ABSTRACT
Conventional and microwave extraction, using water as solvent, were tested for the recovery of nutrients from mixed municipal waste compost (MMWC). The effect of compost to water ratio (10, 20, 40 %w/V), extraction time (6, 24, 48 h) and temperature (30, 45 and 60° C) has been studied for conventional extraction and particle size, temperature (60, 80 and 100° C) and solid/liquid ratio (10, 20, 40 %w/V) for microwave extraction. Maximum TOC and TN concentrations of 16.8 g/L TOC and 2.3 g/L TN were obtained for optimal conventional extraction (40% w/V, 45°C and 24h). Regarding microwave extraction, the optimum was reached operating for 2.5 min with 40% w/V, 80°C and milled MMWC (dp <0.5 mm) obtaining TOC and TN concentrations of 11.9 g/L and 2.5 g/L, respectively. The microwave extraction provides a very attractive and green alternative for the nutrients extraction of MMWC with an important reduction of the extracting time.
