Evaluation of the Addition of Wood Ash to Control the pH of Substrates in Municipal Biowaste Composting

AbstractThis study evaluates the addition of wood ashes (WA) for controlling the pH of substrates in municipal biowaste (MBW) composting. Three combinations in wet weight percent (w/w) of MBW and WA were tested: i) BC1: 2% WA and 98% MBW; ii) BC2: 4% WA and 96% MBW; and iii) BC3: 8% WA and 92% MBW. Each combination was compared with a control (100% MBW) called B1, B2 and B3 respectively. The experiment was conducted to pilot scale, with piles of 510kg. The results indicate that the addition of WA improved the pH level and nutrients for the composting process; however, it had not substantial benefit in the process (start of the thermophilic phase and the behavior of the substrate degradation rate). Furthermore, a higher presence of salts and phytotoxic compounds in the product was observed. This could limit the product use for agricultural activities