This document defines protozoa as one-celled animals found worldwide in most habitats. It classifies protozoa into four main groups - Sarcodina, Mastigophora, Ciliophora, and Sporozoa - and provides examples of free-living and parasitic protozoa in each group. It describes the structures of protozoa, including pseudopodia, flagella, and cilia used for locomotion. It also discusses the shapes of protozoa and their role in wastewater treatment through cropping and coating action to remove bacteria. Finally, it notes that reproduction is mainly asexual through binary fission but some undergo sexual reproduction.

1. Protozoa
‫يزيد‬‫سعيد‬‫الزهراني‬ : ‫عمل‬‫الطالب‬
‫أنس‬‫سراج‬‫دبلول‬ : ‫إشراف‬‫سعادة‬‫الدكتور‬
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2. Outline
Protozoa Definition.
Classification of Protozoa
Structures
Shapes
Protozoa usage in environmental engineering
Reproduction in protozoa

3. Protozoa Definition
• Protozoa are one-celled animals found worldwide in most habitats. Most species are free living, but all higher
animals are infected with one or more species of protozoa. Infections range from asymptomatic to life threatening,
depending on the species and strain of the parasite and the resistance of the host.

4. Classification of
Protozoa
Sarcodina
Motility is due to the streaming of ectoplasm, producing protoplasmic projections called pseudopodia (false
feet). Examples: Free-living form like Amoeba proteus* and parasitic form like Entamoeba histolytica*.
Mastigophora Locomotion is effected by one or more whip-like, thin structures called flagella. Examples: Free- living forms like
Euglena viridis*, Cercomonas longicauda*, Heteronema acus* and parasitic forms like Trichomonas vaginalis,
Trypanosoma gambiense*, Giardia lamblia*.
Ciliophora Locomotion is carried out by means of short hair-like projections called cilia, whose synchronous beating
propels the organisms. Examples: Free-living forms like Paramecium caudatum*, Stentor polymorpha*,
Vorticella campanula* and parasitic form like Balantidium coli*.
Sporozoa Unlike the above three classless of protozoa, members of the class sporozoa do not have locomotor organelles
in their mature stage; however, immature forms exhibit some type of movement. All the members of this group
are parasites.

5. Structure of Protozoa
Protozoa are microscopic unicellular
eukaryotes that have a relatively
complex internal structure and carry
out complex metabolic activities. Some
protozoa have structures for propulsion
or other types of movement.
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6. Shapes of Protozoa
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7. Protozoa in the Wastewater Treatment Process
• most protozoa are free-living in soil and water and enter the activated sludge process through inflow
and infiltration. The number of protozoa within the activated sludge process or mixed liquor varies
greatly by process and operational conditions, especially hydraulic and organic loadings. The relative
abundance of protozoa may be less than 100 per milliliter or greater than 100,000 per milliliter.
• Protozoa, especially ciliated protozoa, perform several beneficial roles in wastewater treatment.
These roles include cropping action, coating action, and recycling of mineral nutrients.
• Bacteria are the primary food source for protozoa, and the consumption of suspended or dispersed
bacteria by protozoa is referred to as "cropping" action. Cropping action removes many dispersed
bacteria from the bulk solution.

8. Reproduction
in protozoa
• Binary fission, the most common form of
reproduction, is asexual; multiple asexual division
occurs in some forms. Both sexual and asexual
reproduction occur in the Apicomplexa.
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9. references
• https://drive.uqu.edu.sa/_/asdablool/files/environmental_microbiology/lec8.pdf
• https://www.ncbi.nlm.nih.gov/books/NBK8325/
• https://www.yourarticlelibrary.com/micro-biology/protozoa-definition-characteristics-
classification-and-types/26683
• https://water.mecc.edu/courses/ENV108/lesson6_2.htm

10. This Photo by Unknown author is licensed under CC BY.