Microalgae–Bacteria system for biological wastewater treatment

Abstract

Use of microalgal–bacterial consortium in biological wastewater treatment can represent a feasible alternative for sustainable wastewater treatment requirements and support for algal productivity. the advantages emerge from the ability of microalgal taxa to perform photosynthetic process and achievement of nutrients exchange between microalgae and bacteria cells. a mixed consortium wild-type microalgae (such as Chlorella sp.) and bacteria was tested for biological treatment of dairy industry wastewater in stirred tank batch bioreactor. the aim of the experiment was to assess the feasibility of the biological system in terms of treatment performances, growth rate and microalgae removal. At the end of the treatment cycle (96 h) the removal efficiency of organic matter (COD–Cr), total nitrogen (TN) and total phosphorus (TP) were 91, 68 and 38%, respectively. the maximum microalgal and microalgal–bacterial system growth rate were 0.13 and 0.10 day–1, respectively. the highest removal of microalgal cells was about 63% recorded after 72 h of batch treatment. the use of microalgal–bacterial consortium for wastewater treatment can be promoted as a cost efficient biotechnology in terms of high organic matter and nutrients removal by aeration costs elimination, the major drawback so far being represented by the poor microalgae cells removal from effluent.