Technical and economic feasibility of additives in situ in anaerobic digestion of cattle manure

Abstract

Anaerobic digestion (AD) is a notorious technique for the disposal of manure from the cattle industry, however, improvement methods are sought for this process. Thus, the objective was to evaluate the effect of direct application of bioremediation and commercial starch on AD of dairy cattle manure (DCM) with a sense of meaning the effect of the bioremediation. Semi-continuous tubular digesters with a useful volume of 60L were used, with hydraulic retention time of 30 days, at room temperature. Four treatments were treated with four repetitions distributed in a completely randomized design, in a factorial scheme 22 represented by the factors starch (with and without application) and bioremediation (with and without application). Based on the results obtained from treatments with the isolation of the bioremediator, they were defined in real scenarios in order to assess the economic viability of the application of the bioremediator. The application of starch and the main bioremediator the highest averages of the potentials of biogas production and reductions in solids (p <0.05) when compared to the treatment without their applications, however, for a specific production of methane per kg of total solids (m3kg-1TSadded) and depreciated volatiles (m3kg-1VSadded) the application of the bioremediation has better results (p <0.05). The combined use of the factors did not enhance the bioremediation effect and there were no large sets of nutrient tools without biofertilizer. Of the adopted scenarios, only the treatment without the application of the exclusive bioremediator would be financially attractive. Although DCM's AD was optimized with the application of the bioremediator, the technical viability, the use of the additive did not indicate economic viability.