Harmful algal blooms (HABs) are a serious environmental issue worldwide. HABs occur when water conditions (temperature, solar insolation, and nutrients) foster rapid growth of microalgae (cyanobacteria). When microalgae reach high concentrations, the sunlight is blocked, preventing photosynthesis. This results in microalgae death, which releases endotoxins that contaminate the water. The purpose of the microalgae harvesting project at Utah Valley University is to design, build, and test a direct microalgae harvesting barge that can be deployed on the water to target problem areas. The harvesting barge will extract the microalgae from the water, preventing an HAB, and reducing the nutrient content of the water. Ultimately, the harvested algae will be used as a carbon-neutral biofuel.<br/> <br/>We have designed, built, and tested seven, lab-scale, microalgae harvesting technologies. We tested the effectiveness of each technology at removing low concentrations of microalgae from water over time. Of the seven technologies tested, only two of the technologies were deemed effective: 1) a continuously-swept cellulose filter we designed and 2) a conventional plate and frame filter press with body addition of cellulose. We determined the cost and time required to scale-up our continuously-swept filter made it less favorable to using a conventional plate and frame filter press. We have designed a full-scale, 10 foot wide x 30 foot long, algae harvesting barge. It will filter 1.73 million gallons of water during each 16 hour day, removing 590 kilograms of dry algae (at an average algae concentration 0.1 gram per liter). The barge can filter 1 square mile of water every 20 days. We envision a fleet of barges operating globally to prevent algal blooms. We will use the harvested algae/cellulose filter cake as a carbon-neutral biofuel to produce electricity. We hope to deploy the prototype microalgae harvester on Utah Lake in the spring of 2019.

Direct microalgae harvesting to prevent harmful algae blooms and produce renewable biofuel

2019 Spring National Meeting

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