A new approach: single step bioprocessing

Low Risk Biorefinery: more product streams

Bioethanol production often faces survival challenging due to its lower margin profit at low oil price and downturn economic recession, which always puts a sole-ethanol production business in a high risky situation. Although there is an incentive from government support with policy, funding, and tax credit, whether it is sustainable profitable will determine the future of this industry. The relatively safe way is to have multiple bio-product streams that are composed of high value-added biochemicals such as lactic acid, succinic acid, glucaric acid to reduce the risks.

US-DOE top 12 building blocks give us the direction.

Partial recycling of pre- treated biomass will increase C6 sugar recovery yield

Paper mill sludge: a cheap sugar for biofuel/biochemicals

Modern paper companies produce large quantities of sludge when using recycled fiber. These sludges are the residue leftover from the paper recycling process and consist of unusable short cellulose fibers inks and dyes, clay, glues and other residue along with any chemicals used in the recovery process. The main disposal routes for paper sludge are land-spreading as agricultural fertilizer or incineration in CHP plants at the paper mill. However, the shortage of landfill space and more restrictive environmental regulations have made disposal more costly and less desirable.

A recent analysis of the sludges from a carton paperboard mill and a tissue paper mill indicating the cellulose are composed of 50-65% of total dry weight of sludge, which can be an important fiber source for biofuel and biochemical feedstock. These fibers with low amount of lignin make them more digestible for enzyme and the process is much simpler compared with the one from biomass. Prior to hydrolysis, there is a need for pre-cleaning or separation of the contaminants through mechanical/chemical process.

The chemical kinetics of the sulfuric acid hydrolysis

The chemical kinetics of the sulfuric acid hydrolysis of softwood was determined by J.F.Seaman in 1945 as follows:

• a 100% increase in acid concentration causes an increase of 153% in the k1 cellulose-hydrolysis-rate kinetics constant, but that increase only caused the k2-sugar product-degradation kinetics constant to increase 103%.
• a 10 degree rise in C temperature causes an increase of approximately 190% in the k1- cellulose-hydrolysis-rate kinetics constant, but then k2-sugar-product-degredation kinetics constant increased only 130%.