactor （MBR） to treat the simulated wastewater in this thesis, aimed at providingtechnical support for sewage treatment of highway service area. The main contents andconclusions are as follows:（1） Study has been conducted to evaluate the effect of aeration rate, HRT, pH and time ratioof aeration:mixing （or system backwash ratio） on MBR removing organic matters、ammonianitrogen、total nitrogen and total phosphorus from wastewater of highway service area, and theoptimal parameters for stability of the system were identified. The test results showed that whenaeration rate=1000L/h, HRT=8h, time ratio of aeration:mixing=2h:1h, and pH=7.5, the averageremoval efficiency of COD、NH₄⁺-N、TN and TP in IAMBR was97.71%、69.96%、63.32%、95.48%respectively, and the effluent can be used for urban greening and construction; Whenaeration rate=1200L/h, HRT=10h, pH=7.5, and system backwash ratio=300%, the averageremoval efficiency of COD、NH₄⁺-N、TN and TP in A/O-MBR was98.52%、82.68%、72.16%、97.30%respectively, and the effluent satisfied urban miscellaneous water quality standards andcan be used for flushing, road sweeping, fire-fighting, greening or vehicle washing.（2） Sludge characteristics and methods of membrane cleaning have also been researched.Sludge in MBR has stable concentration of6000⁷000mg/L and high activity. Besides,membrane fouling can be controlled within a certain range, and membrane flux can get a betterrecovery after cleaning. A/O-MBR were better able to fight against membrane fouling.（3） Dynamics model of MBR removing organic matter has also been established, which canbe used to predict the contaminants`concentrations.（4） Furthermore, a preliminary analysis has been conducted to verify the economicalefficiency of membrane bioreactor used for removal of highway service area sewage.Infrastructure investment of MBR used for treatment and reuse of service area sewage is similarwith the investment of normal biological treatment, while operating cost of MBR is lower thanthe cost of normal biological treatment, so it is economically viable.MBR could solve the problems that existed in the highway service area wastewatertreatment effectively, with high-quality effluent, stable and reliable operation, high degree ofautomation, and lower operating costs. Effluent reuse can produce good economic andenvironmental benefits, so this method has a wide application foreground.