Effect of temperature on biohydrogen and biomethane production using a biochemical potential test with different mixtures of sewage sludge, vinasse and poultry manure

Abstract

A two-stage anaerobic co-digestion system has been proposed, comprising a first acidogenic stage at different temperatures, where biohydrogen is obtained; and a second mesophilic methanogenic stage where biomethane is obtained. The objective of this research was to evaluate the biochemical hydrogen potentials (BHP) at different temperature ranges, and their effect on the biochemical methane potentials subsequently carried out with the effluents from the BHP, in batch trials. Also, to evaluate the effect of adding a third co-substrate (poultry manure) to the mixture of sewage sludge and wine vinasse.For the BHP tests, temperatures of 35°, 55° and 70 °C were tested in mixtures of sewage sludge:vinasse (50:50) and sewage sludge:vinasse:poultry manure (49.5:49.5:1). It was found that the addition of poultry manure and a thermophilic temperature of 55 °C was ideal for biohydrogen generation with the highest recorded yield of 27.1mLH2/gVS.In the BMP trials consisting of effluent from the BHP and programmed at 35 °C, it was found that the effluent from the hyperthermophilic BHP trials (70 °C) generated more biogas and had a higher methane yield (117.36 mLCH4/gVS), and that this yield was higher for the sewage sludge and vinasse mixture alone. This proportion also had the highest percentage of VS removal (45.74%). The Modified Gompertz model was the best fit to the experimental data, with R2 > 0.983 in all cases.The search for the most suitable temperature ranges for the production of H2 and CH4 is necessary in order to be able to efficiently realise this technology on a larger scale.