Scientists call the pervasive overgrowth of red algae, like pseudo-nitzschia, a “bloom.” Known by the ominous name of “red tides,” blooms produce a toxin known as domoic acid that is harmful to animals and humans, threatens marine ecosystems and wreaks havoc with the fishing industry in affected areas.
During the summer of 2015, the largest red algae bloom on record grew in the warm waters off the coast of California. This algal bloom, unusually dense and more poisonous than others, now stretches north to Alaska and promises severe repercussions for the Pacific Coast fishing industry. The state of Washington recently closed public and commercial fishing of its popular Dungeness crab due to the toxic levels found in the marine life.
Invasive algae blooms can kill fish, marine life and birds, and cause human illness. Blooms manifest in large bodies of water, affecting coastal states, the Gulf of Mexico, Great Lakes, inland waterways and even tropical wetlands like the Everglades in Florida, where the organisms can flourish in the warm waters. According to the National Oceanic and Atmospheric Administration (NOAA), toxic blooms have an economic impact in the United States of $82 million every year, affecting not only the fishing industry but recreation and tourism as well. Given the harsh economic impact to coastal communities, and the widespread regions affected, scientists study the phenomenon to develop ways to reduce the impact and control the growth of red algae.
Perhaps a silver lining exists in these happenings and we need only to recognize their value. What if red algae blooms in the ocean could be contained, the plant material recovered and turned into biofuel to help solve our fossil fuel energy challenges? The forerunner to this process is already in progress, one of which is run by Ohio State University’s College of Food, Agricultural and Environmental Sciences. The farming of red algae on otherwise non-productive farmland miles away from the oceans turns the blooms into biofuel, bio-plastics, food supplements and other products. The natural next step may be the recovery of ocean algae.
An algae drying process could remove the moisture from red algae blooms in an efficient and cost-effective manner. The process would dry the wet biomass material enough such that a further manufacturing process, similar to that used in algae farming, could then create the biofuel. As a side benefit, making biofuels out of algae potentially helps soybeans and corn as food crops, saving the large input of fossil fuels they need through the use of fertilizers and in planting and harvesting.
Industrial drying equipment like the rotary dryer, consisting of a rotating cylindrical shell, is ideal for this process. The shell is slightly inclined from the horizontal, and equipped with lifting flights on its interior. The wet algae is fed into one end of the rotating shell, is conveyed along the length of the shell as it dries, and is discharged from the other end. As the material passes through the rotary shell, it is lifted and dropped by the flights, exposing it to a hot gas stream flowing through the shell to dry it.
Heyl & Patterson rotary dryers are among the most versatile available, capable of handling almost any bulk solid material, regardless of its conveyance and handling characteristics. These industrial dryers can be configured to meet a wide range of needs and applications. Factors such as starting and final moisture content, product temperature, drying air temperature, air velocity and retention time are all considered in the specifications of the dryer. Applications and designs can be investigated in our pilot plant testing facility. Whatever the properties of the material needed to dry, Heyl & Patterson will design and manufacture a rotary dryer that will meet the application objectives.