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Protozoan diversity in the activated sludge at Benha waste-water treatment plant, Kalubeyia  province, Egypt

Mansour Galal

Zoology Department, Faculty of Science, Menofyia University

ABSTRACT

           Protozoa play an important role in the efficient functioning of the waste water treatment plants. The presence of certain types of protozoa produces final effluent of good quality to be used in the  irrigation of cultivated and  urbanized lands. The main objective of this study was to identify various types of protozoa at different stages of the wastewater  treatment plant. Two different phyla of protozoa (Sarcomastigophora and Ciliophora) were represented in  all the examined samples of the wastewater treatment plant at Benha. Fifteen  protozoan orders were detected within these two phyla in the mixed-liquor of the sludge. Five of them were belonging to subphylum Mastigophora and three were referred to subphylum Sarcodina. These eight orders comprised 17 genera and/or species, while phylum Ciliophora was represented by seven orders including 59 species.

It was observed that  subphylum Sarcodina contained six genera belonging to two classes; Rhizopodea and Actinopodea. On the other hand, subphylum Mastigophora included two classes; Phytomastigophorea comprising nine genera/ species and Zoomastigophorea having two genera. Phylum Ciliophora was represented by four of its subphyla namely Holotrichia, Peritrichia, Spirotrichia and Suctoria which were collected from almost all samples during the studying period. The numerical densities of most protozoan organisms in the present study were higher than those of the potable water treatment plant which could be referred mainly to the high trophic level of the former one. Ciliates feed mostly on bacteria and not on dissolved organic material, bacteria and flagellates compete for dissolved nutrients, while ciliates compete with other ciliates and rotifers for bacteria. The presence of ciliates indicated a good effluent of the sludge as they dominate after the floc has been formed and after most of the organic nutrients have been removed.

Key words : Bacteria, Protozoa,  Waste-water treatment.