ABSTRACT
The study examined the various growth responses of cultured Chlorella vulgaris and Scenedesmus obliqus to varying concentrations of a characterized raw brewery effluent. Both microalgae were cultured in Chu’s No. 10 modified medium supplemented with varying concentrations of the brewery effluent (0% (control), 5%, 10%, 25%, 50%, 75% and 100%). The growth responses of the cultivated microalgae were measured at 2-day intervals for 14 days using a visible spectrophotometer at a wavelength of 750nm. Physicochemical attributes of the raw effluent, percentage inhibition values for the cultured microalgae as well as oxidative stress protein assays were also determined using appropriate methods. For growth response of cultivated C. vulgaris, an overall uniform growth increase was observed from day 6 to day 14 for specimens cultured on several treatments with peak growth at 100% for day 14. For growth response of cultured S. obliquus, maximum growth response was recorded for algae cultivated in 50% and 100% treatments and a consistent growth pattern was observed from day 0 to day 2 for all the treatments. The lowest SOD, glutathione peroxidase, catalase and total protein content for C. vulgaris cultured on the different treatments were; -4. 511277, 0.00000, - 0.473684 and 0.19 while maximal values for these parameters were; 0.4177109, 0.00875, - 0.052632 and 1.14. Minimal SOD, glutathione peroxidase, catalase and total protein content for S. obliquus were -0.01817, 0.00700, -0.094733 and 0.19 while maximal values were; 10.025063, 0.02100, 0 and 0.95. The pH and TDS values of the effluent were; 8.16 and 204.00mg/l respectively. The growth response recorded for C. vulgaris was higher than that of S. obliquus at the same concentrations of effluents, which was indicative that higher concentrations of nutrients were required by S. obliquus to simulate the same amount of growth that a lower concentration would stimulate with respect to C. vulgaris. It is recommended that further studies that would focus on the growth effects of treated brewery effluents on other freshwater algae species should be conducted.
