Influence of pile turning frequency for moisture control in municipal biowaste composting

Substrates of biowaste composting are characterized by high moisture contents that affects the aerobic transformation of organic matter. A strategy for moisture control on the process is achieved by increase of turning the pile to a certain frequency. This study assesses the influence of this strategy for the initial moisture control in biowaste composting. Two types of pilot-scale piles were assessed with different turn frequencies during the first four weeks of the process. Pile A was turned at least two times per week and pile B six turns per week. Results show that the increase on the turn frequency was effective for reducing initial moisture of the substrates. A high degradation rate of organic matter was achieved. This was reflected in a shorter duration of the mesophilic, termophilic and cooling phases (20 % less time). Furthermore, the sanitation temperatures were kept for seven additional days. The increase on the turn frequency influences the nutrient content and COT decrease and hence the agronomic value of the product. In addition, this increase favored the reduction of phytotoxic substances allowing a higher germination index and less electric conductivity.