Synergistic Impact of Nanoscale Zero-Valent Iron in Anaerobic Co-digestion Treatment and Biogas Upgrading from the Organic Fraction of Municipal Solid Waste-Activated Sludge

Zero-valent iron dosages have an impact on the performance of anaerobic co-digestion of organic fraction of municipal solid waste and activated sludge. Diverse dosages of zero-valent Iron additives within the range of 15-90 mg NP-ZVI/g VS were investigated under mesophilic conditions and a pH reading of 6.0 to deduce their impact on the AD stability in the domain of hydrolysis and acidification percentages, pollutants' uptake, and biogas upgrading rate. It was found that the biogas production was relatively ameliorated with the additives of NP-ZVI at different dosages compared to the non-amended AD process. The results revealed that the threshold of 45 mg NP-ZVI/g VS dosage to a high organic fraction substrate has achieved the most distinguishing features in the AD performance, as distinct through improving the hydrolysis by a factor of 30.5%, acidification percentage by 43.7%, TCOD removal by 89%, methane yield by 18.4%, and biogas production approaches the figure 0.398 Nm(3)/kg VS with an increase by 36% compared to that of the control test. Whereas a high dosage of 90 mg NP-ZVI /g VS appealed to an acute inhibition on AD that should be avoided, due to the retrogression of methanogenic activity for an anaerobic environment with such additives of concentrated NP-ZVI. Generally, the cumulative biogas production patterns were fitted using a nonlinear least square regression technique. The biogas production of the investigated substrates was adequately predicted by the three-parametric modified Gompertz and logistic models. [GRAPHICS]