Abstract:
Wastewater treatment and post-treatment drying techniques play a crucial role on the
fertilizer value of biosolids. The aim of this study was to investigate: the nitrogen
fertilizer value of biosolids from selected biosolid treatment and post treatment
dewatering techniques (a) and the effect of drying depth and time on the nitrogen content
of biosolid (b). To achieve the first aim, laboratory nitrogen mineralization study was
conducted using thermally-hydrolysed-biosolid, activated-biosolid, and
anaerobically-digested-biosolids. To achieve the second aim five drying depths were
tested (5, 10, 15, 20 and 25 cm). Nitrogen release per tonne biosolid applied was highest
for activated (24 kg), and lowest for anaerobically-digested-biosolid (6 kg). Highest total
nitrogen was reported for 10 cm drying depth (3.63%) (4 weeks) and lowest for 25 cm
(2.64%) (8 weeks). Selection of appropriate biosolid treatment and dewatering technique
is key to improve fertilizer value of biosolids.
