PREPARATION AND COMPOSTING OF PEAT AND DEWATERED SEWAGE-SLUDGE

Dried dewatered sludges have considerable potential as constituents of growing media.
Such sludges are easy to handle and free of pathogens.
However, they are extremely hydrophobic.

The water repellant nature of these sludges can be overcome by composting with saturated sphagnum peat.
During composting, the temperature of heaps of dried sludge and sphagnum peat rose to around 60°C within five days, and gradually declined over a period of 30–40 days.
Ammoniacal-N concentrations in heaps rose gradually over this period, but declined following turning of heaps.
Nitrate-N concentrations rose following turning of heaps, indicating increased activity of nitrifying bacteria.
During composting, heaps were colonised by mesophilic and thermophilic bacteria and fungi.
Thermophilic fungi such as Mucor pusillus, Aspergillus fumigatus and Humicola spp were present in high numbers (10⁶–10⁷ propagules per g oven dry weight) when heaps reached 50–60°C and declined as temperatures fell to ambient.

International Symposium on Substrates in Horticulture other than Soils In Situ

W.R. Carlile, M.A. Macfarlane, E. Sweetland

https://doi.org/10.17660/ActaHortic.1984.150.53