Sustainable antiscalant for municipal reverse osmosis plants

Abstract

Restrictions on the discharge of reverse osmosis brines containing phosphorus compounds that promote eutrophication are continuously increasing, and the related regulations are becoming more stringent. The low biodegradability and the phosphorous content of the phosphonate-based antiscalants are some of the first reasons for the growing concern about their environmental impact when discharged into natural ecosystems. To address this issue, a broad-spectrum biodegradable and phosphorus-free antiscalant has been developed for inhibiting scale formation in municipal reverse osmosis applications in both brackish water and seawater plants. The study evaluated the biodegradability of the green antiscalant, demonstrating it is inherently biodegradable. A dosing model for the green antiscalant and a scaling potential reduction model for sparingly soluble species model were developed. These models cover a wide range of scaling potentials applicable to both brackish water and seawater conditions, enabling precise calculation of the minimum required antiscalant dosage for effective protection against scaling. Experimental tests in a reverse osmosis pilot plant validated the effectiveness of the green antiscalant in preventing scaling. Membrane autopsies confirmed the successful prevention of scaling. The results evidenced that the green antiscalant is a sustainable and cost-effective solution for membrane scaling control in municipal reverse osmosis applications. Its use can contribute to reliable and efficient water supply while reducing the environmental impact compared to antiscalants containing phosphorous compounds.