Microbial fertilizer from co-composted sludge using mishimax-50 system

Sewage sludge from municipal and dairy wastewater treatment in Vietnam poses environmental challenges due to landfill overload and groundwater contamination. This study investigated co-composted sludge-derived microbial fertilizer (MK50) as a sustainable agricultural alternative. Sludge was co-composted with wood chips using mixing and thermal stabilization, producing MK50 with heavy metal levels below Vietnam’s safety thresholds. Microbial analysis revealed high densities of phosphate-solubilizing (1.45 × 10^6 CFU/g) and cellulose-degrading (2.16 × 10^6 CFU/g) bacteria, surpassing commercial biofertilizers. Field trials on water spinach and purple amaranth showed MK50 yields (3.33 kg/m² and 5.00 kg/m², respectively) comparable to or better than commercial fertilizers, with improved morphometric parameters (p < 0.05). However, MK50’s low nitrogen content (2.08%) led to less vibrant foliage. These results suggest MK50’s potential for sustainable agriculture by valorizing sludge through microbial activity, though further research is needed to optimize nutrient profiles and long-term efficacy.