Application of Granular Media Filters

Granular Media Filters for wastewater treatment plant is basically designed with special considerations put in mind for certain needs such as having the requirement to deal with larger particle size from suspended solids and higher demand load which may considerable affect performance. Unlike those made for treatment of potable water in household usage, special changes were needed to cope with wastewater feeding at higher flowrates while design of the filter bed must be able to deal with variable factors such as impaction of particles that adhere to the filter media and growth of biological solids within the bed.

Filtration of wastewater should be applied after undergoing secondary treatment before discharging to general monsoon drain. Basically, it is needed to remove residual precipitates generated from metal salt which were used earlier during phosphate removal in chemical precipitation and it is important that the level must be lowered down before final release. Generally if properly treated, the filtered water may even be considered to use for food crop farming irrigation.

Design of a granular media filter will very much depend on several factors whereby incoming plant flowrates will determine the surface area of the filter bed. This will affect the size and number of required filter units required and generally the less, the better because cost is another factor that you need to control as well. A good design approach must be that if a filter unit becomes unavailable because of opening for backwashing and servicing, other remaining units must be able to cope with the incoming wastewater without jeopardizing filtration performance. Therefore the combined capacity of all the filters are usually 1.5 times higher than the total load that the whole system was made to handle. Next related topic, different types of granular media filter in wastewater application and the role of intermittent sand filter.

Recommended Engineering Books