There are two common types of filtration methodology normally used in wastewater treatment system to separate out the sludge from the wastewater which are either clarifying type or the normal cake filtration type. The clarifying types mostly involve the use of filter bags or cartridges (up to 10 micron) which are meant to get crystal clear discharge water. It is a highly preferred method when there is only a small amount of discharge wastewater expected per day (usually less than 20cubic meters) and also in industries located in critical places such forest catchments area whereby there’s a strict regulation that allows only high quality of treated wastewater to be released to the environment.
On the other hand for the solid cake filter, whereby it offers a rather crude method to separate out the sludge, it is more often employed in wastewater plants since it offers a higher treatment capacity with much lower cost. One of the common equipment built around the solid cake method is the Plate and Frame Filter Press whereby it is made up of a series of plate compressed together using hydraulic force and using a pump to force the wastewater through the configuration. The filter plates are usually lined with filter cloth combined with a thin layer of filter paper which acts as a filtering media and once the filter plates are choked up with solids, the formed cakes can be easily removed by opening the pressurized system.
Use of the plate and frame filter press is widely preferred in today’s wastewater system not only because it is easy to use and operate but it also offers a clean and effective method to produce wastewater discharge meeting standard regulatory controls. Recent development to enhance the use of plate and frame type has led to better design of low-weight filter plates (which reduces downtime incurred during cake discharging process) and advanced systems are also built to accommodate higher feed and filter cake retention capacity.
Apart from that, the development on filter cloth technology is also very important because the sealing properties are one of the main considerations for the filter system to be fully functional. Further progress has seen design of synthetic cloth types to replace the conventional monofilament and polyfilament cloths.
Other dewatering methods and use of Belt Filter Press