Wastewater Treatment Plants

To understand the concentration of consumer product ingredients in the environment, we have to understand wastewater treatment plants. Typically, the wastewater from a home goes into some type of wastewater treatment plant. These plants can be large wastewater treatment plants which treat the waste of many people in a town or city, or they can be small on-site septic systems which treat the waste from only one or a few homes.

Wastewater treatment plants take in wastewater, treat it and produce a liquid effluent containing primarily water and a solid material called sludge . Effluents are usually released to surface waters like rivers and the oceans, and sludge is disposed of in landfills, incinerators or is used by farmers as a fertilizer. Due to the treatment processes that occur in the sewer and during waste treatment, the concentration of consumer product ingredients used in the home is greatly reduced by the time effluent reaches surface waters or sludge reaches soils.

The four major treatment processes in a wastewater treatment plant are biodegradation, volatilisation, sorption, and dilution. These fate processes start in the sewers and continue in the wastewater treatment plant. The result of these processes is that the concentration of consumer product ingredients is well below the concentration that will affect the environment.