Co-Pelletization of Dairy Manure Compost and Fishmeal for Soil Amendment and Environmental Management

Abstract

Studies on improving utilization, transportation, and storage of animal manure nutrients are critical to mitigating potential adverse environmental impacts of excess manure nutrients produced in regions with high concentrations of animal production. This study investigated the potential of fishmeal for improving manure compost quality and the effects of co-pelleting both products on the pellets’ properties. The percentage pre-pelleting blending ratio of fishmeal ranged from 0–20%. Based on previous studies, pellets were produced at a moisture content of 21% (w.b.), with 6-mm, 8-mm, and 10-mm dies. The effects of fishmeal blending were evaluated against the pellets’ unit and bulk densities, recovery, durability, and nutrients (total-N and P2O5) concentration of the resulting pellets. Scanning Electron Microscopy (SEM) images were used to assess the effect of fishmeal blending on pellets’ porosity and surface smoothness. For the three die sizes, results showed positive correlations between fishmeal content and unit density (r≥0.93 for both 6-mm and 8-mm dies), total-N (r≥0.98), and P2O5 (r≥0.98). Inverse correlations were observed between blending ratio and pellets durability (r≤ -0.98), and pellet length (r≤ -0.91 for the 6-mm and 8-mm dies). The effects of fishmeal addition on pellets recovery and diameter were not significant, while effects of die size also varied with different quality criteria. Overall, the study revealed nutrient value and transportability were improved when: (1) compost was blended with small proportions of fishmeal, and (2) smaller dies were used.

Keywords: Pelletization, Blending, Pellets recovery, Nutrients concentration, Pellets durability.