| Biological filtration technology which combines both biological treatment and solids removal in one reactor has been one of the development directions of wastewater treatment technology. However, its development is limited in our country due to the shortage of the filter media research.In this study, a porous filter media called expanded-perlite was produced, which was cheap and rich in China. Then, the application of the expanded-perlite media was researched. The main conclusions were gained as follows:(1) Roasting is the most important step and the factors influencing the quality of the carrier are roasting temperature and duration. Lower density carrier with coarse and porous surface can be developed under the condition of proper temperature and time.(2) A perlite filter was used to treat the secondary effluent. The filter produced an effluent with an average turbidity of 5 NTU at high filter velocity (16.1m/h). The results demonstrated that perlite media have a good turbidity removal capacity.(3) The biological filter was found to be feasible for the lower concentration domestic wastewater treatment. It can remove the suspended solids at the time of biodegrading organic matters. The experiments showed that the recycling filter performed better under shock loading conditions than the un-recycling filter. And the recycling filter, even lower system of temperature attained stability very quickly, and maintained a higher TCOD-removal efficiencies of 70%.
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