The use of fly ash as conditioner for dewatering of biological sludges in drying beds

In this paper the conditioning of the secondary sludge by adding fly ash from thermal power plant of Ptolemaida (Greece) for dewatering in drying beds is examined.

The results of the experimental procedure that has been followed in a pilot unit are very encouraging and show that the addition of the fly ash in concentration of 6 % of the weight of the total suspended solids of the sludge in the entrance of the drying bed increases the filterability at the level of 95.4 % and the retention of the solids at the level of 110.5 %. Consequently the method employed allows the decrease of the area of the drying bed at the level of 100 % approximately.