Enhancing the shelf life of natural scale inhibitors using bio preservatives

One of the key challenges in using natural extracts for water treatment is their biodegradability and susceptibility to microbial spoilage, which can limit storage and long-term effectiveness. This study investigates the scale inhibition capabilities of an aqueous extract of Salvia rosmarinussp through electrochemical measurements, conductivity tests, and morphological examination. Additionally, two natural substances, Rhamnolipid and Chitosan, were evaluated as bio-preservatives to prevent mold growth and enhance the shelf life of the rosemary extract. The reasons for selecting these specific bio-preservatives include their known antimicrobial properties, antioxidant effects, environmental benefits, and suitability for the intended application. For 24 weeks, we conducted a microbial examination and assessed the anti-scaling performance of the extract in combination with the bio-preservatives. The results demonstrate that rosemary extract significantly inhibits CaCO₃ scale precipitation, attributed to the presence of carboxylate and hydroxyl groups which effectively chelate cations and disturb the normal crystal growth of the scales. Additionally, the rosemary extract-chitosan mixture exhibits superior antimicrobial and anti-scaling performance compared to the rosemary extract-rhamnolipids combination over six months. It can be concluded that a 1:2 ratio of chitosan to rosemary extract provides an effective eco-friendly scale inhibitor and reduces the growth of pathogenic bacteria and fungi with an extended shelf life. In this context, biosurfactants and polysaccharides present beneficial properties that offer sustainable and biological alternatives to conventional chemical biocides.