In Growing Algae for Biofuels, It Matters Who Used the Water Last
by Sarah Loftus (Nanowerk News/Duke University) … Although biofuels made from algae provide numerous environmental benefits, they will not win market share until they can compete economically with cheap fossil fuels.
Algae require tremendous volumes of water to grow, and reusing that water makes production cheaper (“Water use and its recycling in microalgae cultivation for biofuel application”). However, researchers have disagreed on how recycled water affects algae. Some scientists have found that it inhibits growth, others found that it improves growth, and many found that it has no effect.
As a researcher focused on algae cultivation, I wanted to find an explanation for these different results, which could reveal optimal strategies for growing algae. In a recently published study (“Cross-study analysis of factors affecting algae cultivation in recycled medium for biofuel production”), I found that algae growth success was highly linked to the type of algae previously grown in the reused water. This knowledge could help us choose which algae to grow to make a more competitive fuel source. Though it may seem like a minor adjustment, finding the most effective and economical production methods is an essential step in moving any technology from the lab to the market.
Recycling cultivation water saves water and money, but poses other challenges. Algae secrete molecules into their liquid habitat as they grow (“Dissolved organic matter (DOM) release by phytoplankton in the contemporary and future ocean”), just as people leave behind dead skin cells, mucus, and other wastes. Algae can also break open when they die, releasing their innards.
Some researchers have found that the build-up of these algae “juices” in recycled water interferes with future algae growth (“Influence of culture medium recycling on the performance of Arthrospira platensis cultures”). But other researchers found that algae grow perfectly well (“Evaluation of flocculation induced by pH increase for harvesting microalgae and reuse of flocculated medium”), or even better (“Pilot-scale continuous recycling of growth medium for the mass culture of a halotolerant Tetraselmis sp. in raceway ponds under increasing salinity: A novel protocol for commercial microalgal biomass production”), in recycled water. READ MORE Abstract (Algal Research)
Target Cultivation and Financing Parameters for Sustainable Production of Fuel and Feed from Microalgae (Enviromental Science and Technology)
Water use and its recycling in microalgae cultivation for biofuel application (Bioresource Technology)