Cement Energy and Environment

and thermophilic temperatures are attractive avenues for biological H2 production. The dark fermentation at thermophilic temperatures (60°C) is more advantageous. Many industrial organic wastewaters are discharged at elevated temperatures that can be directly used. Moreover, higher temperature condition leads to pathogenic destruction, lower risk of contamination by methanogenic archaea, a higher rate of hydrolysis, and higher H2 yield. In addition, during fermentation excess heat is generated that requires cooling for mesophilic cultures. Thermophilic biohydrogen production was also explored as an avenue for biological H2 production. A newly isolated organism, Thermoanaerobactrum Thermosaccharolyticum ST1 yielded a maximum of 2.7 mol H2/ mol glucose. The lab also focusses biohydrogen production using mixed and co-culture apart from pure cultures to make the process more feasible. One of the current major activities is related to in~tallation and commissioning of 10 m3 bioreactor for commercial exploitation of biohydrogen production process from organic wastes. The effluent generated from dark fermentation contains metabolites, such as volatile fatty acid which can be used further for biomethanation and biobutanol production for maximum energy recovery. Integration of biohydrogen production with biomethanation (BIOHYMET) makes the process overall more economical and sustainable. BIOHYMET production by such integrated process permits an increase in conversion efficiency of biomass to gaseous energy. An integrated two– stage anaerobic microbial dark fermentation process was also developed to produce biohydrogen gas (H2) and butanol using obligate anaerobe Clostridium acetobutylicum MTCC 11274. The strain is known to produce hydrogen along with volatile fatty acids in acidogenesis phase and butanol in solventogenesis phase using accumulated volatile fatty acid. A substantial plant for biohydrogen production using an 800 L reactor. A prototype 20 L packed bed reactor has also been developed for continuous hydrogen production. Such type of packed bed reactor uses cheaper environment-friendly lignocellulosic biomass as a matrix for whole cell immobilization. Our endeavour with large-scale biohydrogen production has motivated us to commercialize biohydrogen production process for decentralized energy solution. Intensive research work on improvement of hydrogen production using different organic wastes/residues and scale up of the process up to 10 m3 is in progress for the commercial exploitation of the production process (Figure 1). Another area of research in the laboratory on microalgal biotechnology focusses on the algal biorefinery concept. The efforts are concentrated on high rate algal biomass generation in controlled photobioreactors with subsequent use of the obtained biomass as a source of food, feed , biofuels and bioactive compounds. In the continuous mode of operation with Chiarella sorokiniana, the maximum biomass productivity of 0.11 g L-1 h-1 was observed at an optimum dilution rate of 0.05 h-1 when 5 per cent air-C02 (v/v) gas mixture was used. Biological fixation of C02 was also studied using industrial flue gas. The flue gas emitted from the oil producing industry contains mostly C02 and H2S (15.6 per cent v/v and 120 mg L-1, respectively) along with nitrogen, methane, and other hydrocarbons. The highest reduction in the C02 content of inlet flue gas was 4.1 per cent (v/v). Cyanobacteria were also used for C02 sequestration study. Anabaena sp. PCC 7120 was grown in customized airlift photobioreactors. Higher light utilization efficiency and a higher rate of C02 biofixation were observed with maximum biomass concentration of 0.71 g L-1 using BG11 medium under aerated conditions. Another new approach for C02 research has been r-----.;;;;;;;;;;;=::----,..-====o:---:-~-;;;;;;;;;;;;iiiiiiiiiiiiiiiiiiiiiiiiiiiiii;;;;;;;;;;;::;;;;;;;;;o;;;;::;;;;;;;;;;iiiiiiiiii;;;o;;;;=cl carried out on the development of continuous hydrogen production process especially in customized bioreactors. liT- Kharagpur has successfully designed • l'll:u.l: 10 ~capacity of pilot p&antfadlityU'Ider-mnstnEtion for biioh)drogen and commissioned pilot pmwctionfromdilrelentorganicwanesinHT~ 52 I ' r