Enhancement of Food Production — BIOLOGY STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYEnhancement of Food Production5 Marks
Question
Microorganisms in sewage.
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Answer
Sewage contains pathogenic bacteria, viruses, fungi, protozoa which cause dysentery, cholera, typhoid, polio and infectious hepatitis, etc. It also contains nematodes and algae.
Their number and type of microorganisms in sewage depends on the composition and source of sewage.
Millions of bacteria per ml may be present in raw untreated sewage.
Bacteria in sewage include coliforms, fecal Streptococci, anaerobic spore forming bacilli and other bacteria found in the intestinal tract of humans.
The sewage also contains soil bacteria.
During sewage decomposition, initially aerobic and facultative anaerobic organisms predominate which are followed by strict anaerobic especially methogenic bacteria that produce methane $(CH_4)$ and $CO_2.$
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