Microfiltration in Wastewater Treatment
Microfiltration in wastewater treatment (MF) process is carried by sending contaminated fluid through a special pore sized polymeric material/membrane to separate microorganisms. MF is a pre-treatment for other separation process. The MF method can filter microorganism such as algae, protozoa Giardia lamblia and Cryptosporidium cysts, algae.
How Microfiltration Works?
“Micro” means small. An MF unit not only removes microbes but also removes particles such as Iron & Manganese solids, clay, silt and sand. MF membrane separation process is based on the presence of semi permeable membranes. Ceramics along with other metals of inorganic materials is used as membranes. Prominently used membranes are made by means of sol/gel process.
Types of Microfiltration:
- Dead-end Micro filtration/Direct Filtration: In direct flow filtration, also known as dead-end filtration, a feed stream is forced through a porous membrane. Particles too large to fit through the membrane pores build up on the filter in a residue known as a filter cake. Dead-end filtration provides more comprehensive filtration of the feed stream, and is typically performed in batch or semi-continuous flows, allowing for the membrane to be replaced or cleaned regularly.
- Cross Micro filtration: also known as tangential filtration, the feed stream flows along the surface of the membrane, producing a purified filtrate, and a concentrated retentive that stays in liquid form, and can be recirculated through the MF process. Crossflow filtration can operate as a continuous process because the constant flow of the feed stream helps to prevent the build-up of solids that block flow through the membrane.