Use of Natural Coagulants/Flocculants in the Treatment of Hospital Laundry Effluents

Water is a fundamental substance for the existence of life on earth. However, globally there is a freshwater crisis. Hospitals generate exorbitant volumes of effluents (5 to 15 times more toxic than urban ones). Hospital laundry is known for demanding the highest volumes of water, generating a proportional amount of complex effluents with high toxicity and recalcitrance. Adequate treatment for hospital wastewater is always an essential solution. Among all treatment methods, coagulation/flocculation emerges as one of the best alternatives. However, the use of traditional compounds such as aluminium sulfate has caused secondary pollution; its residues are harmful to public and environmental health. In this sense, the present study used natural compounds that do not cause adverse effects, such as chitosan/hydroxyapatite, to clarify the laundry effluents of the largest hospital from the Tocantins. The results showed that the hydroxyapatite associated with chitosan, at pH 6 and dosage of 50 mg/L, reduced the turbidity and apparent colour of these wastewaters by up to 67 and 55%, respectively. With lower performance and higher dosage (60 mg/L), the chitosan gel used (pH 6) promoted a maximum reduction of 35% of the apparent colour and 40% of turbidity.