Cultivo de microalgas em fotobiorreator e reator misto visando a biorremediação e produção de biocombustíveis.

Abstract

This paper aimed to improve the tubular fotobiorreator type bubble column bench and produce a mixed system for cultivation of microalgae, aiming the bioremediation and biofuels production. As a way of cultivate it was used the effluent coming from the Wastewater Treatment Plant – UNISC. To monitor cell density and dry weight, it was standardized a method using a spectrophotometer (ʎ=682 nm) with a correlation coefficient R2>0,98. In the biomass recovery, it was evaluated the electroflotation method and it was produced an electrode of iron plates. After improving the fotobiorreator tubular bench there was an increase in cell density and dry biomass of approximately 1.80 times. Using the method of enzymatic transesterification in situ, it was possible to verify all the bioconversion of lipid extracted material that was confirmed by analysis on HPLC and CG-MS. For the production of ethanol it was used fungi filamentous concerning the microalgae biomass hydrolysis, followed by fermentation of Saccharomyces cerevisiae. With the construction of a phototype system for the mixed culture of microalgae, there has been the development of various strains of microalgae, achieving maximum cell density of 25.48 x106 cells mL-1 dry biomass of 0,62 g L-1 and lipid percentage of 1.36 % (without contribution of CO2). Already with CO2 injection, in 15 days of cultivation, the maximum cell density was obtained up to 26.97 x 106 cells mL-1, dry biomass 0.72 g L-1 and lipid percentage of 6.07 %. In assessing the bioremediation of effluent using mixed system for the cultivation of microalgae without contribution of CO2 , there was significant reduction in the parameters of alkalinity, total phosphorus, ammonia nitrogen and total Kjeldahl nitrogen, however, there was an increase in the DBO5 and DQO patterns. With the injection of CO2 , the results were: alkalinity and DQO increasing, ammonia nitrogen decreasing, total Kjeldahl nitrogen and DBO5 In the last experiment, the phosphorus concentration remained unchanged. Thus, it can be concluded that the proposed systems are suitable for the production of microalgae, the bioremediation of waste and the consequent production of biofuel.