Anaerobic Digester: Equipment Tab

Variable Definitions, Ranges and Default Values

The following table shows the meaning of the variables appearing in this tab, as well as their default values and their generally acceptable range. Note that due to the manner by which the variables are used by the sizing and costing equations, the range of acceptable values may be further reduced.

Variable	Default Value	Range

◙ Volume The total vessel volume.	0.0 L	Positive
◙ Max Volume The maximum volume that a unit of this type is available for purchase in the market.	15,000,000 L	Positive

Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output

Sizing: Design Mode

In Design Mode, the user specifies the Maximum Vessel Volume and the system computes the Number of Units and the Vessel Volume. In the Volumes tab of the operation interface, the user specifies the hydraulic residence time (t_R) and the working to vessel volume ratio. The working (liquid) volume (V_w) and the vessel volume (V) are calculated using the following equations:

eq. (B.1)

eq. (B.2)

Where F is the feed volumetric flowrate. If the calculated vessel volume exceeds its maximum possible value (specified through the Equipment tab), the system assumes multiple, identical units operating in parallel with a total vessel volume equal to the calculated.

Sizing: Rating Mode

In Rating Mode, the user specifies the Number of Units, the Volume and the basin’s depth and length to width ratio.

Costing

The equipment purchase cost is based on the total vessel volume. By default it is calculated by the program’s built-in model for an Aeration Basin, with a minimum costing volume of 200 m³.

For more information on this equipment, see Anaerobic Digester or Anoxic Reactor.

For information on the left-hand side variables and options, see Equipment Data Dialog: Equipment tab.