Bio-hydrogen and bio-methane potentials of skim latex serum in batch thermophilic two-stage anaerobic digestion

• First report on bio-hydrogen and bio-methane potentials of skim latex serum (SLS).
• The bio-hydrogen potential of 1.57 L/L SLS was obtained.
• The bio-methane potential of 12.2 L/L SLS was also generated.
• The maximum energy production from SLS was 12 kJ/g VS.
• Two-stage anaerobic digestion could efficiently remove organic content from SLS.

Anaerobic digestion by two-stage process, containing hydrogen-producing (acidogenic) first stage and methanogenic second stage, has been proposed to degrade substrates which are difficult to be treated by single stage anaerobic digestion process. This research was aimed to evaluate the bio-hydrogen and the bio-methane potentials (BHP and BMP) of skim latex serum (SLS) by using sequential batch hydrogen and methane cultivations at thermophilic conditions (55 °C) and with initial SLS concentrations of 37.5–75.0% (v/v). The maximal 1.57 L H2/L SLS for BHP and 12.2 L CH4/L SLS for BMP were both achieved with 60% (v/v) SLS. The dominant hydrogen-producing bacteria in the H2 batch reactor were Thermoanaerobacterium sp. and Clostrdium sp. Meanwhile, the CH4 batch reactor was dominated by the methanogens Methanosarcina mazei and Methanothermobacter defluvii. The results demonstrate that SLS can be degraded by conversion to form hydrogen and methane, waste treatment and bioenergy production are thus combined.