Case Study from HydroFLOW Denmark
Car wash water recycling with biological treatment
Car wash water recycling depends on how well the used water is cleaned, and at a car wash in Denmark the biological system was not cleaning it fully. Dirty wash water runs from an underground pit through a sand trap and biological tanks before it is reused, but samples taken before and after that cycle were both cloudy with suspended material. Two HydroFLOW® i45 units were clamped to the dirty wash-water hoses from the pit, with no chemicals added. The reuse water was markedly clearer after one week and still clearer at week eight, and in a 0.45 µm field filter test the volume passing before the filter blocked rose from 20 ml to 70 ml.
The Challenge
- Car wash water recycling was limited because the treatment cycle did not fully clean the water
- Wash-pit water was turbid and cloudy, with a grey colour
- Even after treatment, the water had a distinct yellow tint and visible cloudiness
- The tint and cloudiness came from suspended particles
- The aim was to improve cleaning so that more water could be reused
The Solution
- Units installed: two HydroFLOW® i45
- Installation point: dirty wash-water hoses after the pit, before the sand trap and sludge pit
- Treatment process: biological treatment, with the clarified water reused in the wash
- Chemicals: none, as the biological system uses no chemical dosing
- Evaluation period: eight weeks, monitoring pit water and cleaned water
To improve car wash water recycling without changing the process, the two i45 units were installed onto the hoses carrying dirty wash water out of the pit. The water was treated before it reached the sand trap and the biological tanks, and no chemicals were added. Pit and cleaned water were sampled over eight weeks, and the reuse water was checked with a 0.45 µm field filter test.
