Water use in industrial activities: Heavy metals and arsenic

M.I. LITTER

Mesa redonda; Reunión liderada por Green Cross Argentina sobre agua y desarrollo; 2018

Pollution due to heavy metals and metalloids is, nowadays, one of the most relevant environmental problems because the annual toxicity of the mobilized metals exceeds the total toxicity of generated radioactive and organic wastes. Species such as chromium, mercury, lead, uranium or arsenic are in the list of priority contaminants of all the environmental agencies. In addition of their natural presence in the environment, as the case of arsenic, the anthropogenic activities, particularly those related to industrial uses (metallurgy, pesticides, fertilizers, paintings, etc.), introduce several hundred of billion tons per year of heavy metals in the terrestrial environment. At the same time, the accumulation of metals in effluents represents significant economic losses in raw materials. Metals have infinite lifetimes, and the chemical or biological methods for their treatment present several restrictions or are prohibitive. The removal and recovery of these species and the growing need of water reuse have been the object of several studies on the removal of pollutants in treatment plants or on the prevention of contamination in the source. Traditional and alternative methods, from biological treatments to physicochemical separation techniques and advanced processes, alone or in combination, can attain almost any desired control degree of the contamination. Thus, purified effluents can be reused for industrial, agricultural, or recreational purposes, or even for drinking water supply. The state of the art of water contamination by heavy metals and metalloids, particularly chromium, mercury, lead, uranium and arsenic, will be described, together with some available proposals for their remediation in water.