Iron Filtration For Chilled Water Loop
Recently a customer contacted Complete Water Solutions after experiencing high levels of iron in the chilled water loop. Iron is a major makeup of the earth’s crust. Iron occurs naturally both in groundwater and surface waters. Waters containing iron are not known to cause any harmful effects in humans. Iron does interfere with many operations, staining on plumbing fixtures, causes difficult situations in distribution systems by supporting the growth of iron bacteria. The customer had testing performed by their chemical vendor noticed increased iron levels ranging upwards of 40 PPM. The high iron levels were causing massive issues when it came to the heat exchanger. The customer had multiple cartridge filtration points throughout the entire loop and before each heat exchanger. After the chilled water made it past the cartridge filtration points, it still caused issues in scaling up the heat exchangers. This was due to the heat, which caused the iron to deposit on the surface of the heat exchanger, causing iron scale. This iron scale caused machines to overheat and shut down the production line.
Why Didn’t The Filters Catch The Iron?
The main reason the cartridge filters did not catch the iron is that the iron was in ferrous form. Simply put the iron was not a floating particle that could be trapped in the cartridge filter. In order for iron to go from ferrous (non-particle/dissolved) to ferric (a particle) there needs to be an oxidizer. Some common oxidizers are air, chlorine, ozone to name a few.
What did solve the problem?
Complete Water Solutions provided a greensand iron filtration system. The greensand media is a black filter media used for removing soluble iron, manganese, hydrogen sulfide, arsenic and radium from groundwater supplies. The manganese dioxide coated surface of GreensandPlus acts as a catalyst in the oxidation-reduction reaction of iron and manganese. The greensand filter was installed in a side stream option. The greensand filter when regenerating used city water so that the chemically treated chilled water would not be wasted.
The greensand filter in combination with bleeding the system in small amounts over time brought the system down from 40 ppm to under 4 ppm within a short amount of time.
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