The recalcitrant particulate structure of cattle manure limits hydrolysis during anaerobic digestion, thereby reducing methane productivity and renewable energy recovery in agricultural biogas systems. This study investigated pilot-scale hydrodynamic cavitation (HC) pretreatment of cattle manure followed by laboratory-scale batch anaerobic digestion, using an integrated Venturi-based cavitation reactor and a programmable logic controller–supervisory control and data acquisition (PLC–SCADA) process monitoring system. The approach combined mechanical pretreatment, HC and automated process monitoring to improve substrate conversion efficiency, digestion stability and overall process performance. Methane production kinetics were evaluated using the modified Gompertz model, while digestate nutrient composition and energy performance were also assessed. HC increased cumulative methane production from 234.9 ± 5.9 to 324.7 ± 7.0 mL g⁻¹ COD, corresponding to an increase of 38.2%, while cumulative biogas production increased from 397.6 ± 7.1 to 497.7 ± 6.5 mL g⁻¹ COD (25.2%). Peak daily methane production was higher in the cavitation-treated reactors, consistent with enhanced methane-production kinetics following HC pretreatment. Modified Gompertz modeling confirmed higher methane production potential (239.5 → 330.8 mL g⁻¹ COD) and maximum methane production rate (35.3 → 48.9 mL g⁻¹ COD d⁻¹), whereas the lag phase remained short in both treatments. HC also increased total nitrogen (N), phosphorus expressed as P₂O₅, and potassium expressed as K₂O contents in the digestate on a dry-weight basis. Relatively stable pH conditions were maintained throughout digestion, with lower pH variability observed in the HC-treated reactors. Energy analysis showed a positive incremental net energy balance, with an additional methane energy recovery of 42.97 kWh m⁻³, a specific additional electrical energy input of 19.0 kWh m⁻³, and an incremental net energy ratio (NER) of 2.26. Overall, the results show that HC can enhance methane production and methane-production kinetics and may support nutrient recycling while maintaining positive incremental energy performance. The integrated cavitation and PLC–SCADA system offers a promising approach for sustainable livestock waste management in organic farming systems.
As one of the food baskets in East Java Province, Ngawi Regency plays a strategic role in supporting regional and national food security. The local government has launched the Ngawi Go Organic 2030 program to transform the production system from conventional to organic agriculture. The provision of incentives under this program has not yet served as a lever for rice farmers to aggressively transition to organic agriculture. Only approximately 37% of the identified rice paddy area is currently under Sustainable Environmentally Friendly Agriculture (Pertanian Ramah Lingkungan Berkelanjutan, PRLB) implementation. This study aims to formulate an incentive redesign to enhance the capacity of rice farmers within the PRLB program in Ngawi Regency. The study employs a qualitative method using the Participatory Rural Appraisal (PRA) approach and in-depth interviews. Research informants included personnel from the Ngawi Regency Food Security and Agriculture Office, field agricultural extension workers, PRLB farmer groups, organic farming associations, and marketing institutions. The data were analysed using thematic analysis, while source and methodological triangulation were used to enhance data validity. The results indicate that government incentives have supported the implementation of PRLB; however, gaps remain in marketing, economic benefits, risk management, the use of environmentally friendly inputs, and farmer capacity building. The proposed incentive redesign includes financial and non-financial incentives supported by enhanced technical, managerial, institutional, and digital capacities for farmers. The integration of these components is expected to increase the adoption of PRLB, strengthen farmers’ competitiveness and income, and support environmental sustainability in Ngawi Regency.
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