2006-11-20 03:27:32 · 3 answers · asked by Anonymous in Environment
The typical sewage treatment plant for domestic waste involves primary and secondary treatment. Primary treatment involves removing solids from the stream, while secondary treatment involves, to varying degrees, measures to neutralize water-borne contaminants and most importantly, pathogens. Tertiary treatment is usually referred to the process of bringing the water back to drinking-water grade.
The City of Arcata, California, along with the help of scientists at Humboldt State University, designed and built a "bio-dynamic" treatment plant. After a rather typical primary treatment, the sludge is used for bio-gas production. Secondary treatment is achieved through the use of a series of ponds which are also used as municipal green space and wildlife habitat. Although this system removes almost all pollutants through biological action, chlorine must still be used to ensure the removal of viral disease. The result is tertiary treatment at a cost much lower than traditional methods. There are additional benefits. These ponds are literally the pride of the city and on sunny days hundreds of people flock to the marsh to enjoy the outdoors. To read more, go to the web site listed below.
2006-11-20 06:48:18 · answer #1 · answered by gordon B 3 · 0⤊ 0⤋
Chlorine is used to treat effluents to kill bacteria.Chelating agents are added to precipitate some elements. Alum compounds are added to settle particles.
2006-11-20 11:37:50 · answer #2 · answered by science teacher 7 · 0⤊ 0⤋
Let the workers win a few.
2006-11-20 15:44:43 · answer #3 · answered by JOHNNIE B 7 · 0⤊ 0⤋