Sustainable Management of Wastewater Sludge Through Composting with Effective Microorganisms: Enhancing the Growth of Tecoma stans

The mismanagement of sewage sludge generated by wastewater treatment plants poses significant environmental and health risks, necessitating the exploration of sustainable alternatives for its reuse in forestry production. This study aims to assess the impact of sewage sludge stabilization and composting, utilizing effective microorganisms (EM), on the growth performance of Tecoma stans. A completely randomized experimental design was implemented in two phases. In the first phase, four treatments were tested with 12 kg of mixture in each: Treatment 1 (T1) (100% sludge with EM), Treatment 2 (T2) (75% sludge and 25% organic waste with EM), Treatment 3 (T3) (50% sludge and 50% organic waste with EM), and Treatment 4 (T4) (25% sludge and 75% organic waste with EM). The second phase involved testing five composite substrates, mixing agricultural soil with compost derived from each treatment and a control substrate, for the cultivation of Tecoma stans seedlings. Each substrate was tested with 20 experimental units, containing 15 seedlings per unit, totaling 300 seedlings. T3 demonstrated superior results in the first phase, containing 34.78% organic matter, 1.39% nitrogen, a carbon/nitrogen (C/N) ratio of 14.7, and a pH of 7.4, adhering to Chilean, Food and Agriculture Organization (FAO), and Mexican standards. In the second phase, T3 exhibited enhanced seedling growth, with an optimal nitrogen concentration and a Dickson quality index (DQI) of 0.768. The findings suggest that composting sewage sludge with organic residues in equal proportions and inoculating with EM produces mature, high-quality compost that meets international standards for forestry applications. This approach offers a sustainable solution for wastewater sludge management, promoting environmental restoration and supporting local forestry development.