Studies on the agricultural utilization of phosphate from incinerated sewage sludge and meat & bone meal

The key objectives of this research work were to assess chemical changes in element composition through incineration, to investigate the P availability of different waste materials and their ashes, to assess changes in micronutrients and heavy metals, and to study the impact of "in situ¿ digestion on nutrient availability. This was realized in two sets of greenhouse experiments using grass (Lolium multiflorum L.) as a test crop. The goal of the first experiment was to compare the effect of original and ash materials of sewage sludge (SS/SSA), bone meal (BM/BMA) and meat and bone meal (MBM/MBMA) on the availability of P and heavy metals. The goal of the second experiment was to investigate the effect "in situ¿ digestion with elemental S and Thiobacillus inoculation on P mobilization and release of heavy metals. The mineral fertilizers triple superphosphate (TSP) and hyperphos (HP) were used as reference (fertilizers).