Wastewater algae production from

Dodd JC. Algae production and harvesting from animal wastewaters. Agric Wastes 1979 1 23. 

While not specifically related to polyurethanes, a study by Hall and Rao serves as a useful review of the immobilization of algae by various methods. " The reasons for using green and red algae and cyanobacteria are reviewed. Possible applications include the production of fuels, fertilizers, biochemicals, and pharmaceuticals the extraction of heavy metals from aqueous solutions and urban wastewater treatment. 

Repeated application of sludge from the algae pond could result in a progressive accumulation of some toxic elements originally present in the wastewaters fed to the pond. The rate of accumulation of the toxic elements will depend on various site-specific factors such as type of wastewater (municipal wastewater is much less likely than industrial wastewater to contain potentially toxic elements), soil type, texture and pH. It has been estimated that in many areas of the United States, it would require 50 to 80 years before the accumulation of toxic elements reached levels considered dangerous by the EPA for land devoted to food crop production (23). Exceeding these levels of toxic elements would eliminate the possibility of using the land for food crops at a later date. 

One of the important innovations of the PEF concept is that carbon dioxide from the power plant may be introduced into the high-rate oxidation ponds to allow greater production of algae from the wastewater stream. To reach the phosphorus growth potential, it will be necessary both to add carbon dioxide and to maintain nitrogen-fixing species of algae in the pond. 

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