Results and discussion Biogas production

According to Buswell's equation, conversion of proteins, lipids and Simeprevir produce 496mLCH4/gVS, 1014mLCH4/gVS and 415mLCH4/gVS respectively [25]. Based on the I. galbana   composition, the theoretical methane yield is 612mLCH4/gVS and the biodegradability is 55.2%. This is a high value according to conversion degrees obtained under practical conditions for highly particulate or structural substrates, and can be explained by the microalgae species characteristics [25]. Additionally, it is fairly well known that the microalgae cell wall determines the potential conversion into biogas; I. galbana cells have been described as small size cells, with a lack of a cell wall which facilitates anaerobic digestion [11] and [31]. Furthermore, the change from a high saline to a non saline environment favours microalgae disintegration [30].
In the case of substrate mixture productions were between sludge and microalgae production. Their digestion reached 394 ± 14 mLBiogas/gVS, 392 ± 4 mLBiogas/gVS and 330 ± 6 mLBiogas/gVS for 25%, 50% and 75% microalgae respectively. It is noticeable that the higher the amount of VS from microalgae, the lower the biogas production. Hence, substrate mixing does not increase the biogas yield of the substrates separately digested as was expected.