close
Ultrafiltration
Waste water streams from municipal and industrial sources, as well as natural water are often colored with high turbidity and contain suspended solids and particulate matters. Bacteria and viral agents may also be present, causing the water to be unusable for an application or unacceptable for discharge.
Ultrafiltration (UF) can be used to remove these contaminants. Ultrafiltration is a pressure driven membrane process, with the operating pressure of the system dependendent upon the feed water temperature and filtrate flow. When compared to other membrane processes (such as reverse osmosis), UF systems require a much lower amount of pressure for operation. Typically, an ultrafiltration system will operate between 7 and 45 psi (0.5 and 3 bar).
Ultrafiltration membranes remove colloidal and particulate matter, oils, and grease; while allowing water and some chemicals to pass through. Aside from the concentrate stream (or a backwash water), a minimal wastewater stream is generated from Ultrafiltration. UF systems can typically operate at 90 – 95% recovery, and the reject and/or backwash water is often sent back to the front end of a treatment process for re-treatment.
Significant advancements have been made in Ultrafiltration membrane products over the last decade. These advancements have been driven by technological benefits, the need to reuse wastewater, and stricter regulations regarding the treatment of surface water for use as potable water. Through this developmental stage, no clear technology, membrane type, or configuration has emerged as a leader in the field.
Membranes are available in numerous configurations including hollow fiber, plate and frame, and spiral. The hollow fiber membranes suffer from fiber breakage issues, with thousands and thousands of fibers susceptible to breakage on each and every project. Plate & frame configurations do not have this issue, however they are not as efficient in packaging membrane area and may be cost prohibitive. Both the hollow fiber and the plate & frame have the disadvantage of being proprietary in nature, with the end user locked into the manufacturer for replacements for the life of the product. ENAQUA believes that the spiral UF configuration offers the best combination of membrane technology, simplistic design, cost effectiveness and low O&M costs.
ENAQUA has used spiral UF membranes in applications such as: metal recovery processes, textile wastewater and municipal effluent. In many cases the UF effluent has served as a pretreatment to a downstream RO system, thereby protecting the RO membranes from high level fouling. Since the UF membranes can be cleaned with a very wide range of chemicals, utilizing UF as a pretreatment to RO is often a cost effective and operationally simple treatment scheme.
