46
3 Chitin
(2) Mahtani Chitosan uses shrimp shell, while Company X uses crab shells as feed
material. (3) Mahtani Chitosan uses its protein sludge by-product as fertilizer, while
Company X uses theirs as animal feed.
However, it should be considered that the information presented here is based on
data from the company’s operation and therefore may vary for other companies as
such is by no means exhaustive. The goal here is to give an overview of the resource
requirements and environmental impact of the chitin production process.
3.6.1 Resource Utilization
The amount of raw material required depends on the type of feedstock being used
and the efficiency of the process. Crab and shrimp are most commonly used for
commercial chitin production due to their high chitin content. Table 3.1 shows chitin
yield/content for different sources of chitin based on reports from the literature.
Company X reports using 10 kg dry crab shell per kg of chitin produced, while
Mahtani Chitosan reportedly uses 33 kg of shrimp shells per kg of chitin produced.
Use of the waste aquatic materials for chitin and chitosan production diverts the
use of these materials as animal feed and as organic fertilizers, the main alternative
uses of these materials. The direct environmental impact therefore lies in the pressure;
this diversion puts on other resources used for animal feed and fertilizers.
3.6.2 Water Consumption
A lot of water is used in the process of washing the shells, washing after demineralization and deproteinization to get rid of the acids and alkali used to return the
solids to neutral. The chemical process generates more wastewater for this reason.
The water is either treated and recycled in-house or sent to external water treatment.
An alternative to the use of shell waste in the production of chitosan is to use
the shell waste as animal feed. Comparing the quantity of water used in chitosan
production to that use in preparation for crab shells as animal feed, less water is
actually consumed in the production of chitosan compared to using the crab shells
for animal feed. Further consideration must be made to the fact that the diversion of
the shell waste from animal feed to chitin production means increased demand for
other sources of animal feed such as soybeans and barley.
Mahtani Chitosan reportedly uses 167 L of freshwater per kg of chitin it produces
from shrimp shell. A further 250 L of water is then used for each kg of chitosan
produced per 1.4 kg of chitin. Company X in Europe reportedly uses 300 L of water
per Kg of chitin produced from crab shells. The data for water consumed during
chitosan production from chitin by Company X was not provided for confidentiality
reasons. At Mahtani Chitosan, the wastewater from the production process is treated
3 Chitin
(2) Mahtani Chitosan uses shrimp shell, while Company X uses crab shells as feed
material. (3) Mahtani Chitosan uses its protein sludge by-product as fertilizer, while
Company X uses theirs as animal feed.
However, it should be considered that the information presented here is based on
data from the company’s operation and therefore may vary for other companies as
such is by no means exhaustive. The goal here is to give an overview of the resource
requirements and environmental impact of the chitin production process.
3.6.1 Resource Utilization
The amount of raw material required depends on the type of feedstock being used
and the efficiency of the process. Crab and shrimp are most commonly used for
commercial chitin production due to their high chitin content. Table 3.1 shows chitin
yield/content for different sources of chitin based on reports from the literature.
Company X reports using 10 kg dry crab shell per kg of chitin produced, while
Mahtani Chitosan reportedly uses 33 kg of shrimp shells per kg of chitin produced.
Use of the waste aquatic materials for chitin and chitosan production diverts the
use of these materials as animal feed and as organic fertilizers, the main alternative
uses of these materials. The direct environmental impact therefore lies in the pressure;
this diversion puts on other resources used for animal feed and fertilizers.
3.6.2 Water Consumption
A lot of water is used in the process of washing the shells, washing after demineralization and deproteinization to get rid of the acids and alkali used to return the
solids to neutral. The chemical process generates more wastewater for this reason.
The water is either treated and recycled in-house or sent to external water treatment.
An alternative to the use of shell waste in the production of chitosan is to use
the shell waste as animal feed. Comparing the quantity of water used in chitosan
production to that use in preparation for crab shells as animal feed, less water is
actually consumed in the production of chitosan compared to using the crab shells
for animal feed. Further consideration must be made to the fact that the diversion of
the shell waste from animal feed to chitin production means increased demand for
other sources of animal feed such as soybeans and barley.
Mahtani Chitosan reportedly uses 167 L of freshwater per kg of chitin it produces
from shrimp shell. A further 250 L of water is then used for each kg of chitosan
produced per 1.4 kg of chitin. Company X in Europe reportedly uses 300 L of water
per Kg of chitin produced from crab shells. The data for water consumed during
chitosan production from chitin by Company X was not provided for confidentiality
reasons. At Mahtani Chitosan, the wastewater from the production process is treated