Removing Soluble Iron from Closed Loops: A Case Study of Using the Strengite Process to Remove Soluble and Total Iron from a Live Chilled Water Systems
It is not unusual for closed loop systems to become fouled with excessive soluble and insoluble iron and copper. This can be caused by system deteriation, changes to the systems, or bacteria infection. All negatively effect the system operation and increase the energy to run the system. The standard solution is to flush the system out with fresh water until the water is clear of soluble and insoluble metals. This means losing all the chemical treatment within the system. Typically it will require a water supply and drainage capable of replacing the system volume ten times over. This is both wastes clean fresh water and creates water pollution. Closed loop flushing is considered to be the largest source of heavy metals such as copper, lead, and zinc to the sewage system. In many areas, the discharge will require a discharge permit.
A Chilled Circuit with Excessive Iron Levels
Heckfield Place in Bothey Spa, Hampshire had a chilled water circuit that was fouled with excessive levels of soluble and total iron. The site needed to clean this system, but lacked a water supply and drainage that could be used to flush the circuit. The chilled water system had a volume of 2000 litres. Iron levels were 100 ppm total iron and 41 ppm soluble iron. Copper levels were 0.6 ppm total copper and 0.3 soluble copper. The site did not want to undertake a clean of the metal surfaces within the chilled water system.
Left bottle was the starting sample. Middle sample was taken during the cleaning, and the right bottle was the final sample.
Removing Soluble Metals without Discharge
The Strengite Process was used to clean up the water within the chilled water systems without discharge and without taking the systems off line. This was achieve by operating the Strengite Process so that approximately four to six system volumes were passed through the Strengite equipment. The Strengite Process caused the soluble iron and copper to come out of solution so that they could be removed on filter bags.
After operating the Strengite Process on the system water, the chilled water system had final iron levels of 0.8 ppm total iron and < 0.2 ppm soluble iron. Copper levels were < 0.2 ppm (the limit of detection). No water was lost during the cleaning. The system remained in operation throughout the cleaning. The use of the Strengite Process for cleaning up the chilled water system avoided consuming and polluting approximately 20,000 litres of water.
The Strengite Process does not impact closed loop corrosion inhibitors such as nitrite and molybdate. The system water at Heckfield had a molybdate level of 20 ppm at the start of the process. It was unchanged at 20 ppm at the end of the cleaning.
The Strengite Process offers a more sustainable way to remove excessive iron and copper from closed loop systems.
Soluble metals become insoluble and are removed on filter bags.
The Strengite Process is a patented process. The technology, equipment and products for the Strengite Process are only available to licenced and trained water treatment specialists who operate to a high standard and skill level.
Strengite equipment used to clean the system.