| Term | Definition |
|---|
| flocculation | Precipitation of suspended colloids |
| indicator organism | An organism that can signal the existence of others. For example e.coli can indicate that the water is contaminated with fecal waste. |
| coliform bacteria | Gram negative, no spore forming, aerobic, or facultative anaerobic bacteria that ferment lactose and produce acid and gas. Large amounts of coliform bacteria indicate that the water is unsafe to drink. |
| multiple-tube fermentation method | One of three ways to test for coliform bacteria. Three stages: presumptive test, confirmed test, and the completed test. |
| primary treatment | Physical means are used. |
| secondary treatment | Biological means . Trickling filter system sprays sewage bed of rock covered by aerobic bacteria In activated sludge system the effluent is constantly agitated, aerated, and added to sludge |
| tertiary treatment | Chemical and physical means are used to further purify water. |
| sludge digesters | Sludge from both primary and secondary treatments can be pumped into sludge digesters. Anaerobic bacteria digest sludge to simple organic molecules, CO2 and methane. Methane used for power |
| nitrogen fixation | reduction of atmospheric nitrogen to ammonia. Accomplished by certain free-living aerobes and anarobes, mainly by rhizobium |
| Rhizobium | bacteria that accumulate around legume roots and become swarmer cells that invade root cells to become bacteroids |
| Nitrogenase | in bacteroids, catalyzes nitrogen fixation reactions |
| nitrification | conversion of ammonia to nitrites and nitrates |
| water cycle | Recycles water. Precipitation -> intake by animals, plants -> transpiration |
| carbon cycle | Carbon from CO2 ->photsynthesis, chemosynthesis -> ->carbon compounds can be depositated in peat, coal, and pol and released during burning |
| nitrogenase | Reducing agent that supplies hyrdogen, as well as energy from ATP. Needed by nitrofen fixing bacteria. |
| sulfur cycle | movement of sulfur through ecosystem. Sulfur in protein ->hydrogen sulfide ->oxidized to sulfate -> |
| humus | nonliving organic matter |
| eutrophication | Abundant nutrient enrichment of water leads to excessive growth of algae. High BOD leads to O2 depletion, more dead matter. |
| biodegradation | Decomposition of humanmade materials by microbial activity. |
| ecology | Study of relationships between organisms and their environments. |
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