lect 21 Flashcards
what happens in the primary treatment of wastewater?
aerating the system: air bubble will attach to oils and organics and will increase the buoyancy (they float to top)
-main compounds of air are O2 and N2, which are both nonpolar: meaning they have nigh affinity for nonpolar compounds (oil, organics)
what are the two main sources for water sewage treatment?
-aqueous municipal wastes
-other aqueous wastes from industry and agriculture
why is sewage treatment necessary? what should the final treated water be free of?
why is it necessary?
-to meet regulations
-so that aqueous effluent does not have unacceptable adverse effects on receiving waters
final treated water should be free of:
-organic and most inorganic compounds
-pathogens
-excessive BOD (recall: BOD is used as a measure of oxygen-demanding substances)
what is the primary settling of sewage treatment?
purpose: removal of solids
done by filtration and settling
-water is slowed once entering tanks, allowing settling to occur
-saskatoon has a grit and screen building (removes heavy particles)
-solids go to landfill
-effluent usually has a high BOD
-advanced primary treatment: use of coagulants to remove very small particles that contribute to BOD
what is the secondary treatment of sewage water?
what is the trickling filter?
what is the activated sludge process?
what is the graph of activated sludge process?
what are the kinetics of bacterial growth?
what are the factors affecting bacterial metabolism?
what is done with sewage sludge and what is it?
what is an anaerobic digester?
what are the problems with sludge?
what is tertiary treatment?
how do we remove phosphates?
what are chemical precipitants for phosphate and their products?
what are natural water purification processes?
what is green water?
what is the graph of a system for water reuse?
