Unplanted sludge drying beds are shallow filters filled with sand and gravel with an under-drain at

the bottom to collect leachate. Sludge is discharged onto the surface for dewatering (Figure 7.1). The

drying process in a drying bed is based on drainage of liquid through the sand and gravel to the bottom

of the bed, and evaporation of water from the surface of the sludge to the air. The design as well as the

operation of the drying bed is fairly straightforward, provided the sludge loading rate is well selected

and the inlet points for depositing the sludge onto the bed are properly designed. Depending on the

faecal sludge (FS) characteristics, a variable fraction of approximately 50-80% of the sludge volume

drains off as a liquid (or leachate), which needs to be collected and treated prior to discharge (Tilley

et al., 2014). After reaching the desired dryness, the sludge is removed from the bed manually or

mechanically. Further processing for stabilization and pathogen reduction may be required depending

on the intended end-use option. When considering the installation of a drying bed, the ease of operation

and low cost needs to be considered against the relatively large footprint and odor potential.

fairly good

Content was at its best

But i was cheated on not getting a certificate

I am not sophisticated enough to buy this certificate

bad course