Download Wastewater Microbes and Organisms

Wastewater Microbes and Organisms
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In nature and in a wastewater treatment plant, organisms are the key players in keeping our water clean.
About the following photographs
The following photographs provide a general sampling of the organisms involved in the cleansing process. Under a microscope, a
variety of organisms can be observed having different sizes, shapes, life cycles, mobility and roles. Identifying the various microbes
can be a challenging task.
Consider playing our game, micromatch, and see how well you can quickly identify the various organisms typically found in a drop of
wastewater.
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BACTERIAL FILAMENTS
Using a phase contrast microscope, living bacteria can be visualized quite well. Some are motile and may swim across the field of
view, while others may appear to vibrate or drift.
Rod-shaped, filamentous bacteria, shown here, have been referred to as "sewage fungi."
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PROTOZOA - Ameoba
Several groups of protozoa are representated in wastewater treatment plants. These include amoeba, stalked ciliates, crawler ciliates,
free swimmers and flagellates.
The primary role of protozoa is to clarify the effluent through predation on bacteria.
Amoeba come in two forms, shelled and without a shell. Here is a common shelled one, Arcella. The shell is composed of tiny sand
grains.
Here's a common Amoeba without a shell. The body shape changes with movement. They don't have cilia.
These are also common, don't have a shell, and are very tiny in comparison to the other types of Amoeba.
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PROTOZOA - STALKED CILIATES
Single stalk ciliate consume food via vorticellids, oral cilia that wind completely around the top of the cell. The stalk contains a
contractile, slightly sinuous filament that can rapidly coil up like a sping, pulling the cell body down.
Sheathed stalked ciliate secrete a lorica, an outer membrane that protects the ciliate.
Several types of colonial stalked ciliate commonly occur in wastewater treatment plants.
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PROTOZOA - Crawler Ciliates
These are two different crawler ciliates. They are called crawlers because they "crawl" over surfaces such activated sludge floc so
they can find bacteria to eat. They don't free-swim very well.
The side view of Euplotes shows the "setae" which act as their legs. Both Euplotes and Aspidisca are common in activated sludge
and their presence is desired as they indicate a well operating plant.
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PROTOZOA - Free Swimmers
These are two common free swimmers in activated sludge. They have cilia all over the body which allows them to freely swim
through the water. They feed on bacteria.
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PROTOZOA - Flagellates
This is one of the largest flagellates found in activated sludge...so you can imagine the difficulty of photographing the smaller ones!
This one, has a long flagella that extends out and one that lays down along the body. The flagella enables movement as well as the
ability to catch food by pulling bacteria down to it's "mouth" where the flagella attaches to the body.
There are two primary groups of flagellates. The Peranema belongs to the group which ingests its food. The other group of
flagellates is more like bacteria. They don't ingest whole food. They take in food that is already partially "digested."
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ROTIFERS
Both of these images are the same genus of rotifer and are the most common in activated sludge. Rotifers are multi-celled animals,
which draw in chunks of bacterial floc to feed on.
This type of rotifer is also fairly common and has a shell around it. Some rotifers have shells, some do not. The presence of rotifers in
activated sludge generally means a good, stable sludge with plenty of oxygen.
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WORMS - Aquatic Earthworms
Aquatic earthworms are very much like the earthworms in our yards, but live in an aquatic environment. Our earthworms in a yard
can't do this...as is obvious every time the ground gets saturated from rains. Worms come out in mass...much to the delight of Robins.
Aquatic earthworms have setae along the body which allows them to tunnel through the floc particles, ingesting chunks of bacterial
floc. They can be very common in old activated sludge.
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WORMS - Nematodes
Round worms (Nematodes) are also common in activated sludge. Unlike aquatic, they are not segmented and their intestines are
straight (earthworms have convoluted intestines like us). Round worms also feed on chunks of bacterial floc.
The round worms seen in wastewater treatment plants are "free living", that is, they are not parasites. Most people are familiar with
the intestinal round worms people and pets get as well as those that are plant parasites. Round worms do not have the setae like
earthworms and move through the substrate by whipping their body back and forth.