Hi Shawn.  Laundry ...

Hi Shawn.  Laundry wastewater requires biological treatment to remove the soluble organic contaminants from the soap and detergent, but biological treatment can be problematic in North Americaas a result of low phosphorus detergent formulations.  As a consequence, if treating laundry wastewater on its own, nutrients generally need to be added to support biological oxidation.  There are a number of ways to approach treatment.  You could consider electro-coagulation or chemical coagulation/flocculation to remove suspended solids and colloidal solids prior to biological treatment, followed by filtration (possibly MF or UF membranes).  Like any industrial wastewater treatment process investigation, pilot testing is highly advisable due to the extreme variability between laundry operations and wastewater characteristics.  RO membranes have also been used, but typically reject around 25% of the wastewater flow to sewer - so water conservation levels are much lower than using more conventional treatment.   The degree of treatment required greatly depends on what level of residual contaminants may interfere with laundry cleaning efficiency.  Biological treatment with ceramic micro or ultra-filtration membranes have also been applied - but the ceramic membranes are still very expensive.