Cultivation of microalgae in refuse compost and soy-bean waste extracts

Chlorella pyrenoidosa and Scenedesmus quadricauda were cultivated in aqueous extracts of refuse compost and soy-bean wastes, with Bristol medium as a control medium. The compost extract had a lower inorganic nutrient content (total nitrogen, PO₄⁻³, K⁺) and a higher heavy metal concentration (Cu, Zn, Pb and Mn) than the soy-bean extract. C. pyrenoidosa had excellent growth in 2% soy-bean extract and 1% compost extract whereas S. quadricauda required 4% soy-bean extract and 2% compost extract. Compared with the Bristol medium, the waste materials produced, in general, higher total growth and rates of growth with both algae, especially the soy-bean waste.
The contents of chlorophyll, protein, carbohydrate, phosphate and heavy metals in the algal products were determined. Because of the higher algal yield and protein content, and lower level of heavy metals in the algae harvested from the soy-bean extracts, it is recommended that this waste be used for producing feed-grade protein. Copyright © 1985 Published by Elsevier Ltd.