Nutrient removal by Arthrospira platensis cyanobacteria in cassava processing wastewater

Abstract

Industrial processing of cassava and other starch-containing tubercles generates high amounts of nutrient-rich wastewater that cannot be directly disposed in rivers or lakes. This work evaluates the bioremediation of cassava processing wastewater using the cyanobacteria Arthrospira platensis, focusing on removing nitrogen and phosphorous sources. An experimental design was carried out comprising treatments consisting in the feed of 0.0–2.0 mL/day of cassava processing wastewater per liter of culture in a feed-batch operation. The experiments were carried out at pH 11.0 and 23 °C. The effects of cassava processing wastewater were evaluated on the number of trichomes, growth rate, number of divisions per day, generation time, and nutrient consumption by the cyanobacteria. Arthrospira platensis bioremediation had improved performance at 1.5 mLwastewater/day/Lculture of cassava processing wastewater regarding the growth of colonies and removing nutrients from the wastewater. The treatment at low feed rates resulted in total removal of ammonia and nitrites, and partial removal of nitrates and phosphates. The result indicates that Arthrospira platensis could be applied in bioremediation of agroindustry wastewaters that contain high concentrations of nitrogen sources, especially ammonia and nitrites. However, industrial treatment should be carried out in stabilization ponds due to the low required feed rate for optimal removal of nutrients.