Experimental Study On Wastewater Treatment Of Service Areas In Expressway By Biological Aerated Filter (BAF)

Presently, with the development of the service areas in expressway in our country, the problems that are consisting in the wastewater treatment of service areas have arisen increasingly. Some achievements have been obtained by the traditional methods in a part of service areas, however, Some problems have still been existed. In view of the problems, the text tried to treat the wastewater from service areas by fly ash filter Biological Aerated Filter(BAF) in order to find a new method to treat the wastewater from service areas.Further study has been conducted to evaluate the performance of fly ash filter BAF removing organic matters,ammonia nitrogen,total phosphorus,suspended substance etc from wastewater of service areas. Furthermore, several factors considered affecting BAF process have been examined which are gas to liquid ratio,hydraulic loads,the height of filter,contaminants` loads and backwash of BAF. Moreover, the dynamics models on how the organic material and ammonia-nitrogen were degraded were achieved. The test results showed that the performance of the fly ash filter BAF to treat the wastewater of service areas was excellent, which could remove the organic matters,ammonia nitrogen,total phosphorus,suspended substance etc effectively; In the condition that the gas to liquid ratio was 10:1, hydraulic load was 1.01～1.53 m3/(m2.h), water temperature was 13.6～26.7℃, the average removal efficiency of CODcr,NH3-N,TP,SS was 77.93%,84.70%,77.54%,58.90% respectively, also the effluent could be satisfied. Appropriate gas to liquid ratio is 10:1; hydraulic load has little influence on the effect of the BAF when it varied in a certain range, but if hydraulic load exceed the certain range, with the increasing of the hydraulic loads, the average removal efficiency of the contaminants ware decreasing; The increase of the media height of the BAF can improve the removal effect of BAF; When the contaminants` loads were varied in a certain range , the BAF had a strong resistance to the impacts of the contaminants` impulse; Backwash had less impact on the removal effect of BAF, which could return to the pre-wash level in a short time after backwash; The dynamics models curved could predict the contaminants` concentrations.Fly ash filter BAF could solve the problems that consisted in the wastewater treatment, effectively. Some of the device`s running parameters founded by the experiment had a instruction function on the design and application; Fly ash filter BAF biologic technology treating polluted water has such characteristics as small volume, high dimension load, high treatment efficiency and effluent water quality, low investment and running cost etc, so its application prospect is very wide.