Effect of hydrogen peroxide on radiofrequency-oxidation of dairy manure

A novel technology involving a combination of radiofrequency (RF) heating and hydrogen peroxide (H₂O₂) addition was used to treat dairy manure as a part of a manure management and resource recovery scheme; the process was to release nutrients and to disintegrate dairy manure for subsequent struvite crystallisation process and/or anaerobic digestion. The factors affecting the process, namely, H₂O₂ dosage, heating time and radiofrequency temperature, were studied using a surface response design methodology. The results indicated that solids disintegration efficiency in terms of soluble chemical oxidation demand concentration in the treated solution was in a range of 15–18% of total chemical oxygen demand. Very high volatile fatty acid concentrations were also produced. Orthophosphate (ortho-P) concentrations were in the range of 36–52% of total phosphorus in the treated solution. The optimal operating conditions for both solids disintegration and ortho-P release were predicted to be RF temperature of 83°C, holding time of 55–60 min and H₂O₂ dose of 1.7–1.8%.