Biohydrogen is acknowledged to be environmentally benign and the most promising renewable energy resource and an ideal alternative to fossil fuels that doesn't contribute to the greenhouse. When properly harnessed, it can provide a safe, clean and unlimited supply of energy for all of the world's basic energy needs. Experts agree that an alternate source of energy to the world's limited supply of oil and natural gas is a national imperative. Making biohydrogen a viable and practical means of energy for wide-spread use requires much in the way of research and scientific exploration. The Fermentation Technology Laboratory research activities contribute to the growing role that advanced technologies play in addressing the nation's energy challenges. Our projects focus on maximization of hydrogen production by dark fermentation, photofermentation and biophotolysis of water; application of the generated biomass pre and post hydrogen production; customized reactor designing; scale up studies; and microbial fuel cells.
Microbial fuel cell
Microbial fuel cell (MFC) found promising for the treatment of various wastewaters. Research work mostly focused on the improvement of the performance of MFC, reduction of construction cost and expansion of the application scopes of MFC based technologies collectively known as bioelectrochemical systems. Low cost materials for the anode, cathode and membrane in MFCs were studied to increase the power generation using complex wastewater. MnCo2O4 in presence of polypyrrole (PPy) on carbon cloth cathode showed maximum power densities of 6.4 W m-3 using low cost KOH doped PVA-PDDA anion exchange membrane. MFCs were found suitable for the secondary stage treatment process by linking it with dark fermentation processes for the enhancement of overall energy recovery. Overall 33 % energy was recovered from the wastewater. Feasibility of power generation and hydrogen production in a microbial electrolysis cell were also studied using organic wastes like sewage sludge. The maximum hydrogen yield of 4.5 mmol H2 g-1CODreduced was obtained at 1.0 V. Microbial carbon capture cells (MCCs) with cyanobacteria as photo-biocathode was successfully demonstrated which is responsible for power generation, carbon dioxide sequestration and wastewater treatment. Recently, paper based micro-MFC for low power applications (such as biosensors) was successfully done. Present research work mostly concentrated on the scale up and scale down of MFC for the commercial exploitation of the process.
Research work on microalgal biotechnology has been focused on the algal biorefinery concept. High rate algal biomass production was observed in controlled photobioreactors with subsequent use of the biomass as a source of food, feed, biofuels and bioactive compounds. Different types of custom-make photobioreactors, viz. airlift, bubble column, flat panel rocking, and helical photobioreactors were used. 8 flat plate rocking photobioreactors with DO, temperature, pH etc. online monitoring system were designed in collaboration with Oslo University, Norway. CO2 sequestration was successfully carried out. 20 L airlift bioreactor was used for the algal biomass production in autotrophic as well as mixotrophic conditions. The spent medium of the biohydrogen production process was successfully utilized to increase the lipid accumulation in microalgae. Algal biomass from two stage cultivation was used for biodiesel production. Under mixotrophic growth, maximum lipid content obtained was 58±0.34 % w/w of DCW. An effort was made to extract the value added products like phycocyanin and related phycobilin proteins using Nostoc sp. The mixing pattern and flow characteristics in different photobioreactors are being studied using Computational Fluid Dynamics (CFD). Cheap and environment friendly methods of microalgal biomass harvesting are being studied. The Life Cycle Analysis (LCA) and socio-economic studies provide a final conclusion to our overall research. Presently, two projects have been undertaken in the DBT-Pan IIT. Two International Conference / Workshop were conducted so far: "Algal Biorefinery" (ICAB 2013) and "Use of solar energy for Co2 capture, algae technology and hydrogen production, and subsequent use of algae biomass for commercial purposes".
Alkaline lipase production using a newly isolated chemoheterotroph, Citrobacter freundii IIT-BT L139 is being studied. This Lipase is characteristically novel as a alkaline thermostable enzyme with significantly high specific activity. The bacterium is inhabitant of local soils, belongs to the family Enterobacteriaceae, coincidently this bacterium also produces molecular hydrogen through dark fermentation.
The studies were aimed to deal the problems involved in glucoamylase production using Aspergillus awamoriNRRL 3112. Effect of various physico-chemical parameters on the production and yield has been monitored. Flow characteristics (rheology) of the medium during fermentation had been taken into consideration. A putative neural network model was predicted for the batch growth pattern from the initial conditions, which eliminates the requirement of a large amount of data for modeling.
[Source, CPCB, 2000]. As an estimate 5 MW power can be generated by using landfill gas as fuel for five landfills and 70 tonnes of organic fertilizer will be produced daily as bye product. Further there will be no toxic liquid or gas effluents from the plant. So, in Indian scenario if landfill gas is tapped as a potential source of energy dual purpose of waste stabilization and gaseous energy recovery can be achieved.
The suitability of different agricultural residues in the biomethanation process was studied both singly and in combination. The potentialities of theses residues was found to be excellent. A mixture of water hyacinth, algae, cow dung and untreated rice husk (1:1:1:0:9) was better with respect to methane production, fuel value, NPK value of the digested residue and so on, in comparison to cow dung alone.
Pseudomonas putida MTCC 1194 was employed in biodegradation of phenol in industrial wastewater using a Ca-alginate immobilized system. Effect of different process variables like, initial phenol concentration, temperature, cell loading, bead size, etc. has been studied. The kinetic parameters for immobilized system have been determined from Lineweaver-Burk and Eadie-Hofstee plots.
The biological process for clean energy gaseous energy generation encompasses biohydrogen and biomethane production. The carbon footprint of biohydrogen and biomethane production processes is less as compared to chemical processes. Biohydrogen can be produced from organic wastes at ambient temperature and atmospheric pressure, thereby generating a sustainable process that subsequently helps in waste stabilization. The major routes for biological hydrogen production are direct and indirect biopholysis photolysis of water by blue-green algae and microalgae, oxidation of organic acids by photofermentation, and dark fermentation (using mesophilic or thermophilic bacteria). Nevertheless, each of the above-mentioned processes is associated with its respective advantages and limitations. Biophotolysis of water and photofermentation yield a very low rate of hydrogen production, and internal lighting requires additional energy input. Scaling-up of these processes is also difficult. Dark fermentation, on the other hand, is independent of light energy, requires moderate process conditions, and is less energy consuming. In addition, biogas generation process is mainly governed by two groups of microflora: acidogens and methanogens. Little information is available to find out the suitability of acidogens on hydrogen production, which may be considered potential microflora in the dark fermentation process. Thus, the dark fermentation process is considered a most promising method for biohydrogen production amongst all other processes. The spent media of the dark fermentation process contains a significant amount of volatile fatty acids such as acetate, butyrate, propionate, etc. These volatile fatty acids are suitable substrates for methanogens. Therefore, integration of the biohydrogen with biomethane processes under the eponym of “biohythane” could help in the improvement of gaseous energy recovery. The integration of the biohydrogen and biomethanation processes is challenging, and an immediate emphasis is required to develop human resource, expertise, and infrastructure to it. Intensive research work have been carried out to justify the suitability of the biohythane process as a most promising technology for the efficient utilization of the organic waste for the gaseous energy recovery.