Membrane filters have been applied, in a very limited way, to industrial laundries. The membrane filters that have been employed previously, for the most part, have been misapplied. As a result, the perception is that membrane filters are sensitive and tend to plug easily. When tubular ultrafilters are utilized, they are free from pluggage and can be applied very reliably.

Membrane filters are well-suited for purification of waste water generated by industrial laundries. The membrane filter simply separates clean water from the contaminants mechanically.

Simple Mechanical Process

The membrane filter is a mechanical system that allows clean water to pass the filter. The contaminants are rejected by the membrane filter and returned to the waste holding tank. There are no chemicals required other than that which may be necessary for pH adjustment. Also, there is very little sludge generated by the process. The system simply separates the contaminants from the water, whereas a chemical treatment system generates copious amounts of sludge that must be de-watered and disposed.

Minimal Operator Attention

The process is completely mechanical and is not dependent upon the chemical feed and the coagulation and flocculation process. The only operational requirement is to clean the membrane filters periodically, which is a simple process that involves less than half an hour of an operator's time. A chemical treatment system requires ongoing adjustments of the chemical feed pumps, make-up of the chemical feeds, operation of the de-watering system and control calibration and adjustment. The chemical system tasks require continual attention on a daily basis, whereas the membrane filtration system requires attention only for cleaning.

Consistent High Quality Water

The membrane filter forms a positive barrier to the flow of contaminants and, therefore produces the same high quality water continuously, without operator attention. The membrane system is not affected by the variability of the waste stream. The purified water is suitable for reuse or sewer discharge.

Low Sludge Generation

The mechanical separation produced by the membrane filter does not generate sludge. It simply separates the contaminants from the water and leaves those contaminants in a liquid phase. The amount of liquid concentrate is normally very small and it is, therefore, cost-effective to dispose of that concentrate as a liquid waste and thereby preclude the need to run and operate a solidification and de-watering operation.

Low Operating Cost

The membrane filtration system will be the least expensive treatment system to operate. The cost of operation of a membrane filtration system is 40-60% of a chemical treatment system. A review of the summary of operating costs helps provide an understanding of why the membrane filtration system is so cost-effective to operate.