Immersed hollow fibres microfiltration (MF) for removing undesirable micro-algae and protecting semi-closed aquaculture basins

Abstract

In this study, an original use of immersed microfiltration membranes (mean pore size equal to 0.2 μm) is investigated for the total removal of toxic dinoflagellates from seawater. Using a membrane autopsy and fouling model approach and the use of fouling indexes (called Pore Blocking Index, Pore Constriction Index and Cake Filtration Index), three dinoflagellate suspensions (Heterocapsa triquetra, Alexandrium minutum and Prorocentrum lima) have been microfiltered in order to study the influence of micro-algal species and its concentrations (1,000 and 30,000 cells/mL) on filtration yield and membrane fouling mechanisms. Results showed that all micro-algae have been retained after 180 min of microfiltration. At 30,000 cells/mL, permeate fluxes declined rapidly and an internal fouling occurred at the beginning of microfiltrations followed by a cake deposition. At 1,000 cells/mL, flux declined slowly and was mainly due to an internal fouling. For a given micro-algae concentration, the filtration behaviour and fouling behaviour can be very different based on the micro-algae species. The dissolved organic substances and particulate size distribution are important factors affecting internal but also external fouling. SEM analyses and fouling indexes are useful tools, simple to implement, and allow the study of membrane fouling and membrane process optimization. Research highlights : ► Removal of toxic dinoflagellates from seawater using a low energy consumption membrane process. ► Microfiltration for safe shellfish storage during toxic micro-algae bloom. ► Retention of 99% of micro-algae by immersed microfiltration membrane. ► Understanding of membrane fouling mechanisms to process optimization.

Analysis of UF membrane fouling mechanisms caused by organic interactions in seawater

“…The membrane fouling potential of seawater algae during bloom periods have been well documented (Castaing et al, 2010(Castaing et al, , 2011Ladner et al, 2010), and effective mitigation methods involving chemical pre-treatment have been devised (Villacorte et al, 2009). However, improvements are still needed in understanding EPS fouling mechanisms and its interactions with other seawater organic matter.…”

A novel sintered metal fiber microfiltration of bio-ethanol fermentation broth

“…1, the major applications of microfiltration are situated at different levels, i.e. (i) in the harvesting and pre-treatment of algal biomass, hence in item [1]; (ii) to filtrate the broth before the distillation (and pervaporation, in a hybrid system), hence after item [3]; and (iii) to perform a final filtration step of the wastewater treatment, hence integrated in item [7]. The benefits of introducing membrane techniques are now recognized, although extensive research is still needed to scientifically and economically justify their application.…”

Continuous Ethanol Fermentation in Immersed, Cross-Flow Microfiltration Membrane Bioreactor with Cell Retention

“…The ZeeWeed ® MBR uses immersed hollow-fiber membranes to carry out ultrafiltration, mainly of waste water systems to produce high-quality permeates. Immersed hollow-fiber MF was used for removal of toxic substances from seawater [12] and for graywater treatment [13]. Ethanol fermentation using cross-flow microporous membranes to ferment sugars, i.e.…”