Abstract:

In order to avoid the micro-pollution of drinking water source due to ammonia nitrogen ( NH₃-N) and organics,for the first time,a waterworks in Guangzhou city adopted the high-rate up-flow biological aerated filter ( HUBAF) with a flow rate of 735 thousand ton per day as a pretreatment process. In the first three months after the stable operation,the NH₃-N content and CODMn in raw water respectively reached 0.44~2.22 mg /L and 1.84 ~6.06 mg /L,and those in the pretreatment effluent were respectively below 0.5mg /L and 2.0mg /L. Moreover,the iron and manganese contents in the raw water were respectively up to 1.16 and 0.22mg /L,while those in the waterworks effluent were respectively 0.05 and 0.03 mg /L. Due to the large-particle ceramic filter media combined with fluid-bed technology,the average removal of turbidity was only about 2.5 NTU and the head loss was steadily below 1.0m. HUBAF adopts an air-water-combined backwashing system with up-and-down flow,which keeps the change of head loss within 0.1m and makes it possible to share a common aeration system in the filter. The application of HUBAF demonstrates that,as compared with the biological pretreatment technologies that have been put into application,such as the elastic packing-contact oxidation technology and the suspended-ball fluidized technology,HUBAF possesses stronger resistance to impact loading,higher NH₃-N nitration rate and better removal of iron and manganese,and that the“HUBAF-conventional treatment”combined system is of a organics removal similar to that of the“O₃-BAC”advanced process.

Key words: water treatment, micro-polluted water source, biological pretreatment, high-rate up-flow biological aerated filter, head loss, backwashing manner