Wastewater Treatment by Microalgae and Cyanobacteria. The Reduction of the Contaminant Potential of Real Domestic Wastewater: A Case Study

Microalgae can consume high amounts of inorganic nutrients, such as nitrogen and phosphorus, from culture media. This characteristic can be exploited to eliminate nitrogen and phosphorus present in wastewater, and the amount of these contaminants can vary depending on the source. For domestic wastewater, the amounts of nitrogen, phosphorus, and organic matter are low, and its treatment by microalgal cultures can reach high efficiencies. This chapter discusses the treatment of domestic wastewater from Durango City, Mexico, using cultures of Synechocystis aquatilis and Stigeoclonium nanum. The results showed an efficient consumption of nitrogen and phosphorus and a reduction of organic matter (as chemical oxygen demand) and pathogenic bacteria; improvements in pH, conductivity, color, and odor were also observed. Therefore, the use of microalgae and cyanobacteria cultures to treat wastewater from small cities is proposed because of the reduced pollutant potential of the effluent achieved through a simple process.