Review on an integrated pre-treatment system to reduce membrane accelerated biofouling during red tide occurrences in Oman

Abstract

The increasing pressure on available freshwater resources to meet the demand for all human activities raised the importance of finding new water resources. Desalination of seawater and water reuse considered the most reliable sources of fresh water. Seawater desalination is a high-powered consuming process therefore seawater reverse osmosis desalination is currently the most widely implemented technology because of its lower power consumption compared to thermal desalination also it requires less footprint, generates less waste, and has reliable performance. To ensure preserving high performance of Seawater reverse osmosis (SWRO) plants, there is a need for an active pre-treatment system to deliver a continuous good quality feed for the RO membranes. Among various issues faces the use of RO membranes like chemical attack and scaling of membrane, but membrane fouling is the most challenging issue. As per the literature study, there are various pre-treatment systems implemented worldwide in SWRO plants and they are classified as conventional technologies including coagulation, sedimentation, media filtration, and flotation or membrane-based technologies like microfiltration, ultrafiltration, and nanofiltration. Conventional systems are more complex to design & operate, require a high footprint, and are better option when seawater has high contents of oil and organic matters. While membrane-based systems have less space requirements, simple to operate, and more effective for particulate matter removal but they are costly and sensitive for algal bloom. This comprehensive review study focusses on feasibility of utilizing Dissolved Air Flotation (DAF) in an integrated system that combines conventional and membrane pre-treatment systems to provide a decent quality feed water for SWRO. Integrated system is proposed as a pre-treatment system because dissolved air flotation characterized by high organic foulants removal and membrane-based pre-treatment are reliable and have high permeate flux.