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.
막 여과 방법의 주된 문제점은 막간차압과 에너지 소모량을 높이는 생물학적 부착물이다. 본 연구에서는 미세조류가 고농축으로 수확되는 과정 중에 막 외부와 내부에서 발생하는 생물학적 부착물을 줄이기 위하여 친수성 고분자인 poly-4 vinylpyridine (p4VP)를 상업용 막 표면에 코팅하여 미세조류 수확효율을 높이고자 하였다. 코팅 방법으로 기상 증착 공정인 initiated chemical vapor deposition (iCVD) 공정을 이용하여 일반 코팅 방법의 문제점인 용매에 의한 불순물, 용매에 의한 손상, 균일성을 해결하고자 하였다. 그로인해 생물학적 부착물을 높이는 막 표면의 roughness를 줄이고, 막의 친수성을 높임으로써 미세조류의 종 중 클로렐라 불가리스를 순환 (cross-flow) 막 여과 방식으로 수확하여 보았을 때 생물학적 부착물에 의해 발생하는 케이크, 흡착, 막의 저항이 어느 정도 감소하는지 확인하였다.
