RESUMEN
This study aims to assess composting efficiency and quality of compost through the study of the parameters of the Catalan Waste Agency (ARC) data-base by developing indicators useful for industrial sector. The study includes 17 composting plants for an 8-years period (2010-2017), the quantities of materials treated and generated in these plants: biowaste, yard trimmings, refuse and compost, as well as chemical characterization of compost: moisture, total organic matter, organic nitrogen, pH, electrical conductivity, self-heating test, pollutants and ammonium. Plant were sorted into 4 size classes depending on size capacity and into 4 technologies employed during thermophilic phase. Different indicators were developed related to improper fraction content, yard trimmings ratio, mass losses, compost production, refuse generation and plant saturation. The main average results indicate that improper fraction is 10%, process losses 68%, refuse generated 25% and saturation 79%. Differences were observed in size and technology; for instance, smaller plants presented lower improper content, refuse and saturation and higher losses while plants with turned windrows during decomposition presented higher improper, yard trimmings ratio and plants with vessel technology showed lower losses and higher saturation. Also, the compost quality is higher if the plant saturation and improper fraction are below 90% and 7%, respectively. The indicators were useful to assess the process and were related to the compost quality obtained.
