Effects of membrane orientation on fouling characteristics of forward osmosis membrane in concentration of microalgae culture

Abstract

Application of forward osmosis (FO) membrane to microalgae cultivation processes enables concentration of microalgae and nutrients with low energy consumption. To understand fouling characteristics of FO membrane in concentration of microalgae culture, we studied flux decline, flux recovery by cleaning, and foulants characteristics, in different membrane orientation of active-layer-facing-feed-solution (AL-FS) and active-layer-facing-draw-solution (AL-DS) modes. Batch concentration of Chlorella vulgaris was conducted with a cellulose-triacetate FO membrane. Rapid flux decline and lower flux recovery was observed in AL-DS mode because of inner-membrane fouling including internal pore clogging, adsorption and internal concentration polarization in the support layer. A proportion of polysaccharides in extracellular polymeric substances to soluble microbial products were larger in chemical cleaning effluent than physical one in AL-DS mode, although those were not significantly different in AL-FS mode. Excitation-emission matrix analysis revealed that proteins and humic-like substances were also possible irreversible foulants both in AL-DS and AL-FS modes.

Electricity Generation and Pollutants Removal of Landfill Leachate by Osmotic Microbial Fuel Cells with Different Forward Osmosis Membranes

“…It can be seen from Fig. 1B respectively, which might be due to more serious membrane fouling and faster drop of water ux on AL-DS mode [22].…”

Modeling and Simulation Studies Analyzing the Pressure-Retarded Osmosis (PRO) and PRO-Hybridized Processes

“…As the composition of solutes gets intricate, the interactions among the solute compounds or organisms aggravate the performance of a membrane. For example, the microbes in the feed and draw solutions produce byproducts such as polysaccharides and proteins [13]. Such byproducts get accumulated inside a membrane and result in a severer ICP.…”

“…While the PRO process has achieved appreciable technological advances in a number of research projects, nevertheless, several obstacles still hamper the commercialization of the process. For example, multiple types of research concluded that a stand-alone PRO process was not viable due to the inherent thermodynamic limits [9][10][11][12] and the vulnerability of a membrane to the fouling propensity [13][14][15][16][17][18][19]: the inherent thermodynamic limits and the vulnerability of a membrane to the fouling propensity will be elaborated in the upcoming sections.…”

“…By applying the hybridization strategy to PRO, the vulnerability of a PRO membrane to fouling can be mitigated because of pretreatment deployed prior to a desalination process. Furthermore, the energy consumed by a desalination process can be recovered partially by a PRO process [13,14]. Due to these advantages, PRO hybridized processes were rapidly seen as a promising process type.…”

Polarity-Molecular Weight Profile of Extracellular Polymeric Substances in a Membrane Bioreactor: Comparison between Bulk Sludge and Cake Layers

“…EPS are usually fractionated into three forms: soluble EPS or soluble microbial products (SMP); loosely bound-EPS (LB-EPS), which are present outer layer of EPS matrix; and tightly bound-EPS (TB-EPS) which are present in the inner layers of the EPS matrix [3]. Several review papers have highlighted roles of EPS in treatment performance of biological wastewater treatments such as conventional wastewater treatment, membrane bioreactor (MBR) [2], and forward osmosis membrane processes [4]. They have proved the fact that EPS considerably affect properties of activated sludge, directly determining charge, hydrophobicity/ hydrophilicity and adhesion ability of sludge surface [5].…”