(655e) Immobilized Biological Hydrogen Fermentation with Chloroform Treated Granule

Biological hydrogen production has attracted more and more attention in recent years because of its ability to produce hydrogen energy while also addressing concerns on environment and fossil fuel replacement. In addition, the process is particularly environmental friendly because negatively valued materials (such as agricultural waste) can be used in the process. The low retention rate of hydrogen producing bacteria limits the productivity of a suspended-growth reactor due to the requirement for long hydraulic resident time (HRT) to maintain adequate bacteria population. Traditional immobilizaton methods such as calcium alginate entrapment have many limitations for appliacitons in hydrogen fermentation, such as the cost, the short duration time, the limited number of times for repeated-use etc. Chloroform treatment of granule was discovered from our previous study to be able to effectively eliminate the methane production and convert the culture into hydrogen production. Chloroform treated anaerobic granular sludge was proposed as immobilized hydrogen producing bacteria to be used in the immobilized hydrogen culture. This paper reports the studies on the performance of repeat batch cultures and continuous cultures inoculated with chloroform treated granule. The chloroform treated granule could be re-used for over 8 times without obvious structure damage. The upflow reactor packed with chloroform treated granules was studied and the hydrogen productivity reached 11.6 L/L/d at HRT of 5.3 hours. There were significant influence of initial pH and glucose concentration of the culture medium on the performance of the reactor. The optimum initial pH of the culture medium was neutral and the optimum glucose concentration of the culture medium was below 20 g COD/L. This study also investigated the possibility to integrate the immobilized hydrogen fermentation with chloroform treated granule and immobilized methane production with untreated granular sludge, and the experiment showed that the integrated batch cultures provided 1.01 mol hydrogen and 2 mol methane per mol glucose. The treatment of methanogenic granule and then using the treated granule as immobilized hydrogen producing sludge demonstragted advantages over other immobilization methods in that the granules provide hydrogen producing bacteria with a protective niche, a long duration and excellent settling velocity. The integrated two stage design for immobilized hydrogen fermentation and methane production offers a promising approach for modifying current anaerobic wastewater treatment processes to harvest hydrogen from the system.