Hybrid filtration method for pre-treatment of stormwater

摘要

In this study the hybrid filtration process (combining fibre filter with deep bed dual medianfiltration) was investigated as pre-treatment to stormwater. This process was investigatednin-terms of reduction in turbidity, dissolved organic carbon (DOC), colour, headloss developmentnacross the filters, suspended solids removal, organic matter removal, nutrients and heavy mattern(such as iron, copper, lead, zinc) removal efficiency. A comparison was made between the hybridnfilter with single media (sand) deep bed filter and fibre filter. It was found that the hybrid filtrationnsystem successfully removed turbidity (98%), colour (99%), suspended solids (99%), and DOCn(55%). The removal efficiency of heavy metal was relatively low as the concentration of heavynmetals present in stormwater was low. The removal efficiency of nitrate, nitrite and phosphorousn(as orthophosphate) was 27, 35 and 72% respectively. Hybrid filtration processes showed a betternreduction of Modified Fouling Index (MFI) value (from 15.500 s/ln2nto 9 s/ln2n) compared with singlenmedia sand, anthracite and fibre filter which were 35 s/ln2n, 13 s/ln2nand 14 s/ln2nrespectively whennoperated at FeCl3 dose of 15mg/l.