Evaluation and optimization of antiscalant substances for enhanced reverse osmosis performance

Abstract

The advancement of reverse osmosis (RO) technology in water treatment has brought about significant purification benefits. However, the presence of scales poses obstacles to the long-term effectiveness and reliability of RO systems, therefore, the use of antiscalants has emerged as an effective solution. This comprehensive review explores various aspects of scale formations, including their characteristics and prevalence. It delves into detailed understanding of crystal nucleation inhibition, dispersion of crystal growth, threshold inhibition, and inhibition mechanisms, shedding light on the intricate processes involved in successful scale prevention. In addition, this review also explores the realm of antiscalants, uncovering their exceptional potential, mechanisms of action, and game-changing value in RO systems. It takes a thorough evaluation approach to different antiscalant substances, ranging from traditional inhibitors like phosphonates and synthetic polymers to more sustainable and greener inhibitors including biopolymers as promising candidates. The review assesses their efficacy, optimal dosage requirements, and compatibility with varying water pH levels. Moreover, the review highlights the utility of fluorescent-labeled antiscalants to elucidate the mechanisms underlying scale formation and inhibition, revealing the role of “nanodust” particles as primary heterogeneous nucleation centers, and the antiscalants’ role in disrupting the scale formation process. Limitations of current antiscalants and practical challenges, such as antiscalant-induced membrane biofouling, are also highlighted. Furthermore, the review explores options for removing antiscalants from the resulting concentrates. By setting the stage for future antiscalant research, this review offers innovative solutions to overcome existing challenges and achieve higher efficiency in RO systems, emphasizing the important role of synthetic and green polymers as antiscalants.