Biochemical methane potential (BMP) of solid organic substrates: evaluation of anaerobic biodegradability using data from an international interlaboratory study Raposo, F.; Fernandez-Cegri

No abstract

Effect of trace element supplementation on the mesophilic anaerobic digestion of foodwaste in batch trials: the influence of inoculum origin. Biochemical Engineering Journal, in press, AbstractBatch anaerobic trials using a source-separated food waste as a substrate with inoculums of different origins were carried out under mesophilic conditions. Reactions were operated both with and without trace element (Co, Mo, Ni, Se, W) supplementation. Supplementation with trace metals had either neutral or slightly negative effects with inoculums originating from reactors with a high background level of metals, such as those for the co-digestion of biowaste and waste activated sludge. For inoculums from reactors treating food waste only, which inherently contain low levels of trace metals, supplementation with these metals increased methane production. In particular, Mo concentrations in the range of 3-12 mg per kg dry matter and Se concentrations of 10 mg per kg dry matter increased methane production to as high as 30-40%. Supplementation with a metal mixture (Co, Mo, Ni, Se and W) increased the methane production to the range 45-65% for inoculums with low background concentrations of trace metals. These findings may have an important impact in the commercial production of methane from food waste.

The paper presents the results of a pilot- and full-scale experimental campaign on the anaerobic co-digestion of waste activated sludge and biowaste both in mesophilic and thermophilic conditions. The study demonstrated the possibility to increase the specific biogas production from 0.34 to 0.49 m3/kgTVS and the gas production rate from 0.53 to 0.78 m3per m3 of reactor per day changing the reactor temperature from the mesophilic (37 °C) to the thermophilic (55 °C) range. The experimental work was carried out at pilot-scale, and the results match the full-scale behaviour. Ammonia nitrogen recycled from the anaerobic digestion section to the wastewater treatment plant accounted for about 4% of the total nitrogen loading. Digestate characteristics in terms of biological stability and heavy metals content suggested the opportunity of a short time post-aerobic stabilisation, leading to a high quality compost product

The optimization of a two-phase thermophilic anaerobic process treating biowaste for hydrogen and methane production was carried out at pilot scale using two stirred reactors (CSTRs) and without any physical/chemical pre-treatment of inoculum. During the experiment the hydrogen production at low hydraulic retention time (3d) was tested, both with and without reject water recirculation and at two organic loading rate (16 and 21 kgTVS/m3 d). The better yields were obtained with recirculation where the pH reached an optimal value (5.5) thanks to the buffering capacity of the recycle stream. The specific gas production of the first reactor was 51 l/kgVS(fed) and H2 content in biogas 37%. The mixture of gas obtained from the two reactors met the standards for the biohythane mix only when lower loading rate were applied to the first reactor, with a composition of 6.7% H2, 40.1% CO2 and 52.3% CH4 the overall SGP being 0.78 m3/kgVS(fed).