Microalgae Cultivation Using Offshore Membrane Enclosures for Growing Algae (OMEGA)

• 作者: Brandi McKuin Colin Beal Emil Geiger Hiromi Kagawa J. Elliot Campbell John Malinowski Jon Rask Jonathan D. Trent Kit Clark Linden Harris Matthew A. Claxton Patrick Wiley Russel Adams Sasha Tozzi Sigrid Reinsch Tra-My Justine Richardson Tsegereda Embaye Zbigniew Kolber
• 来源期刊: 可持续生物质能源系统(英文)
• 学科: 医学
• 关键词: Biofuels Wastewater Treatment MICROALGAE PHOTOBIOREACTOR CO2 Mass Transfer Fast REPETITION Rate FLUOROMETRY Instrumentation and Control
• 年，卷（期）: 2013,（1）
• 页码范围: 18-32
• 页数: 15页
• 分类号: R73

摘要

OMEGA is a system for cultivating microalgae using wastewater contained in floating photobioreactors (PBRs) deployed in marine environments and thereby eliminating competition with agriculture for water, fertilizer, and land. The offshore placement in protected bays near coastal cities co-locates OMEGA with wastewater outfalls and sources of CO2-rich flue gas on shore. To evaluate the feasibility of OMEGA, microalgae were grown on secondary-treated wastewater supplemented with simulated flue gas (8.5% CO2 V/V) in a 110-liter prototype system tested using a seawater tank. The flow-through system consisted of tubular PBRs made of transparent linear low-density polyethylene, a gas exchange and harvesting column (GEHC), two pumps, and an instrumentation and control (I&C) system. The PBRs contained regularly spaced swirl vanes to create helical flow and mixing for the circulating culture. About 5% of the culture volume was continuously diverted through the GEHC to manage dissolved oxygen concentrations, provide supplemental CO2, harvest microalgae from a settling chamber, and add fresh wastewater to replenish nutrients. The I&C system controlled CO2 injection and recorded dissolved oxygen levels, totalized CO2 flow, temperature, circulation rates, photosynthetic active radiation (PAR), and the photosynthetic efficiency as determined by fast repetition rate fluorometry. In two experimental trials, totaling 23 days in April and May 2012, microalgae productivity averaged 14.1 ± 1.3 grams of dry biomass per square meter of PBR surface area per day (n = 16), supplemental CO2 was converted to biomass with >50% efficiency, and >90% of the ammonia-nitrogen was recovered from secondary effluent. If OMEGA can be optimized for energy efficiency and scaled up economically, it has the potential to contribute significantly to biofuels production and wastewater treatment.