Valoração ambiental de efluentes de laticínios com cultivo da microalga Phormidium sp.

Abstract

Due to the high demand for energy and fertilizers, there is a need for new technologies to replace finite sources with alternative sources for the production of these compounds. In view of this, microalgae biomasses appear as raw material for the production of biofuels and biofertilizers, and among them, the microalgae Phormidium sp. has this ability to multiply in a medium with the addition of effluents. Thus, the use of alternative media, such as whey, for the cultivation of microalgae reduces the costs of its production and provides a source of organic nutrients for its growth, in addition to removing the contaminating agents of this by product from the manufacture of cheese. The general objective of the study was to seek the valuation of agro-industrial effluents through the cultivation of the microalgae Phormidium sp. in a culture medium with the addition of whey. The concentrations of reducing sugar consumption over time were also quantified, in addition to evaluating the final characteristics of the COD, N and P supernatant. After the cultivation period, a characterization of the produced biomass was carried out in terms of protein and carbohydrate contents. To evaluate the ability of the microalgae Phormidium sp. be cultivated in a culture medium with the addition of whey, tests were carried out with the addition of the residue in a concentration of 1% (v/v) related to the volume of the useful part of the reactor. The time intervals between the additions were varied, from 3, 5 and 7 days, and the cultivation time was 30 days. At the end of the experiment, it was concluded that the microalgae survived the addition of whey, becoming an alternative for valuing the effluent that was previously discarded, because through the concentration readings, a greater microalgal growth can be seen in the additions of whey. In the readings of reducing sugar concentration there was a use of lactose by the microalgae, and in the readings of DQO, N and P also showed that the microalgae Phromidium sp. treated the effluent, as the initial accumulated concentration is greater than the final one. Also, its biomass presented a potential alternative for the production of biofertilizers, causing the dairy industries to use their wastewater in the production of biofertilizers, generating income and reducing expenses with the final disposal of the sludge generated in their treatment.