Nonpotable Reuse: Development of Health Criteria and Technologies for Shower Water Recycle

The U.S. Army is evaluating recycle of field shower water as a conservation practice in arid regions and is seeking to define appropriate technologies and health criteria. Shower wastewaters at a military installation have been characterized in terms of physical, chemical and microbiological parameters. Two treatment technologies have been investigated. Microfiltration cartridges with a nominal pore size of 0.2 µm achieved consistent removals of 75±15% of total organic carbon (TOC) and better than 99% of turbidity from synthetic shower water containing 50 to 100 mg/L of TOC as soap. An alternative treatment technology utilized powdered activated carbon and coagulation/flocculation/sedimentation followed by diatomaceous earth filtration. A TOC reduction of 70±15% was achieved in three separate studies, although at a cost of 1 g/L or more of powdered activated carbon. Revised quality criteria for recycled shower water have been developed with guidance from the National Research Council. Parameters which can practically be measured in the field are primarily associated with microbiological safety. Therefore, the safety of recycled shower water with respect to chemical contamination must depend on design considerations.