The growing production of biowaste like food waste, vegetable waste, and animal manure results from the increased global population and economic growth and the lack of effective public policies for adequate management that encourage more sustainable practices such as nutrient recycling. Although applied to only 2% of the municipal solid waste in Brazil, composting and vermicomposting are attractive, low-cost, and effective biological ways to stabilize several types of biowastes and increase the circular economy through the use of organic compost. This study aimed to optimize the composting and vermicomposting process by adding effective microorganisms (EM) and evaluate the vermicompost performance in the production of vegetable seedlings. The pre-composting windrow was operated for 23 days. It was constructed with 120 kg of organic waste (58%, 31%, 9%, and 2% food waste (FW), cattle manure (CM), grass clippings (GC), and tree brunches (TB), respectively). Six treatments were tested in the vermicomposting with different EM doses, consisting of a commercial compost (CC) and 0 (D0), 3 (D3), 4 (D4), 5 (D5), and 6 (D6) mL EM L− 1 substrate. The pre-composting windrow balanced the pH values, making them closer to neutrality. It also slightly reduced carbon and maintained nitrogen contents in the waste between 2.4 and 2.6% (dry matter). Vermicomposting with EM addition concentrated nutrients, with best TKN results close to 3.1% (dry matter) with the addition of 3 mL EM L− 1 substrate. In addition to the highest nitrogen content, treatment D3 presented higher total phosphorous and Dickson quality index (DQI) values than the control treatment, showing the potential to add EM to generate a higher maturity and agronomic relevance compost.
