What are environmental issues are involved with aqueous cleaning?
Generally, the environmental issues involved in aqueous cleaning have to do with the ingredients used and their ultimate discharge into the environment. Taking a larger view, it is also important to consider the energy and resources consumed in making and using the cleaner.
There are several important factors concerning discharge of spent cleaning solutions into the environment: biodegradability, aquatic toxicity and eutrophication acceleration. Early detergent formulations contained poorly biodegradable surfactants
that often caused foaming of lake and river surfaces after spent solutions were discharged to drain. All modern detergent formulations use biodegradable surfactants that do no buildup or persist in the environment causing foaming problems.
Aquatic toxicity can come from very high or very low pH or from toxic ingredients. Where extreme pH cleaning is required, it is advisable to neutralize or discharge spent solutions in small enough quantities to avoid problems. The surfactants in aqueous cleaners may be a source of aquatic toxicity. The use of biodegradable surfactants and the discharge of limited quantities of cleaning solutions generally results in safe concentrations of surfactants on water surfaces. Older, more highly toxic surfactants are rarely used in aqueous cleaner formulations.
Eutrophication involves cleaners that contain phosphates. Phosphorus is an essential nutrient for algae. When significant amounts of phosphorus are discharged into surface water, vigorous algae blooms may result. The algae die and settle to the bottom filling lakes and ponds with silt and organic matter more rapidly that normal. Although eutrophication is a normal, natural process, the acceleration of this process by phosphates is undesirable. The main source of phosphorous in surface waters is agricultural run-off from farming. There are no national regulations restricting the use of phosphates in cleaners, however, many states and municipalities have enacted legislation that restricts the use of phosphates in household cleaners. There are currently no restrictions on the use of phosphate containing cleaners in industrial cleaning applications.