Effect of Initial pH on Sulphate and Phosphate Uptake from Wastewater by Selected Bacterial and Fungal Species

Abstract

This study was aimed at investigating the effect of pH on sulphate and phosphate uptake from wastewater by selected bacterial and fungal species. A total of four each of bacterial and fungal isolates were used under shaking flasks conditions. The wastewater was supplemented with sodium acetate to serve as external carbon source at a concentration of 5 g/L. Immediately after inoculation with the respective isolates and at 24 h intervals, for the next 96 h, aliquot wastewater samples were taken from each flask for the estimation of total phosphate and sulphate in the wastewater, using standard procedures. The results revealed remarkable sulphate removal at pH 12. Apart from the Klebsiellasp. which showed high phosphate removal at pH 6, none of the isolates showed high phosphate removal at the different pH ranges. From an initial concentration of 480.22 mg/L, sulphate levels in the wastewater inoculated with the respective isolates were observed to decrease after 24 h incubation to 256.23 mg/L, 271.23 mg/L, 234.30 mg/L and 254.77 mg/L, in the presence of the Aspergillusniger, Aspergillusflavus, Fusarium and Absidiaspecies, respectively. For bacterial isolates, concentrations of sulphate after 24 h incubation were 290.85 mg/L, 218.14 mg/L, 278.16 mg/L and 298.93 mg/L, in the presence of the Pseudomonas, Klebsiella, Lysinibacillus and Staphylococcus species, respectively. The study was able to reveal the optimum pH for sulphate and phosphate uptake by the test microbial species.