Application of floating medium filter in water and wastewater treatment with contact-flocculation filtration arrangement

Conventional granular filtration, although successfully used in water treatment and tertiary wastewater treatment, suffers from some disadvantages such as limited retention capacity and high energy requirement for backwashing. Use of floating filter medium overcomes these shortcomings especially when direct filters are used in the treatment plants. A laboratory-scale study carried out indicated that the floating medium filter with downflow direct filter arrangement was a good pretreatment unit to reduce the pollutant load in rapid filters used as polishing filter units. Due to its ability to form uniform micro-flocs of the order of 26–40 μm throughout the filter run, the floating medium filter can serve as an excellent static flocculator.