The Real "Scrubbing Bubbles" are Green and Slimy

If you asked most people about their favourite use for algae they might have some trouble coming up with a reply. Although my own preference is to have it wrapped around a tasty California roll, those who don’t share my obsession for this oriental treat might be interested in algae as a versatile ecological engineering tool. In true “But wait, there’s more!” fashion, algal turf scrubber technology is making progress in water quality improvement, reduction of commercial fertilizers, and biofuel production.

            Before delving into its potential for mopping up our planetary mess, what exactly is algae? “Simply” put, algae are “simple” plants. Plants because they are able to make their own food (autotrophic) through photosynthesis, and simple because their tissues are not differentiated in the same way that land plants are. Flowers and trees have tubular structures (vasculature) for nutrient transport and structural support. This includes root systems, leaf veins, and tube structures in trunks or stems. Aquatic algae don’t have this vascular system as their soggy environment creates natural buoyancy and helps move nutrients within the plant. Algae come in many varieties, all the way from single cells to massive kelp forests. The kinds used for algal turf scrubbers are of the “filamentous” variety and are made of long strings of individual cells strung together and resembling clumps of long, slightly slimy hair.

            So how does algal turf scrubber technology work? Essentially, screens of metal mesh are arranged at a slight angle in a waterway such that a shallow layer of water runs over them. Dense colonies of algae grow on these screens, making them look like very soggy grass “turf.” The turfs are “self-seeding” meaning that the natural algal species that grow best in each environment implant themselves on the screen and us bumbling humans just have to watch. As the water runs over the algae mats, the plants do what plants do best: grow. Conveniently enough, the fuel the algae needs to grow is exactly what we want taken out of the water: inorganic nitrogen, phosphorus, and carbon dioxide. The water then flows off the other side of the algae-coated mesh “scrubbed” of these minerals and injected with dissolved oxygen. This process is especially effective in improving waters contaminated by sewage (treatment plants or farm run-off) and commercial fertilizers. In fact, these systems effectively work to fertilize growing algae with the wastes from our homes and farms.

            And now for the promised, “But Wait, There’s More!” All of this scrubbing and growing ends up producing a lot of algae. In fact, the turfs need to be harvested (by regular old garden variety shop-vac) about once a week to ensure the highest levels of growth. The beautiful thing about this technology is that you can use the produced biomass for more green technology. All of that rich, fertilized turf turns out to make great fertilizer itself, without the environmental baggage of commercial fertilizers. The slimy green harvest can also be fermented to methanol, ethanol, butanol, and methane, all of which can be used as alternatives to fossil fuels at a fraction of the cost of producing the same products from corn or soy.

            One man’s waste-water is another algae’s smorgasbord. By using algae to help clean the waters in everything from streams and rivers to areas of ocean, we can come closer to having our beef and feeding it too.