Protozoa enumeration via microscope – some remarks on methodology

Abstract

For proper enumeration of protozoa in activated sludge good methodology is required. In this paper we present some remarks on microscopic methodology of protozoa enumeration. This remarks concern number of repetitions from one sample required to obtain good statistical results as well as influence of sample aeration on number of found protozoa. Presented data shows that at last 10 repetitions are required from each sample to obtain low average confidence interval. Lower number of repetitions leads to sharp increase in average confidence interval and loss of statistical significance while higher number does not decrease average confidence interval substantially. As measurements lasts for few hours lack of sample’s aeration during measurement leads to detection of lower by 27% number of protozoa.