Comparing methods for protozoa removal in activated sludge

One of the key technological parameters for highly efficient wastewater treatment methods is bacterial mortality. Protozoa are known for feeding on free floating bacteria, that initiate floc formation and participate in putrefaction process. Reliable protozoa removal methods are still unavailable which have negative impact on the development of the current knowledge in this field. The aim of this study was to find the most effective method which removes most of protozoa present in the activated sludge without affecting the overall treatment efficiency. Seven possible methods of removing protozoa were tested by analysing several technological parameters. The evaluation of the presented methods was based on the efficiency of protozoa removal, as well as on the effects of the removal methods on autotrophic, heterotrophic and endogenous oxygen uptake. Mechanical disintegration proved to be the most effective and reliable method. It allowed for the complete removal of protozoa without the inhibition or inactivation of bacteria. The comprehensive and complete data obtained from the conducted research will be used to improve existing wastewater treatment processes with regards to both the technological point of view and mathematical modelling.

Automated summary

Bacterial mortality is a key parameter for highly efficient wastewater treatment methods. Protozoa are known to feed on bacteria and can affect the efficiency of treatment processes. This study aimed to find an effective method to remove protozoa from activated sludge without impacting overall treatment efficiency.