Exploring the link between antiscalant and fouling variation from reverse osmosis pilot study

Abstract

Access to pure water has shaped human civilization for centuries. Growing water scarcity has accelerated the development of sustainable purification technologies like Reverse Osmosis (RO). Despite significant advancements, membrane fouling remains a major bottleneck in RO systems. Scaling, among the different fouling types, became the main challenge in groundwater desalination, leading to the widespread use of antiscalants in RO operations. However, these antiscalants come with challenges, including incompatibility, concentrate disposal, and the risk of synergistic fouling. In response to environmental concerns, polymeric and biodegradable “Green” antiscalants have been studied for RO systems. However, a lack of pilot evaluations and a limited understanding of the antiscalant structure to foulant relationship have significantly hindered RO operational efficiency. This study evaluates three antiscalants in relation to pilot performance, RO membrane fouling, and cleaning strategy. Two commercial antiscalant blends (phosphonate salt and polymeric) and a novel "Green” antiscalant," polyglycerol maleate, were evaluated over an eight-month pilot study, capturing seasonal performance variations. The study revealed distinct, manganese-to aluminum-dominated fouling, depending on the antiscalant interactions. Additionally, a biofouling quantification method and concentrate line analysis are introduced. The cleaning study showed that while some foulants resist simple cleaning techniques, cleaning at a lower foulant uptake can reduce long-term membrane deterioration highlighting the need for optimized cleaning with foulant types. Overall, from feed water analysis to cleaning, this study provides a complete operational picture of fouling and a framework for future antiscalant-RO system studies.