COMPARATIVE STUDY OF THE INFLUENCE OF BREWERY EFFLUENT ON THE GROWTH OF TWO MARINE MICROALGAE

A growing global trend is the use of microalgae for the treatment of industrial effluents due to their capacity to consume contaminants, sequester carbon, and provide biomass for high-value products. Thalassiosira sp. and Chaetoceros gracilis, two marine microalgae, are the subjects of this study, which seeks to ascertain the effect of brewery effluent on their growth. The test microalgae were grown in seven culture vessels which were in triplicates and different concentrations; control (without effluent), 5, 10, 15, 20, 25, and 30% of brewery effluent. On a visible spectrophotometer, optical density at 750 nm was used to quantify growth responses, and several physicochemical variables were studied at the start and end using standard methods. Using Microsoft Excel 2010 and the social sciences statistical tool SPSS20, descriptive statistics, inferential (one way analysis of variance) ANOVA repeated measures, paired t-tests, and Tukey tests were performed. The findings revealed a significant difference in Thalassiosira sp. and Chaetoceros gracilis with growth response (p < 0.05). The growth of Thalassiosira sp. was stimulated by different concentrations of brewery effluent, Tukey test showed that 20, 25 and 30 % concentrations had higher mean differences, followed by 15 and 10% concentrations while, there was no mean difference between the control and 5% concentration. While the results for Thalassiosira sp. showed that, 25 and 30 % concentrations had higher mean differences, followed by 10, 15 and 20% concentrations.  There was no mean difference between the control and 5% concentration. The results of physicochemical variables indicated that only TOC and COD of brewery effluent fell at lower concentrations and stayed constant at higher concentraions, a decrease in temperature was seen across all concentrations. Thalassiosira sp. had more stimulatory effect than Chaetoceros gracilis making it a better option in the bioremediation of brewery wastewater when applied in higher concentrations.