The effects of pH and temperature on phosphate and nitrate uptake by wastewater protozoa

Abstract

The objective of this study was to ascertain the effects of pH and temperature on nutrient uptake efficiency of 3 wastewater protozoan isolates (Aspidisca (A), Trachelophyllum (B) and Peranema (C))
that have previously been screened for nutrient uptake ability. The study was carried out in shake flask at pH 5, 6, 7, 8 and 9 and incubation temperatures of 25, 30 and 35oC for 96 h. The results revealed optimum pH ranges for the uptake of phosphate and nitrate to be 7 to 9 and 5 to 7, respectively. Maximum nutrient uptake was found to occur at 25oC with phosphate concentration decreasing from
64.74 to 10.21 mg/l, 63.09 to 8.54 mg/l and 64.47 to 6.36 mg/l, for isolates ‘A’, ‘B’ and ‘C’, respectively. Also, nitrate concentration was found to decrease from 24.71 to 4.91 mg/l for isolate ‘A’, 24.47 to 11.15 mg/l for isolate ‘B’, and 24.58 to 15.00 mg/l for isolate ‘C’ at the same temperature. An increase in COD was observed in mixed liquor inoculated with the test isolates. The study has been able to give an
insight into the optimum temperature and pH for phosphate and nitrate uptake by the isolates.