{"id":3734,"date":"2024-09-10T15:38:47","date_gmt":"2024-09-10T10:08:47","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=3734"},"modified":"2025-08-11T16:25:54","modified_gmt":"2025-08-11T10:55:54","slug":"population-equivalent","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ce\/engineering-hydrology\/population-equivalent","title":{"rendered":"Population Equivalent"},"content":{"rendered":"

Average standard BOD of domestic sewage is 80 gms per person per day. The number of person which produce the amount of BOD at the rate of 80 gms per person per day equal to that produced by industrial sewage<\/a> is called population equivalent of industrial sewage. Industrial wastewater are generally compared with per capita normal domestic wastewater, so as to rationally charge the industries for the population caused by them. The strength of the industrial sewage is, thus worked out as below.<\/p>\n

\"Population<\/p>\n

RELATIVE STABILITY<\/h2>\n

The term relative stability of a sewage effluent may be defined as the ratio of oxygen available in the effluent (as D.O., nitrite or nitrate) to the total oxygen required to satisfy its first stage BOD demand. It is expressed as percentage of the total oxygen required, and can be expressed by the equation.<\/p>\n

Relative stability = S = 100 {1-(0.794)t20<\/sup>}<\/p>\n

S = 100 {1-(0.630)t37<\/sup>}<\/p>\n

where, S = The relative stability, t(20)<\/sub> and t(37)<\/sub> represent the time in days for a sewage sample to decolourise a standard volume of methylene blue solution, when incubated at 20\u00b0 or 37\u00b0C respectively.<\/p>\n

The decolourisation caused by the enzymes produced by anaerobic bacteria, infact, is an indication of the available oxygen in oxidising the unstable organic matter.<\/p>\n

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