Start-up and operation of continuous stirred-tank reactor for biohydrogen production from restaurant organic solid waste

• The organic loading rate have an influence on the hydrogen production in a CSTR.
• The increase of OLR results in a decrease of COD and proteins removal and H2 yield.
• The H2 production rate and H2 yield showed a behavior of a quadratic polynomial function.

The hydrogen production from a variety of substrates, including organic solid waste (OSW), has been studied at different organic loading rate (OLR), finding different behavior on the hydrogen production rate (HPR) that can be related to the particular waste characteristics and particular operational conditions. The objective of this study was to evaluate the start-up and operation of a continuous stirred-tank reactor (CSTR) to generate hydrogen from food waste applying different OLR in order to determine the operational conditions to obtain the maximal HPR. Three OLR, controlled via the influent flow rate, were studied: 19, 38 and 57 gVS/Lreactor/d. It was found that the OLR has an influence on the hydrogen production in the CSTR. The increase of OLR results in a decrease of COD removal, protein removal, and hydrogen yield (YH2). The highest HPR (19.8 mmol H2/Lreactor/d) and YH2 (0.6 mmol H2/gVS) were obtained at the OLR of 37.1 and 19.8 gVS/Lreactor/d, respectively. The H2 percentage in biogas had variations between 25 and 55% independently of the OLR. The VS and COD removal efficiencies were 51 ± 9% and 27 ± 9% respectively. Acetic acid was the principal VFA produced during the CSTR operation.