Pilot investigation of two-stage high speed filtration for the water treatment in Northwest China

In this paper, an innovative two-stage filtration technology that could separately backwash the two filter columns was employed in a drinking water treatment plant, located in Northwest China, Yin-chuan. Effects of filter layer configuration features on the filtration efficiency and head loss were thoroughly studied. Eight types of granular package filter media were investigated and compared to the conventional filtration process. Twelve runs of various filter media and packing height ( of totally 1,000 mm depth) were conducted at a constant filtration rate of 20 m h(-1) using the settled water (1-3 degrees C) from the drinking water treatment plant as raw water. The removal efficiencies for turbidity and UV254 by two-stage high speed filtration technology were similar to those by other conventional filters under the acceptable head loss development. However, the filtration rate of this filter was two times higher than those of other filters while the backwash water rate was only one-third of the conventional filtration technology.