Dark fermentation

Dark fermentation is the fermentative conversion of organic substrate to biohydrogen. It is a complex process manifested by diverse group of bacteria by a series of biochemical reactions involving three steps similar to anaerobic conversion. Dark fermentation differs from photofermentation because it proceeds without the presence of light.

Fermentative/hydrolytic microorganisms hydrolyze complex organic polymers to monomers which are further converted to a mixture of lower molecular weight organic acids and alcohols by obligatory producing acidogenic bacteria.

Utilization of wastewater as a potential substrate for biohydrogen production has been drawing considerable interest in recent years especially in the dark fermentation process. Industrial wastewater as a fermentative substrate for H₂ production addresses most of the criteria required for substrate selection viz., availability, cost and biodegradability (Angenent, et al., 2004; Kapdan and Kargi, 2006). Chemical wastewater (Venkata Mohan, et al., 2007a,b), cattle wastewater (Tang, et al., 2008), dairy process wastewater (Venkata Mohan, et al. 2007c), starch hydrolysate wastewater (Chen, et al., 2008) and designed synthetic wastewater (Venkata Mohan, et al., 2007a,2008b) have been reported to produce biohydrogen apart from wastewater treatment from dark fermentation processes using selectively enriched mixed cultures under acidophilic conditions. Various wastewaters viz., paper mill wastewater (Idania, et al., 2005), starch effluent (Zhang, et al., 2003), food processing wastewater (Shin et al., 2004, van Ginkel, et al., 2005), domestic wastewater (Shin, et al., 2004, 2008e), rice winery wastewater (Yu et al., 2002), distillery and molasses based wastewater (Ren, et al., 2007, Venkata Mohan, et al., 2008a), wheat straw wastes (Fan, et al., 2006) and palm oil mill wastewater (Vijayaraghavan and Ahmed, 2006) were also studied as fermentable substrates for H₂ production along with wastewater treatment. Using wastewater as a fermentable substrate facilitates both wastewater treatment apart from H₂ production. The efficiency of the dark fermentative H₂ production process was found to depend on pre-treatment of the mixed consortia used as a biocatalyst, operating pH, and organic loading rate apart from wastewater characteristics (Venkata Mohan, et al., 2007d,2008c,d, Vijaya Bhaskar, et al., 2008d).

In spite of its advantages, the main challenge observed with fermentative H₂ production processes are relatively low energy conversion efficiency from the organic source. Typical H₂ yields range from 1 to 2 mol of H₂/mol of glucose, which results in 80-90% of the initial COD remaining in the wastewater in the form of various volatile organic acids (VFAs) and solvents, such as acetic, propionic, and butyric acids and ethanol . Even under optimal conditions about 60-70% of the original organic matter remains in solution. Bioaugmentation with selectively enriched acidogenic consortia to enhance H₂ production was also reported (Venkata Mohan, et al., 2007b). Generation and accumulation of soluble acid metabolites causes a sharp drop in the system pH and inhibits the H₂ production process. Usage of unutilized carbon sources present in acidogenic process for additional biogas production sustains the practical applicability of the process. One way to utilize/recover the remaining organic matter in a usable form is to produce additional H₂ by terminal integration of photo-fermentative processes of H₂ production (Venkata Mohan, et al., 2008e) and methane by integrating acidogenic processes to terminal methanogenic processes.

See also

• Biogas
• Biohydrogen
• Biological hydrogen production (Algae)
• Biomass
• Electrohydrogenesis
• Fermentation (biochemistry)
• Microbial fuel cell

References

• Angenent, L.T., Karim, K., Al-Dahhan, M.H., Wrenn, B.A., Domíguez-Espinosa, R., 2004. Production of bioenergy and biochemicals from industrial and agricultural wastewater. “Trends in Biotechnology” 22, 477-85.
• Chen, S.-D., Lee, K.-S., Lo, Y.-C., Chen, W.-M., Wu, J.-F., Lin, C.-Y., Chang, J.-S.,2008, Batch and continuous biohydrogen production from starch hydrolysate by Clostridium species. “Int J Hydrogen Energy” 33, 1803-1812.
• Dabrock, B., Bahl, H., Gottschalk, G., 1992. Parameters affecting solvent production by Clostridium pasteurianum, “Appl Environ Microbiol”, 58, 1233-1239.
• Das, D., Veziroglu, T.N., 2001. Hydrogen production by biological process: a survey of literature. “Int J Hydrogen Energy” 26, 13-28.
• Das, D., 2008, International workshop on biohydrogen production technology (IWBT 2008),7–9 February 2008, IIT Kharapgur. “Int J Hydrogen Energy” 33, 2627-2628.
• Fan, Y.T, Zhang, Y.H., Zhang, S.F., Hou, H-W., Ren, B-Z., 2006. Efficient conversion of wheat straw wastes into biohydrogen gas by cow dung compost. “Biores Technol” 97, 500-505.
• Ferchichi, M., Crabbe, E., Gwang-Hoon, G., Hintz, W., Almadidy, A., 2005. Influence of initial pH on hydrogen production from cheese whey. “J Biotechnol” 120, 402-409.
• Idania, V.V., Richard, S., Derek, R., Noemi, R.S., Hector, M.P.V., 2005. Hydrogen generation via anaerobic fermentation of paper mill wastes. “Biores Technol” 96, 1907-1913.
• Kapdan, I. K., Kargi, F., 2006. Bio-hydrogen production from waste materials, “Enzyme Microb Technol” 38, 569–582.
• Kim, J., Park, C., Kim, T-H., Lee, M., Kim, S., Kim, S., Seung-Wook., Lee, J., 2003. Effects of various pretreatments for enhanced anaerobic digestion with waste activated sludge. “J. Biosci. Bioeng” 95, 271-275.
• Kraemer, J.T., Bagley, D.M., 2007. Improving the yield from fermentative hydrogen production. “Biotechnol Let” 29, 685–695.
• Logan, B.E., 2004. Feature article: biologically extracting energy from wastewater: Biohydrogen production and microbial fuel cells. “Environ Sci Technol” 38,160A-167A.
• Logan, B.E., Oh, S.E., van Ginkel, S., Kim, I.S., 2002. Biological hydrogen production measured in batch anaerobic respirometers. “Environ Sci Technol” 36, 2530-2535.
• Ren, N.Q., Chua, H., Chan, S.Y., Tsang, Y.F., Wang, Y.J., Sin, N., 2007. Assessing optimal fermentation type for bio-hydrogen production in continuous flow acidogenic reactors, “Biores Technol” 98, 1774-1780.
• Roy Chowdhury, S., Cox, D., Levandowsky, M., 1988. Production of hydrogen by microbial fermentation. “Int J Hydrogen Energy” 13, 407-410.
• Shin, H.S., Youn, J.H., Kim, S.H., 2004. Hydrogen production from food waste in anaerobic mesophilic and thermophilic acidogenesis. “Int J Hydrogen Energy” 29, 1355-1363.
• Sparling, R., Risbey, D., Poggi-Varaldo, H.M., 1997. Hydrogen production from inhibited anaerobic composters. “Int J Hydrogen Energy” 22, 563–566.
• Tang, G., Huang, J., Sun, Z., Tang, Q., Yan, C., Liu, G., 2008. Biohydrogen production from cattle wastewater by enriched anaerobic mixed consortia: Influence of fermentation temperature and pH. “J Biosci Bioengng.”, 106, 80-7
• Valdez-Vazquez, I., Rıos-Leal, E., Munoz-Paez, K.M., Carmona-Martınez, A., Poggi-Varaldo, H.M., 2006. Effect of inhibition treatment, type of Inocula, and incubation temperature on batch H2 production from organic solid waste. “Biotechnol Bioeng” 95, 342-349.
• van Ginkel, S.W., Oh, S.E., Logan. B. E., 2005. Biohydrogen gas production from food processing and domestic wastewaters. “Int. J. Hydrogen Energy” 30, 1535-1542.
• Venkata Mohan, S., Vijaya Bhaskar, Y., Sarm, P.N., 2007a. Biohydrogen production from chemical wastewater treatment by selectively enriched anaerobic mixed consortia in biofilm configured reactor operated in periodic discontinuous batch mode. “Water Res” 41, 2652-2664.
• Venkata Mohan, S., Mohanakrishna G., Veer Raghuvulu S., Sarma, P.N., 2007b. Enhancing biohydrogen production from chemical wastewater treatment in anaerobic sequencing batch biofilm reactor (AnSBBR) by bioaugmenting with selectively enriched kanamycin resistant anaerobic mixed consortia. “Int J Hydrogen Energy” 32, 3284–3292.
• Venkata Mohan, S., Lalit Babu, V., Sarma, P.N., 2007c. Anaerobic biohydrogen production from dairy wastewater treatment in sequencing batch reactor (AnSBR): Effect of organic loading rate. “Enzyme and Microbial Technology” 41(4), 506-515.
• Venkata Mohan, S., Bhaskar, Y.B., Krishna, T.M., Chandrasekhara Rao N., Lalit Babu V., Sarma, P.N., 2007d. Biohydrogen production from chemical wastewater as substrate by selectively enriched anaerobic mixed consortia: Influence of fermentation pH and substrate composition. “Int J Hydrogen Energy”, 32, 2286– 2295.
• Venkata Mohan, S., Mohanakrishna, G., Ramanaiah, S.V, Sarma, P.N., 2008a. Simultaneous biohydrogen production and wastewater treatment in biofilm configured anaerobic periodic discontinuous batch reactor using distillery wastewater. “Int J Hydrogen Energy”33(2), 550-558.
• Venkata Mohan, S., Mohanakrishna, G., Ramanaiah, S.V, Sarma, P.N., 2008b. Integration of acidogenic and methanogenic processes for simultaneous production of biohydrogen and methane from wastewater treatment. “Int J Hydrogen Energy” 33, 2156–2166.
• Venkata Mohan ,S., Lalit Babu, V., Sarma, P.N., 2008c. Effect of various pre-treatment methods on anaerobic mixed microflora to enhance biohydrogen production utilizing dairy wastewater as substrate. “Biores Technol” 99, 59-67.
• Venkata Mohan, S., Lalit Babu, V., Srikanth, S., Sarma, P.N., 2008d. Bio-electrochemical behavior of fermentative hydrogen production process with the function of feeding pH. “Int J Hydrogen Energy” doi:10.1016/j.ijhydene.2008.05.073.
• Venkata Mohan, S., Srikanth, S., Dinakar, P., Sarma, P.N., 2008e. Photo-biological hydrogen production by the adopted mixed culture: Data enveloping analysis. “Int J Hydrogen Energy” 33(2), 559-569.
• Venkata Mohan, S., Mohanakrishna,G., Reddy, S.S., Raju, B.D., Rama Rao, K.S., Sarma, P,N., 2008f.Self-immobilization of acidogenic mixed consortia on mesoporous material (SBA-15) and activated carbon to enhance fermentative hydrogen production. “Int J Hydrogen Energy” doi:10.1016/j.ijhydene.2008.07.096.
• Vijaya Bhaskar, Y., Venkata Mohan S, Sarma, P.N., 2008. Effect of substrate loading rate of chemical wastewater on fermentative biohydrogen production in biofilm configured sequencing batch reactor. “Biores Technol” 99, 6941–6948.
• Vijayaraghavan, K., Ahmad, D., Biohydrogen generation from palm oil mill effluent using anaerobic contact filter. “Int J Hydrogen Energy” 31, 1284-1291.
• Yu, H., Zhu, Z., Hu, W., Zhang, H., 2002. Hydrogen production from rice winery wastewater in an upflow anaerobic reactor by using mixed anaerobic cultures, “Int J Hydrogen Energy” 27, 1359-1365.
• Zhang, T., Liu, H., Fang, H.H.P., 2003. Biohydrogen production from starch in wastewater under thermophilic condition. “J Environ Manag” 69, 149-156.
• Zhu, H., Beland, M., 2006, Evaluation of alternative methods of preparing hydrogen producing seeds from digested wastewater sludge. “Int J Hydrogen Energy” 31, 1980-1988.

External links

• Bio-hydrogen production from wastewater