The USEPA has established water quality criteria for aluminum. Many US States have adopted these criteria and require dischargers to meet water quality standards placed in their discharge permit. No direct relationship between dissolved Al and toxicity was shown for a wide variety of aquatic organisms in chronic toxicity studies. Toxicity does, however, correlate with aluminum measurements obtain using the pH 4 extraction method. Natural water and wastewater frequently contain significant levels of suspended solids (25-300 mg/L) containing minerals high in aluminum. Regulatory authorities often recommend measurement of total recoverable aluminum which uses a strong acid digestion. This digestion procedure results in most or all of the inert non-toxic Al present in suspended solids being dissolved and the metal reported as total or total recoverable. This new method (pH 4 extraction) measures aqueous bioavailable aluminum not associated with suspended solids providing a closer approximation of toxic aluminum concentration.
The title and scope are in draft form and are under development within this ASTM Committee.