Process and Water High Purity Water Systems contain three core groups of equipment. These groups of equipment are typically categorized as pretreatment, primary purification and distribution systems.
The three major water treatment components of standard pretreatment systems used in Process and Water High Purity Water Systems are sediment filters, activated carbon filters and water softeners.
Sediment filters remove dirt, suspended solids and other particulates and generally lowers the turbidity of the feedwater supplied to the high purity water system.
Sediment filters in most small high purity water systems are standard cartridge filter housings with 5-micron cartridge filters. Most medium to large systems utilize multi-media backwashing filters.
Activated Carbon Filters
Activated carbon filters remove chlorine and reduce organic contaminants. The removal of chlorine protects the reverse osmosis (RO) membranes and ion exchange (IX) resins downstream in the high purity water system. The reduction of organic contaminants contributes to lower total organic carbon (TOC) levels in the water produced by high purity water systems.
The activated carbon filters in most small high purity water systems are standard cartridge filter housings with granular activated carbon (GAC) cartridge filters or carbon block cartridge filters. Most medium to large systems utilize exchange tanks filled with activated carbon or backwashing filters filled with activated carbon.
Water softeners remove minerals and other scale forming ions along with dissolved metals like iron and manganese. The removal of minerals and metals prevents fouling and scale formation on the RO membranes, resulting in maximum RO membrane life.
Water softeners of appropriate size are generally used in high purity water systems. As an alternative, anti-scalant chemicals can be fed into the feedwater using metering pumps. These chemicals keep the potential scale forming ions in solution, limiting scale formation and build-up on the RO membranes.
Primary Purification System
Process and Water High Purity Water Systems typically use reverse osmosis water systems for primary purification. A carbon trap filter precedes the RO membranes.
Reverse osmosis water systems consist of a high-pressure pump and motor, RO housings and RO membranes. The pump and motor provide the pressure necessary for the natural osmosis process to be reversed. The RO housings hold the RO membranes and provides concentrate and permeate flow paths or streams. The RO membrane elements provide the semi-permeable membrane that allows the reverse osmosis process to happen. The pressurized feedwater is forced through or permeates the semi-permeable membrane leaving the contaminants contained in the feedwater behind as concentrate in the waste stream. In addition to sending the contaminants to drain, the concentrate or waste stream provides a constant flow across the membrane surface minimizing the build-up of contaminants on the RO membrane surface.
Conductivity Probes are standard equipment on all Process and Water Reverse Osmosis Water Systems. Many system manufacturers consider conductivity probes optional equipment.
The carbon trap filter is a preventive measure used to remove any chlorine that is not removed by the primary carbon filter in the pretreatment system and to remove any resin or media that may inadvertently pass from the multi-media filter, carbon filter or water softener.
Distribution systems used in Process and Water High Purity Water Systems generally include high purity, cone bottom atmospheric storage tanks with 0.2-micron vent filters and pressure transducer level controls, re-pressurization pumps, mixed-bed deionization (DI) vessels with cation and anion IX resin, ultraviolet light (UV) systems and post or final polishing filter housings with absolute rated 0.2-micron cartridge filters.
Atmospheric Storage Tank
The atmospheric storage tanks are used in high purity water systems to collect and store the RO permeate or product water for future use.
The 0.2-micron vent filter prevents contaminants from entering the storage tank when water is removed from the tank and air replaces the water. The level controls turn the RO water system on and off based on the amount of water contained in the storage tank.
Mixed-Bed DI Vessels
Mixed-bed DI vessels are used in high purity water systems to further polish the RO permeate, reducing the total dissolved solid (TDS) levels.
The cation resin is “pre-charged” with positively charged hydrogen ions (H⁺) and exchanges the hydrogen ions for other positively charged ions (eg. Na⁺, K⁺, etc.) in the RO permeate and the anion resin is “pre-charged” with negatively charged hydroxide ions (OH⁻) and exchanges the hydroxide ions for other negatively charged ions (eg. Cl⁻, SO4⁻, etc.) in the RO permeate. The hydrogen ions and hydroxide ions combine to form pure DI water (H⁺+OH⁻=H2O).
The cation resins are regenerated with sulfuric acid or hydrochloric acid and the anion resins are regenerated with sodium hydroxide.
Ultraviolet light systems are used in high purity water systems to inactivate bacteria and other micro-organisms, preventing them from reproducing.
This reduces the bacteria load in the RO permeate and minimizes bio-film build-up in the storage tank and system piping.
0.2-Micron Polishing Filter
Final polishing filters are used in high purity water systems to remove any sub-micron contaminants still in the DI water, along with any particulate matter picked up by unused DI water returned to the storage tank after flowing through the distribution piping.
Additional or Optional Equipment Used in High Purity Water Systems
Process and Water High Purity Water Systems may contain additional equipment to meet higher water quality requirements or optional equipment requested or preferred by the end-user.
Ultrafiltration systems may be used in high purity water systems in place of traditional pretreatment systems when better pretreatment is desired, higher water recoveries are required or when the system is supplied with challenging feedwater.
These systems can also be used as the primary purification system, replacing the RO and DI components, when lower water quality is acceptable and higher water recoveries are required or desired.
Electro-Deionization (EDI) Systems
EDI systems may be used to replace mixed-bed DI vessels on purified water systems or in conjunction with mixed-bed DI vessels on ultrapure water (UPW) systems.
These systems can be used to reduce operational costs, reduce labor costs and save space.
Ozone systems are used on sanitary systems where bacteria levels must be kept to a minimum.
TOC Reducing UV Systems
TOC Reducing UV Systems are used as ozone destruct units in sanitary systems, to further reduce bacteria levels and prevent bio-film build-up for longer durations in non-sanitary systems or where very low TOC levels are required.
Heat exchangers lower operational costs in sanitary systems and high-temperature systems.
Process and Water offers high quality control panels and instrumentation in the system packages.
Process and Water High Purity Water Systems are available in a variety of piping materials to meet the requirements of most high purity water specifications. They are skid-mounted and come complete with interconnecting piping for ease of installation, while reducing installation time and costs