Evaluation of a novel double-layer biological aerated filter (BAF) for drinking water bio-pretreatment: comparison with a single-layer BAF

摘要

Biological pre-treatment for drinking water production is becoming more crucial in developing countries, due to the polluted water resource and stringent water quality regulation. Comparison between a double-layer biological aerated filter (BAF) and a single-layer lava-based BAF had been carried out in terms of organic matter and ammonia removal, and maintenance strategies were discussed. Both the BAFs could achieve satisfactory removal of ammonia, and the former was better to cope with higher ammonia loading due to adsorption ability of clinoptilolite. Dissolved oxygen and pH monitoring demonstrated that desorption would happen when the feed ammonia concentration decreased. The two reactors had similar ability for removal of organic matter; however, the double-layer BAF apparently showed more economically well-controlled considering backwashing during the investigation period. This may be attributed to the special hydraulic flow status, that is, suspended and fluidic flow state in the lower layer, which could decrease the blockage of the light carrier. Moreover, both the BAFs presented a good removal of trace organic matter, such as odor and endocrine disrupting chemicals. Thanks to the superiority of the double-layer BAF, and it could be expected that it has a great potential to act as a bio-pretreatment reply to the problem from polluted source water and stringent water quality regulation.