Reduction of phytotoxicity of organic compost

The Brazilian legislation for organic compost type A allows a maximum of 50% moisture for commercialization. Thus, the use of dryers may be an alternative to reach this percentage. The objective of this work was to evaluate the effect of the continuous dryer on physical-chemical, microbiological and phytotoxicological characteristics of organic compost. The compost was elaborated with sludge from a poultry and pork slaughtering treatment plant and sawdust. Continuous counter-flow cylindrical dryer was used, with collections before, during and after the dryer. The results were submitted to the Duncan test (p <0.05), presenting reduction of parameters such as humidity, organic carbon and exchangeable acidity. In addition, the compost after the dryer had a higher concentration of mineral matter, N, S, Zn, Cu and Mn (p <0.05), highlighting its agronomic potential. Parameters in the compost as pH, P, K, mesophilic and thermophilic microorganisms were not influenced (p <0.05) before and after the dryer. Finally, the passage of the compound through the dryer promoted a decrease in phytotoxicity (p <0.05), favoring the development of the bioindicators used. It is concluded that the use of the dryer can be a promising alternative for the valorization of the organic compost.