Investigation of Algal Biotoxin Removal during SWRO Desalination through a Materials Flow Analysis

Abstract

Abstract:The operation of seawater reverse osmosis (SWRO) desalination facilities has become challenged by the increasing frequency and severity of harmful algal blooms (HABs). The efficiency of algal toxins removal during SWRO and pretreatment processes has critical human health implications. Therefore, a probabilistic materials flow analysis (pMFA) was developed to predict the removal of algal toxins in source water by various pretreatment configurations and operations during SWRO desalination. The results demonstrated that an appreciable quantity of toxins exists in the SWRO permeate (ng/L-µg/L levels), the backwash of pretreatment, and final brine rejects (µg/L-mg/L levels). Varying the pretreatment train configuration resulted in statistically significant differences in toxin removals, where higher removal efficiencies were evidenced in systems employing microfiltration/ultrafiltration (MF/UF) over granular media filtration (GMF). However, this performance depended on operational practices including coagulant addition and transmembrane pressures of MF/UF systems. Acute human health risks during lifetime exposure to algal toxins from ingestion of desalinated water were benign, with margins of safety ranging from 100 to 4000. This study highlights the importance of pretreatment steps during SWRO operation in the removal of algal toxins for managing marine HABs.

Simulation of Reverse Osmosis Process: Novel Approaches and Development Trends

“…In certain works, the other approaches, which cannot be related to the described above groups, were applied. Those models can be based on the empirical data (both with and without combination with conventional models) [329][330][331][332][333][334][335][336], the mass and energy balances [337][338][339][340][341], the Monte-Carlo method [342][343][344], the concentration polarization models [345][346][347] and osmotic pressure [348], the boundary layer theory [349], the dynamic modeling [350], the materials flow analysis [351], the risk and fault analysis [352][353], the numerical methods [354], the chemical kinetics and equilibrium [355], or its combinations [356]. However, such investigations were low numerous and it does not seem possible to define some of them as perspectives.…”