Cross-flow filtration for harvesting microalgae with surface modified polymer membrane

Abstract

Production of microalgae-based biomass has received an incessant attention from the world because of its potential for $CO_2$ fixation, transportation fuel, and numerous high-value products. To reduce its production process cost, one solution is to develop an economical and efficient harvesting method. Membrane filtration is a cheap and simple harvesting process which can achieve a high retention of biomass without contaminating the end-products of microalgae

however, it has a major constraint which is the fouling formation that leads to lower efficiency of the filtration. The purpose of the present study is to reduce fouling by means of surface-coating (initiated chemical vapor deposition, iCVD) with a functional polymer, i.e., hydrophilic poly-4 vinylpyridine (p4VP). The hydrophilic polymer was selected as the final option after its effectiveness on improving membrane performance was proved via polymer screening. Accordingly, the effectiveness of different coating thickness, 0, 50, 200, 400, and 700 nm, on steady-state flux of algae suspension (Js) was investigated. About 33% of Js increased with 200 nm of coating compared to the un-modified membrane as adsorption resistance largely decreased. From the membrane characterization, the reduction of mean roughness of the membrane surface from 311 nm to 280 nm was observed with 200 nm of coating without any loss of surface porosity. Furthermore, the recyclability of the surface modified membrane was investigated, and p4VP coating was found to extend the span of membrane’s usability for more economical harvesting.