Home and vermicomposting as sustainable options for biowaste management

Home composting (also known as backyard composting) presents some potential benefits for the industrial treatment of the organic fraction of municipal solid waste or biowaste. Home composting avoids the collection of biowaste, reduces the impurities present in the waste being treated and, consequently, in the resulting compost, and theoretically decreases the material and energy needs of the process. However, self-composting requires a composting bin and pruning waste as bulking material as well as space in a garden or on a roof that is not always available. An alternative for the self-management of biowaste is vermicomposting, which requires less space and no bulking material. Both the home composting and vermicomposting methods were studied over an eight-month period to determine the quality of the compost produced, the capacity of the methodology and the resulting gaseous emissions. The treatment capacity of the composters used in this work was determined on a weekly basis. The vermicomposter had a treatment capacity of 50 g biowaste per L, whereas the home composter had a treatment capacity of 16 g biowaste per L. The home composter required the addition of 6.3 g of bulking agent per L of composter. The quality of the final product, compost, was similar in both cases, with each batch of compost having low metal content and a high degree of stability, with Dynamic Respiration Indices of 0.43 and 0.89 mg O2 g−1 Organic Matter h−1 for compost and vermicompost, respectively. Gaseous emissions from home composters show the presence of 1.3 kg NH3 Mg−1 biowaste and 1.35 kg CH4 Mg−1 biowaste, values that are within the range reported in the literature for home and industrial composting, although N2O emissions, 1.16 kg Mg−1 biowaste, were higher. Gaseous emissions from the vermicomposters were lower than from the home composters: 3.33 × 10−3, 2.19 × 10−3 and 3.66 × 10−3 kg of pollutant Mg−1 biowaste for NH3, CH4 and volatile organic compounds, respectively. No odours were detected for either system. Home and vermicomposting can be considered suitable alternatives to divert a portion of the biowaste from the traditional waste-management system.