Environmental Engineering Reference
In-Depth Information
in Denmark. On a weight basis, sugar has the least impact in all categories, whereas vegetable
oil has the highest. It is important to point out that oils are 2.2 times calorie denser than
carbohydrates, so taking that into consideration, the production of vegetable oil is more in the
ballpark of sugar and wheat flour in terms of environmental impacts. Had the consumption
stage been included, oils are used in much less proportion for a meal preparation than
carbohydrates; so in terms of a meal as a functional unit, it is likely that oils have a lesser
impact than carbohydrates. Again, it all depends where the boundaries are set.
Case of enzymes
With exception of a few enzymes, for instance bromelain and papain—two commercial
proteases obtained from plants of the Bromeliaceae family and from the fruits of the
Carica
papaya
, respectively—most commercial enzymes are produced by microbial fermentation,
usually with genetically engineered microorganisms.
The industrial production of enzymes typically follows the following steps: fermentation
with microorganisms in a liquid medium, recovery of extracellular enzymes from the fermen-
tation broth, formulation that includes standardization and stabilization of the enzymes,
and biomass treatment that consists of the deactivation of the microorganisms and drying.
Figure 3.6 presents a flowchart for the production of enzymes at Novozymes in Denmark
(Nielsen et al., 2007). Every step has the inputs of heat, electricity, and water and produces the
direct output of wastewater and direct and indirect output of air pollution. In addition, every
step needs ingredients and materials that are used as nutrients for the fermentation (e.g., corn
starch, sucrose, glucose/maltose, corn steep powder, soybean meal, potato protein, phosphoric
acid, glucose syrup, ammonia), coadjutants for the recovery (e.g., diatomaceous earth, perlite,
sodium chloride), and formulation (e.g., sodium sulphate, cellulose powder, palm oil, wheat
starch, kaolin, calcium carbonate, titanium dioxide, sodium chloride, sucrose, calcium chlo-
ride, acetic acid) (Nielsen et al., 2007).
The number of ingredients to produce enzymes by fermentation is quite significant. The
production of every ingredient has imbedded impacts for their production. There are also a
number of mineral components, such as phosphoric acid, diatomaceous earth, perlite, sodium
chloride, kaolin, calcium and chloride, that are exploited from concentrated mineral deposits,
which is not sustainable in the long run.
Table 3.8 presents the most important environmental impacts for five enzymes produced
by Novozymes in Denmark. According to Nielsen et al. (2007), the highest impact for all
five enzymes happens at the fermentation and production of raw materials stages. A varia-
tion by a factor of 10 in some cases is observed on impacts between the enzyme at the
lowest end (Termamyl 120 L) and the one at the highest end (Novamyl 10,000 BG).
Carbohydrates,
protein, mineral salts
and vitamins
Formulation
agents
Filtration
materials
Fermentation
broth
Enzyme
liquor
Enzyme
product
Fermentation
Recovery
Formulation
Market
Micro-
organisms
Biomass
treatment
NovoGro
Agriculture
Figure 3.6
Flowchart for the production of enzymes by Novozymes in Denmark.
From Nielsen et al., 2007, reproduced with permission from Springer.
