Ultrafiltration and reverse osmosis work together

Ultrafiltration (UF) and reverse osmosis (RO) are essential components of wastewater reuse and desalination applications and were a key part of an emergency bulk water plant for Ndlambe Municipality.

Quality Filtration Systems (QFS) recently designed, engineered, manufactured, installed and commissioned the 5 Mℓ/day plant, comprising 3 Mℓ/day wastewater reuse section and a 2 Mℓ/day desalination section.

Located next to the Port Alfred wastewater plant, the emergency bulk water plant has created 43 new job opportunities.

Both parts of the plant employ a UF process, followed by RO. “The UF provides the best pretreatment to RO, as well as other process water treatment equipment,” says Herman Smit, managing director of QFS.

UF targets the suspended solids in the feedwater, resulting in nephelometric turbidity unit (NTU) levels of less than 0.1. In RO terms, UF provides feedwater to the RO at silt density index levels of less than 1.

The removal of the suspended solids enables the

RO to do the work of dissolved solids removal with less biofouling and sludge blockage in the spacers. Additionally, UF keeps the RO membranes clean, thus increasing the RO membrane lifespan while also reducing client maintenance and operating costs.

Herman Smit, managing director of QFS

Desalination

Desalination is used widely around the world, taking the salt out of water to make it drinkable. Desalination not only eliminates salt from water, but also eliminates potentially hazardous minerals and compounds. Microorganisms are removed by physically getting filtered out by the UF membrane, which has a pore size of 0.04 microns.

The infographic below shows how the 2 Mℓ/day desalination plant works.