Biological hydrogen production using co-culture versus mono-culture system

Abstract

In coming years, the generation of organic wastes will exceed 250 billion tonnes worldwide. The organic wastes offer plentiful source of readily available and inexpensive substrates for fermentative hydrogen production. A sustainable approach for hydrogen production from various methods, such as photo-, dark fermentation and sequential two-stage has significant advantages to complement traditional process. During hydrogen fermentation, defined, well-characterized and composite microorganisms are studied. Substantial research efforts have been carried out to increase hydrogen production by using co-culture system, which offers advantage of increased H₂ yield and production rate in comparison with mono-culture. The concept of co-culture system is a simple step of mixing different microbial strains for improving the individual properties that other strain lacks. Co-culture system is cost-effective, which potentially eliminates pretreatment step and avoids the use of expensive reducing agent. By eliminating these two steps, the overall process cost can be reduced without negotiating the hydrogen yield. The co-culture system directly hydrolyses complex organic substrates into fermentable sugar with 94.1% improved yield in comparison with mono-culture. Co-culture offers various advantages, example, reduction in lag phase, resistance to environmental fluctuations and provides stability with uninterrupted hydrogen production rate, which is eight times in comparison with mono-culture. The co-culture system of hydrogen production is also an alternative effluent treatment method with 60% reduction in the chemical oxygen demand level and can be easily integrated into a pilot scale to achieve continuous H₂ production. The elaboration on co-culture system suggests a huge potential of hydrogen production using complex organic wastes with viable application towards industrialization.

Keywords:

• co-culture
• dark fermentation
• hydrogen
• mono-culture
• organic wastes
• photo-fermentation

Acknowledgements

The views or opinions expressed in this article are those of the authors.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are sincerely thankful to the Natural Sciences and Engineering Research Council of Canada [Discovery Grant 355254], Le Centre de recherche industrielle du Québec (CRIQ), MAPAQ [No. 809051], Ministère des Relations internationales du Québec (coopération Paraná-Québec 2010–2011).