Microbial World to Power Fuel Cells with Waste

According to the Nikkei Report, Sapporo Breweries Ltd. has developed bacterial degradation technology to turn food processing plant waste into hydrogen for fuel cells. Sapporo is testing its technology at a Hiroshima bread bakery, where unused dough is decomposed by microorganisms to generate hydrogen. "The system can generate 25,000 liters of hydrogen from 125 kg of dough, which otherwise would be thrown away. Combining this setup with a system for manufacturing would provide enough energy to meet the daily needs of five average households."

The article also reports the Kajima Corporation is developing a microbial fuel cell that generates electricity using a feedstock of sewage sludge.The Kajima fuel cell uses electrodes coated with microorganisms typically found in waste water and rice paddies. "These microbes release hydrogen as they metabolize the sludge, and this hydrogen reacts with oxygen to generate electricity." A prototype of the fuel cell can reportedly generate 130 watts of electricity per cubic meter."

(Cited from Industrial Biotech Innovation Report.)

A New Process for Continuous Production of Succinic Acid

A new efficient integrated membrane bioreactor-monopolar electrodialysis process was developed for succinate production at high yield (1.35 mol/mol), high titer (83 g/L) and high volumetric productivity (10.4 g/L.h) . The combination of these three parameters shows that this system could be economically viable for the development of a biological route to succinic acid production.

Oxidation of Glycerol

Glycerol can be oxidized to produce fine and specialty chemicals. Traditionally, oxidation can be conducted by mineral acids, enzymatic, or electron-chemical processes but selective catalytic oxidation turns to be productive, cheaper, and environmental friendly.

Oxidation products are useful as intermediates. e.g. glyceric acid is an intermediate for medicine manufacture; dihydroxyactone is a self-tanning agent in cosmostics; tartronic acid is an chelating agent; hydroxypyruvic acid is used for fruit maturation and intermediate for amino acids;Mesoxalic acid has potential application in organic syntheses.

Most of recent studies focus on heterogeneous catalysts such as supported platinum or palladium, and gold etc while some on homogeneous catalyst such as TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl).

The oxidation ususlly use air or oxygen as an oxidant at mild temperature (20-80 C) in the liquid pahse. The pH has an important impact on catalyst performance, product coversion rate and selectivity.

Purification of Crude Glycerol

The glycerol obtained from transesterification is separated from biodiesel by gravity. The concentration of this type of glycerol is ~50% (wt),which is so-called raw glycerol and contains the contaminants such as alcohol, soap, base catalyst, salts, and untreated organic materials.

Crude glycerol can be obtained through the following purification of raw glycerol:

1. Acidification of the soaps with HCl and separation of formed free acids by gravity
2. Neutralization with caustic soda
3. Evaporation for methanol recovery and water removal. The methanol recovered can be reused for biodiesel production. The the crude glycerol with 80-85% (wt.) can be obtained.

Crude glycerol purification:

1. Crude glycerol can be purified by vacuum distillation to a purity of 99.5% (wt).
2. Crude glycerol with diluted salt can be refined with ion-exchange
3. Crude glycerol with high salt content can be purified with ion exchange chromatography and thin film distillation.

Hydrogen from Biomass

Different process routes of hydrogen-production from biomass can be broadly classified as follows:

1. Thermochemical gasification coupled with water gas shift. Maximum conversion can be achieved. But significant gas conditioning is required and removal of tars is important.

2. Fast pyrolysis followed by reforming of carbohydrate fractions of bio-oil. It produces bio-oil which is the basis of several processes for development of fuels, chemicals and materials.But therr are chances of catalyst deactivation.

3. Direct solar gasification. Good hydrogen yield but requires effective collector plates

4. Miscellaneous novel gasification process.

5. Biomass-derived syn-gas conversion.

6. Supercritical conversion of biomass.Can process sewage sludge, which is difficult to gasify. Require a selection of supercritical medium

7. Microbial conversion of biomass.Waste water can also be treated simultaneously. Also
generates some useful secondary metabolites. Selection of suitable microorganisms is needed.