Treatment Processes and Organisms
Algae are chlorophyll-bearing plants that are distinguished from other chlorophyllous plants by their modes of sexual reproduction. In wastewater treatment systems, algae grow on the nutrients in the water and get energy from sunlight. The cyanobacteria of wastewater treatment systems can often be found on clarifier walls and trickling filters where they are exposed to sunlight. Ciliates, in particular, have been considered indicators of a good treatment process. More research on community structure and quality of treatment processes is necessary. Exposure of raw sewage to treatment processes shortens the survival time of the parasites. Parasites of humans and animals are different from many other sewage organisms, in the sense that they are not part of an active community of organisms interacting with the sewage and other organisms, but rather, stages that just exist in the sewage as resistant forms, usually as eggs or cysts.