Direct filtration is defined as the treatment system in which filtration is not preceeded by sedimentation.
The direct filtration processes differ from conventional sedimentation-filtration systems in that the total solids must be stored in a filter.
The chief advantage of direct filtration is the potential for capital cost savings up to 30 percent under favorable conditions, compared with conventional treatment processes.
The feasibility of using direct filtration to treat biological treatment effluent (secondary effluent) of waste water was investigated by pilot plant tests.
The important design variables of the filter such as size and thickness of media, media type, filtration rate, backwash system was investigated by applying design equations and pilot plant tests.
Activated carbon was used to remove organics dissolved in water.
During the tests, the raw water was prepared to have turbity 30 Ntu and the influent of the activated carbon column was prepared to have COD 30 ppm.
Direct filtration produced finished water turbidities from 0.1 to 0.5 Ntu, well below the Korea drinking water standard of 2 Ntu and activated carbon adsorption produced finished water COD below 10 ppm.
