Process Water

Where are filters used within process water?

Raw Water

Raw water is likely to contain a diverse range of organic and inorganic material. Removal of the particulate contaminants is important to ensure the effectiveness and life of the resin beds used in water Softening. Bags or depth filters rated between 10-100 microns are the typical selections for raw water filtration and the exact choice is dependent on the water at the site. Industrial housings are the best choice in these applications.

Chlorine Removal from mains water

Typical towns mains water will contain an elevated level of chlorine and other organic contamination which will need removing to protect downstream systems such as RO/UF membranes. Cartridge carbon filters offer an efficient and cost-effective method for removing chlorine from water. Like raw water applications industrial housings are chosen.

RO/UF Membrane Protection

Pleated depth filters are used to prevent fouling of RO and UF membrane systems by fine particulates and organic material. Manufacturers of membrane products will set a specification for feed water quality and pleated depth filters with a 5 or10 micron rating help ensure the water meets the required specification. For higher flow systems over 150 m3/hr then the high flow format of cartridges is used. Dependent on the specification or use of the water the full range of housings might be used (industrial, hygienic, sanitary, or high flow).

Wastewater

To meet the necessary disposal or recycle requirements wastewater often requires filtration prior to disposal. The level of filtration required will be determined by local authorities, but either bag or depth filters can be used and normally are installed in industrial housings.

Pre and Post Ultraviolet Treatment

To ensure effective control of bioburden, UV units rely on filtration of the feed water to remove particulates that will produce ’shadowing’ and regions where full UV penetration is not achieved. This will reduce the efficiency of the UV treatment. Typically, pleated depth filters are used for this application and in the high flow format for larger flowrates and these are fitted into hygienic or sanitary housings because systems can be subject to CIP.

POU Filtration

Filters are installed at POU to guarantee the absence of microorganisms or particulate. The distribution system is typically a ring that the water recirculates around. Filters are attached to take off points on the ring or located at the inlet to the equipment the purified water system is feeding. PES membranes are used for this application either in cartridge format, if filtration is done centrally, or if a point of use a choice can be made between cartridge or capsule format dependent on flow rate required. Housings in this application can be plastic or more usually of a hygienic or sanitary st.st. design.

Vent filters for storage tanks

To maintain the quality of stored water during filling, emptying and storage in storage tanks used to balance system flows the use of vent filters is recommended. This prevents air being drawn into the tanks, as they empty, causing recontamination of the water from air borne bacteria. PTFE membrane filters are used and are either supplied in a capsule or cartridge format dependent on size required. Capsule filters are directly fitted to the tank; however, a cartridge will require a st.st vent housing. Where the tank operates in a hot water system or for WFI storage then cartridge filter and housing are used, as the filter must be heated to prevent wetting of the filter by condensation ensuring uninterrupted operation.

Ion exchange Trap Filters

Water softening, deionising, polishing mixed bed and EDI systems all use resin- based technology. They rely on effective filtration upstream and downstream. Prefiltration, either bag or depth filters, is required to protect the resin beds from particulates that could reduce efficiency and life. Pleated depth filters are used as ‘traps’ on the effluent to capture any shed resin that will contaminate downstream plant. Bag or depth filters rated at 5 - 10 micron is used upstream as often the particulate may be high and the range of particulates unknow. On the downstream side 1 - 5-micron pleated depth filters because the loadings are far lower, and the particle range known. Because this is at an early stage of the water treatment plant industrial housings are chosen.