Removal of sediment and other suspended particles is critical to the efficient, cost effective operation of any membrane treatment system. Performed using depth filtration media, the initial particle trap filters and system prefilters preserve RO membrane performance and can reduce the frequency of RO membrane cleaning.
Treated process water often passes through tanks containing activated carbon powder that may release small particles. Softeners and deionization tanks contain resin beads that may break down, fracture and release small particles. In both cases, filters are used to trap the particles and prevent their contamination of downstream treatment process steps. Again, depth filtration is most often used for this function.
Chlorine must be removed from water entering most RO systems, so there is no protection against the growth of organisms that may become trapped in the RO system. Those organisms can grow and be released downstream to contaminate a distribution system and/or medical devices and treatments. To protect the downstream systems, and prevent possible pathogens from reaching patients, filters are used to reduce and remove bacteria.
Filters help prevent contamination of purified water in the storage tank, protecting both the system and patients. The air around tanks is full of airborne bacteria, other organic contaminants and particulates. Drawing water from a tank also draws that contaminated air into the tank.
Very few healthcare facilities have water systems in controlled spaces similar to cleanrooms. The tanks used for water storage are also not sealed but have a loosely attached covered opening for inspection and cleaning. Securely closing the cleaning hatch and adding particulate filtration for air may keep dust out of the system.
Some facilities may want to protect the water system from airborne bacteria. Installing a hydrophobic membrane filter will protect tanks from bacteria and small particles and protect patients.
Filtration in Medical Water System Distribution Loops
The schematic above shows the RO/DI water treatment system feeding water to a tank that is the beginning and end of a recirculation/ distribution loop. Some systems are designed to feed water directly from the RO/DI unit to an end use without a tank or distribution loop. Other systems can use potable water that has been filtered but not treated by RO or DI. Below are details of the common configurations of filters used to remove bacteria from a loop system or from a direct feed of treated or potable water.
Option A splits the flow to allow filters to be changed without having to shut down a continuously recirculating loop system. Not shown is the valve system that will direct all flow to either the upper or lower half of the filter group. Two filters are used. The first removes the majority of bacteria and other organisms, the so-called bioburden reduction filters. Removing the bulk of the contaminants protects the critical bacteria filters from being overloaded if there is a system upset.
Option B is a single branch system with the same sequence of bioburden reduction filter followed by bacteria removal filter. If potable water is used, then a particle filter is recommended to capture larger particles and protect the bioburden reduction membrane filter. Filter changes are done by shutting valves that prevent flow through the filters, replacing the filter elements and opening the valves to resume filter operation. Any downstream systems will need to be shut down during the filter replacement process.
Filters for Water Distribution Loops
Option A - Continuous Distribution Loop
Option B - Direct Feed System
Safety at Any Flow
With configurations ranging from 13mm disc filters to 40" cartridge filters, all made with the same attention to quality and cost, Critical Process Filtration has filter products to fit flows from a few milliliters to thousands of gallons per minute. Whether using a filter for small scale lab research, for removing bacteria as part of a large water system, or filtering an instrument disinfectant, Critical Process Filtration will deliver a cost effective filter solution.
Contact Critical Process Filtration for more information.