What does wastewater from commercial laundries contain?
Fats, oils and greases (FOG) as well as total suspended solids (TSS), are the major impurities of concern. These impurities are derived from the soils which are removed from clothing as well as from the chemicals which are used. Laundry wastewater may also carry additional impurities, but for the purpose of this article we will address FOG and TSS, the most common contaminants. Why are high levels of FOG so undesirable? FOG and other organic chemicals are digested, to produce carbon dioxide and water, by sewage bacteria which feed upon them. In this process, these bacteria consume and deplete the dissolved oxygen in the water. If untreated wastewater were to be discharged directly into rivers and streams, it would also deplete the dissolved oxygen and put marine and plant life risk. A measure of organic water quality contamination is its Biological Oxygen Demand or BOD5 . This is a measure of the amount of oxygen wastewater consumes over 5 days, at 20oC during the biological break down
