VIII. Design Protocol

When designing a treatment facility using an ABR, the following design considerations must be made.

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Flow rate $($Q$)$:

The flow for sewage treatment plants are based on the design population and commercial and industrial activity $(9).$ Historical data should be used to find existing flow information. A typical rule for estimating domestic wastewater flows is $380$ L$/$cap$/$day$.$ The flow estimates for a location should show peak, minimum and average flow rates.

Hydraulic Retention Time $($HRT$)$ and Solid Retention Time $($SRT or ${}_x)$:

In typical suspended solids reactors without recycle, the SRT has to be equal to the HRT $(9).$ The minimum HRT in these reactors is about ten days at $35C.$ One major advantage of an ABR is that the bacteria grow on fixed surfaces within the reactor, allowing very high SRTs$.$ This also allows the HRT and SRT to be separated, which significantly reduce reactor volume. HRT can be calculated as shown below.

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A typical HRT value for an ABR is about $1$ohours $(3,4,18,$ and $19).$

The solids retention time can be described by the mass of sludge in the reactor divided by the mass removal rate of sludge from the reactor $(9).$

${}_x=V\frac{x_v}{Q_w}{x}_w$

Qw Volumetric flow rate of waste solids from system

Xw VSS concentration in Qw

$V,$ Volume of reactor

$xv,$ Average concentration of VSS in reactor

Volume of Reactor $($V$)$:

The volume of the reactor can be determined based on the flow rate and a set HRT or the HRT can be determined based on a set reactor volume, depending on the application $(9).$

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This volume calculation describes the minimum volume needed in order for the tank to handle the incoming flow of wastewater. A factor of safety should be applied when designing a wastewater treatment plant to avoid flooding of the system. This, help me pre phrase this