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The lake retention time for a body of water with the volume 2,000 m 3 (71,000 cu ft) and the exit flow of 100 m 3 /h (3,500 cu ft/h) is 20 hours.. Lake retention time (also called the residence time of lake water, or the water age or flushing time) is a calculated quantity expressing the mean time that water (or some dissolved substance) spends in a particular lake.
The residence time of a fluid parcel is the total time that the parcel has spent inside a control volume (e.g.: a chemical reactor, a lake, a human body).The residence time of a set of parcels is quantified in terms of the frequency distribution of the residence time in the set, which is known as residence time distribution (RTD), or in terms of its average, known as mean residence time.
Sludge volume index. Sludge Volume Index (SVI) is a process control parameter used to describe the settling characteristics of sludge in the aeration tank of an activated sludge process. [1] It was introduced by Mohlman in 1934 and has become one of the standard measures of the physical characteristics of activated sludge processes.
The acre-foot is a non- SI unit of volume equal to about 1,233 m 3 commonly used in the United States in reference to large-scale water resources, such as reservoirs, aqueducts, canals, sewer flow capacity, irrigation water, [1] and river flows. An acre-foot equals approximately an eight-lane swimming pool, 82 ft (25 m) long, 52 ft (16 m) wide ...
Retention basin. A retention basin, sometimes called a retention pond, wet detention basin, or storm water management pond (SWMP), is an artificial pond with vegetation around the perimeter and a permanent pool of water in its design. [1][2][3] It is used to manage stormwater runoff, for protection against flooding, for erosion control, and to ...
Waste stabilization pond. Waste stabilization ponds (WSPs or stabilization ponds or waste stabilization lagoons) are ponds designed and built for wastewater treatment to reduce the organic content and remove pathogens from wastewater. They are man-made depressions confined by earthen structures.
The runoff curve number (also called a curve number or simply CN) is an empirical parameter used in hydrology for predicting direct runoff or infiltration from rainfall excess. [1] The curve number method was developed by the USDA Natural Resources Conservation Service, which was formerly called the Soil Conservation Service or SCS — the ...
Facultative lagoon (polishing pond) providing tertiary treatment after a constructed wetland in Hamburg-Allermöhe, Germany. Overflow from the facultative lagoon may be routed through one or more polishing ponds supporting lower populations of anaerobic micro-organisms and a higher proportion of aerobic organisms adapted to survival in lower concentrations of organic material.