Influence of the composition of the initial mixtures on the chemical composition, physicochemical properties and humic-like substances content of composts.

The influence of the proportion of C- and N-rich raw materials (initial C/N ratio) and bulking agent on the chemical functional groups composition, humic-like substances (HS-like) content and physicochemical properties of composts was assessed. To achieve these goals, seven initial mixtures (BA1-6 and C1) of dog food (N-rich raw material) were composted with wheat flour (C-rich raw material). Composts were analyzed in terms of chemical functional groups, physicochemical, maturity and stability parameters.

Recovery of humic-like susbtances from low quality composts.

The quality of four commercial composts produced from poultry litter and municipal solid wastes was assessed based on their physic-chemical, stability and maturity parameters. These properties varied among the analysed composts; it was found that electric conductivity, heavy metals content and maturity were the parameters that limited the composts quality. Therefore, the feasibility of using them to obtain liquid fertilisers rich in humic-like substances (HS) was assessed.

Co-composting of poultry manure with low quantities of carbon-rich materials.

To study the feasibility of co-composting poultry manure with low quantities of high-value, carbon-rich materials experiments to characterize three pilot-scale piles were carried out. The piles comprised poultry manure (pile 1), poultry manure and straw (pile 2) and poultry manure and sawdust (pile 3), using wood chips as bulking agent. Pile 1 presented the highest losses of organic matter and nitrogen contents (> or = 92.