17.01.2015 Views

GPS-X Technical Reference

GPS-X Technical Reference

GPS-X Technical Reference

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Sand Filtration Models 270<br />

MASS BALANCE MODEL<br />

The massbalance model is based on empirical removal efficiency for suspended solids, BOD and<br />

TKN parameters. A `best' value is set for removal efficiency immediately after backwash. The<br />

removal efficiency decreases during the filter cycle time as the filter is fouled until the next<br />

backwash. The decrease in the removal efficiency is modelled with an exponential function:<br />

Equation 9.5<br />

where:<br />

out<br />

in<br />

= filter effluent component concentration (mg/L)<br />

= filter influent component concentration (mg/L)<br />

bestefficiency = best removal efficiency after backwash (%)<br />

foulingcoeff<br />

cycletime<br />

= fouling coefficient<br />

= time elapsed since last backwash (h)<br />

A minimum efficiency value for suspended solids removal is also defined as an operational<br />

parameter. This parameter does not affect removal computed by the model but warns the user<br />

that, once removal of solids gets below this minimum value, the filter is undergoing high<br />

headloss.<br />

Figure 9-2 – Operational Parameters Form – Massbalance Model<br />

<strong>GPS</strong>-X <strong>Technical</strong> <strong>Reference</strong>

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!