Chapter 13 - Impact of Algal Blooms and Their Toxins on Reverse Osmosis Desalination Plant Operations

Abstract

Seawater desalination by reverse osmosis (RO) has emerged over the past few decades as a reliable and necessary method for augmenting drinking water supplies in many parts of the world. As freshwater resources become limited due to global climate change, rising demand, and exhausted local water supplies, seawater desalination will play an increasingly important role in securing the world’s future water supply. The global increase in occurrence and incidence of harmful algae blooms is a concern for RO desalination plants due to the high biomass of microalgae present in ocean waters during these events, and a variety of deleterious substances that some algae produce. The compounds range from innocuous substances that can cause membrane fouling, to noxious compounds and powerful neurotoxins that constitute significant public health risks if they are not effectively and completely removed by RO membranes. Algal blooms can cause significant operational issues that can necessitate costly pretreatment procedures, result in increased energy usage due to membrane fouling, and in extreme cases, require a plant to be removed from service. Early algal bloom detection by desalination facilities is essential so that operational adjustments can be made to ensure that production capacity remains unaffected. This chapter will focus on characterizing a range of substances of concern to desalination facilities, their known producers, and our present state of knowledge regarding substances of particular concern due to their toxicity. Also included is a case study from southern California, which involved the monitoring of intake and desalinated water from a pilot SWRO desalination facility, and bench-top SWRO experiments modeled the worst-case scenario toxic events for the local area.