Anodizing's environmental friendliness and relative safety are among its best properties, in the age of increasing concern for human protection and quality of our land, water and air.
Anodizing uses simple water-based chemicals that can be treated easily and that release no harmful by-products. The liquid by-products are recycled and returned to the process. Solid by-products can be isolated and diverted for use in the manufacture of alum, baking powder, cosmetics, newsprint, fertilizer and water purification systems. The U.S. Environmental Protection Agency, which heavily regulates the production and use of solvent-based paints and flour polymer finishes containing volatile organic compounds (VOCs), regards anodizing as an environmentally friendly process.
Anodizing does create a by-product composed primarily of aluminium hydroxide, some aluminium sulfate and water. It is harmless because it contains no significant amounts of heavy metals. In some cases, municipal sewerage treatment plants benefit from these by-products by using them as filters in the secondary treatment of sewage.