ABSTRACT
Solid retention time and hydraulic retention time influence the biomass concentration and the overall productivity of the microalgal-bacterial systems. The main difference between an algal system and a microalgal-bacterial consortium in terms of nitrogen removal is the removal pathways. The symbiosis between microalgae and bacteria offers a large potential for the treatment of nutrient rich wastewaters, although some aspects need to be taken into account, as they determine the nutrient removal efficiencies or the nutrient removal pathways. The selection of a particular strain for wastewater treatment is a decisive step when engineering a consortium of microalgae and bacteria. Light is the energy source to perform photosynthesis, allowing microalgae growth. Indoor cultures and closed photobioreactors use other sources of light different from sunlight. pH is one of the most important parameters in microalgal cultures, as it determines the solubility of carbon dioxide, removal of other nutrients like P and N, and most importantly it affects the metabolism of the microalgae.
