Enhanced microalgal biofilm formation and facilitated microalgae harvesting using a novel pH-responsive, crosslinked patterned and vibrating membrane

Abstract

Harvesting efficiency is one of the key issues restricting the further commercialization of microalgae. Traditional biofilm studies only tend to focus on enhancing biofilm formation, while neglecting the subsequent harvesting of the biofilm. In this study, a win-win strategy for high-density microalgal cultivation and low-cost harvesting through biofilm cultivation on a pH-responsive, charge-switchable, patterned membrane was investigated using a polyethylenimine (PEI)-crosslinked polyvinylidene fluoride (PVDF) membrane. The patterned membranes were prepared by spray-modified non-solvent induced phase inversion, and the effect of pattern height on biofilm formation and microalgal harvesting was investigated. The PEI-crosslinked PVDF membrane surface was positively charged below pH 8 and negatively charged above pH 9, resulting in a higher attractive energy A c c e p t e d M a n u s c r i p t 2 below pH 8 and a repulsive energy above pH 9 according to the extended Derjaguin, Landau, Verwey, Overbeek model. Patterning of these membranes increased the active area for microalgal attachment, and created a low-shear area in the valleys that prevents early detachment of microalgal cells. Membranes with a higher pattern height resulted in faster biofilm development and increased final biomassaccumulation. Low-energy membrane vibration was applied to enhance cell detachment. pH=7 was found to be the optimal pH for enhanced microalgal biofilm formation on PEI-crosslinked patterned membranes, and a switch to pH=10 was best for microalgal harvesting.

Highly Active Ni Nanocatalysts Derived from Metal–Organic Framework (Ni-BDC) Boosted Deoxygenation and Cracking of Fatty Acid Methyl Esters

“…As feedstocks for third-generation biofuels, microalgae exhibit advantages of a high photosynthetic efficiency, a high lipid content, and cost-effectiveness. − Microalgal biodiesel has attracted immense interest because of its non-toxicity, biodegradability, and low pollution and emissions. , However, as the main components of biodiesel, fatty acid methyl esters (FAMEs) exhibit a high oxygen content, a long molecular chain (≥C 16 ), and poor low-temperature mobility. , Therefore, it is crucial to conduct subsequent deoxygenation (DO) and cracking processes to form jet fuel (C 8 –C 16 ) with better combustion performance, which is suitable for the aviation industry. , …”

Symbiotic relationship between filamentous algae (Halomicronema sp.) and extracellular polymeric substance-producing algae (Chlamydomonas sp.) through biomimetic simulation of natural algal mats

“…Generally, harvesting microalga cultures is expensive, and biofilm-type culture methods are widely applied to address this problem; however, further research on aspects of its production, such as efficient harvesting and unit price reduction is required ( Witarsa et al, 2020 ; Zhao et al, 2021 ). Watari et al (2021) confirmed that mixing microalgae and bacteria in biofilm maximizes carbon absorption and biomass production, and reduces costs ( Wicker et al, 2022 ).…”