The potential presence of toxic compounds in the digestate obtained from the anaerobic digestion of biodegradable waste restricts its application as a biofertilizer for soil conditioning and plant growth enhancement. The aim of this study was to assess digestate quality in terms of plant nutrient composition by evaluating the effects of activated carbon supplementation, inoculum source, and total solids content in the anaerobic digestion medium. The anaerobic digestion of food waste was conducted over a 60-day period at 25 °C in a 2.5 L bioreactor. The results demonstrated that inoculum diversity significantly impacted the digestate composition, particularly the zinc nutrient, with a p-value of 0.0054. This suggests that microbial diversity influences the valorization of organic waste into biofertilizer. However, the effects of inoculum diversity on other nutrients, aside from zinc, were not significant due to substantial interaction effects. Furthermore, assessing the impact of activated carbon supplementation proved challenging, as it was analyzed as part of a subset of the other two factors. The results of the digestate composition analysis indicated that activated carbon supplementation exhibited some influence on nutrient composition, necessitating further research to elucidate its significance. The findings of this study may contribute to enhancing the quality of digestate as a biofertilizer.