Biorefineries using waste – production of energy and chemicals from biomasses by micro-organisms - Biomass as Energy Source: Resources, Systems and Applications - page 239

Results show that the use of crop residues in a biorefinery saves GHG emissions and reduces
fossil energy demand. For instance, GHG emissions are reduced by about 50% and more than
80% of non-renewable energy is saved (Cherubini and Ulgiati, 2010).
For example, succinic acid co-production can enhance the profit of the overall biorefinery by
60% for a 20 years plant lifetime. Results of Vlysidis et al . (2011) indicate the importance of
glycerol when it is utilized as a key renewable building block for the production of commodity
chemicals. Luo et al . (2010) have estimated that the potential worldwide demand of succinic
acid and its derivatives can reach 30 million tonnes per year. Thus, succinic acid is a promising
high-value product if production cost and market price are substantially lowered. The results of
the economic analysis show that a refinery has great potentials compared to the single-output
ethanol plant.

13.7 BIOMASS AND RAW MATERIALS

Various potential biomass raw materials are listed in Table 13.1. It is noteworthy that almost
all fields of plant or animal materials exploiting industries are producing biomass wastes. Their
utilization for bioprocesses should be considered as a self-evident practice. For example, microbial
enzymes can be used in tanning and in other processes designed for the treatment of animal
hides (Kamini et al ., 2010). These enzymes include bacterial and fungal proteinases, specific
proteinases like keratinizes, and lipases.
Some conclusions concerning REMOWE project study batch fermentation tests in the Baltic
Sea region regarding the municipal wastes (Behrendt et al. , 2011):

• “already dumped waste or municipal waste older than six months is not worth the effort to be

prepared for anaerobic digestion

• if working with waste water sludge, the high water content has to be considered when thinking

about transporting the sludge, or whether an on-site anaerobic fermentation e.g. on the sewage
plant site would be more useful

• animal faeces as cow manure can be a suitable co-substrate, but the sole use does not produce

very high methane amounts

• biodegradable kitchen and canteen waste has always different compositions especially through-

out the seasons and plant design has to be adapted therefore, but methane outcomes deliver
promising results and it also does not compete with composting as the digestate from biowaste
fermentation can easily be used as fertilizer

• agricultural products or overproduction as hay silage and ley crops silage deliver methane

amounts and process behavior as expected, but the methane yields really depend on the age of
the material (anaerobic digestion is useful in most of the cases)

Table 13.1. Potential raw materials for bioconversion to chemicals, solvents and animal feed (Modified
from Singh and Mishra, 1995).

Sugar containing Starch containing Lignocellulosic Animal waste

- molasses - cereal grains - agricultural residues - slaughter house wastes

- whey - corn - forest residues - manure

- sweet sorghum - sorghum - wood sulfite waste - leather industry wastes

- sugarbeet - barley - other pulp and paper

- sugarcane - wheat bran industry waste

- fruit wastes - potato - waste paper

- beverage industry - corn and potato - municipal solid waste

wastes industry wastes - peat

- algae