Chapter 5 Flashcards
buried, watertight receptacles designed and constructed to receive wastewater from the structure to be served
SEPTIC TANKS
separates solids from the liquid, provides limited digestion of organic matter, stores solids, and allows the clarified liquid to discharge
SEPTIC TANKS
Substances lighter than water(oil, grease, fats) float to the top, where they form a scum layer.
Scum
The”sinkable” solids(soil, grit, bones, unconsumed food particles) settle to the bottom of the tank and form a sludge layer. Anaerobic bacteria works
Sludge
The clarified wastewater is left over after the scum has floated to the top and the sludge has settled to the bottom. It flows through the septic tank outlet into the drain field.
Effluent
the liquid volume in the clear space between the scum and sludge layers.
Effective volume
time the water spends in the tank, on its way from the inlet to the outlet. - function of the effective volume and the daily household wastewater flowrate
Retention time
A common design rule is for a tank to provide a minimum retention time of at least how many hours, during which one-half to two-thirds of the tank volume is taken up by sludge and scum
24 hours
Under ordinary conditions (i.e., with routine maintenance pumping) a tank should be able to provide how many days of retention time?
2-3 days
typically long, narrow trenches or channels to promote the occurrence of plug flow conditions
Constructed Wetlands
typically 1-m deep basin which is sealed with clay or some other form of
lining to prevent percolation into groundwater
Constructed Wetlands
filled with soil in which reeds are then planted.
Constructed Wetlands
can significantly remove BOD, TSS, nitrogen and phosphorus, as well as
metals, trace organics and pathogens
Constructed Wetlands
mosquito control and plant harvesting are the two main operational considerations
Constructed Wetlands
septic tank, a primary settling basin, or an anaerobic reactor commonly precedes what for sewage treatment?
Constructed Wetlands
