The Use of Algal-Scrubber Technology in the Treatment of Dairy-Processing Wastes

This proposal would establish a pilot-scale algal scrubber to treat secondary discharge from dairy-processing plants. Algal scrubbers are fixed-media structures for culturing periphyton communities with two major components: an autotrophic assemblage of microscopic, filamentous algae, and an association of heterotrophic bacteria and protozoans. Under conditions favorable to photosynthesis, the algal component is able to clear mineral nutrients from effluents with great efficiency, whereas the heterotrophs can metabolize dissolved organic either simultaneously or in darkness. Algal scrubbers thus hold unique potential for processing phosphorus and BOD, two pollutants highly concentrated in dairy-plant wastes. Because the U.S. dairy industry is under pressure to meet increasingly stringent discharge standards, it is necessary to develop innovative, economical, and environmentally sustainable technologies for handling secondary effluent from on-site treatment facilities. Research proposed here would contribute to this effort by testing algal-scrubber response to elevated concentrations of such sewage. Scrubber performance in pollutant clearance would be measured by chemical analysis of water-samples. Dry-weight biomass, chlorophyll a content, and algal species distributions would monitor composition and stability of the scrubber community. Results are expected to indicate effluent dilutions and algal-scrubber areas required for reliable treatment of these discharges.