HYDROGEN PRODUCTION FROM WASTE BY ANAEROBIC FERMENTATION

Authors: YANG, PEILIN - UNIV. OF CALIF DAVIS; RUIHONG, ZHANG - UNIV. OF CALIF DAVIS; McGarvey, Jeffery - Jeff; BENEMANN, JOHN - BENEMANN ASSOC WALNUT CK

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 7/17/2005
Publication Date: 7/17/2005
Citation: Yang, P., Ruihong, Z., McGarvey, J.A., Benemann, J. 2005. Hydrogen production from waste by anaerobic fermentation. American Society of Agricultural Engineers, July 17-20, 2005, Tampa, FL. Paper No. 056019

Interpretive Summary: Cheese whey permeate, a waste product from cheese manufacturing, was used to make hydrogen gas in laboratory experiments. We were able to obtain large quantities of high quality hydrogen gas from this method.

Technical Abstract: Batch and continuous anaerobic fermentation experiments were performed to study the hydrogen production from cheese whey permeate under mesophilic conditions (35-38 oC). The batch experiments resulted in H2 yields of 8 and 10 mM/g COD fed at food to microorganisms ratios (F/M) of 1.0 and 1.5, respectively. The H2 content of the biogas was over 40%, with the remainder CO2. Over 95% of the lactose in the cheese whey permeate was fermented under best test conditions. In the batch fermentations on average twice as much butyric acid as acetic acid was produced, with no lactic acid detected. In the continuous fermentations the pH of the reactor was controlled in the range of 4.0-5.0 with sodium bicarbonate addition to the reactor feed. In these experiments loading rates of 5 to 14 g COD/L/day and hydraulic retention times (HRTs) of 12 to 24 h were tested. At pH below 4.0 or HRT shorter than 24 h, both biogas production rates and H2 content in the biogas decreased rapidly. The continuous fermentation process exhibited instabilities, with variable amounts of CH4 and H2 produced, attributed to the build-up of biofilms and retention of solids in the bioreactors. Under some operating conditions, continuous production of H2 for 2 to 3 week periods was observed, with maximum H2 yields of 2.0 to 2.3 mM/g COD fed. If this process can be controlled it may be possible to produce biogas with a desirable ratios of CH4 and H2, as such mixtures are known to reduce NOx emissions during biogas combustion in electricity production or other applications.