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BOD test bottles at the laboratory of a wastewater treatment plant. Biochemical oxygen demand (also known as BOD or biological oxygen demand) is an analytical parameter representing the amount of dissolved oxygen (DO) consumed by aerobic bacteria growing on the organic material present in a water sample at a specific temperature over a specific time period.
The model describes how dissolved oxygen (DO) decreases in a river or stream along a certain distance by degradation of biochemical oxygen demand (BOD). The equation was derived by H. W. Streeter, a sanitary engineer, and Earle B. Phelps, a consultant for the U.S. Public Health Service, in 1925, based on field data from the Ohio River. The ...
An advantage of the plug flow model is that no part of the solution of the problem can be perpetuated "upstream". This allows one to calculate the exact solution to the differential equation knowing only the initial conditions. No further iteration is required. Each "plug" can be solved independently provided the previous plug's state is known.
A value frequently used in the international literature for PE, which was based on a German publication, is 54 gram of BOD (Biochemical oxygen demand) per person (or per capita or per inhabitant) per day. [1]: 65 [2] This has been adopted by many countries for design purposes but other values are also in use. For example, a commonly used ...
The continuous stirred-tank reactor (CSTR), also known as vat-or backmix reactor, mixed flow reactor (MFR), or a continuous-flow stirred-tank reactor (CFSTR), is a common model for a chemical reactor in chemical engineering and environmental engineering. A CSTR often refers to a model used to estimate the key unit operation variables when using ...
FW = Formula weight of the oxidizable compound in the sample, RMO = Ratio of the # of moles of oxygen to # of moles of oxidizable compound in their reaction to CO 2, water, and ammonia. For example, if a sample has 500 Wppm (Weight Parts per Million) of phenol: C 6 H 5 OH + 7O 2 → 6CO 2 + 3H 2 O COD = (500/94)·7·16*2 = 1192 Wppm
For example, if the feed is a saturated liquid, q = 1 and the slope of the q-line is infinite (drawn as a vertical line). As another example, if the feed is saturated vapor, q = 0 and the slope of the q-line is 0 (a horizontal line). [2] The typical McCabe–Thiele diagram in Figure 1 uses a q-line representing a partially vaporized feed.
Darcy's law is an equation that describes the flow of a fluid through a porous medium and through a Hele-Shaw cell.The law was formulated by Henry Darcy based on results of experiments [1] on the flow of water through beds of sand, forming the basis of hydrogeology, a branch of earth sciences.