The heros of the process are the peritrich ciliates, like this Vorticella. Primarily through their efforts, the coliform and other suspended bacteria are filtered out of the sewage in the activated sludge tank. If the rate of throughout is increased to a rate where the growth of peritrichs is insufficient to keep up, then the ciliates are removed and the quality of the effluent plummets. This image was provided by D. J. Patterson. Copyright: D. J. Patterson, image used under license.
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From the collection
Activated sludge - sewage treatment
|Description of Vorticella convallaria: Stalked, sessile peritrich ciliate; body 30-120 micrometres long, pedicle 100-500 micrometres. Bell-shaped, somewhat conical body, usually twice as long as it is broad; light in colour, often yellowish. Peristomial lip slightly rolled over. Pellicle with transverse ridges (annulations). Stalk relatively thick, containing spasmonemes that enable it to contract with extreme suddenness. The contracted stalk is helical. Macronucleus long, vermiform, often J-shaped. Found in large groups. Freshwater in stagnant conditions. |