8.6 Environmental Implications
179
The amount of water used in the washing of the biomass was not specified in
the said study (Tabarsa et al. 2018). Assuming a 1:10 ratio of dry biomass to tap
water, such that 10 mL of water is required per gram for washing stage. For the
main extraction, 20 mL of water is used per gram of Ulva. To therefore obtain the
crude ulvan extract, a minimum estimated 30 mL of water (10 mL tap water and
20 mL distilled water) is used. Compared to more water-consuming process such
as alginate extraction (see chapter on alginate), ulvan extraction consumed a fair
amount of water.
8.6.3 Alcohol
In the pretreatment stage, each gram of pulverized ulvan powder required 10 mL
of ethanol at 80% v/v concentration. This is used to dissolve off lipids, alcoholsoluble low molecular weight compounds and pigments. More ethanol is then used
for precipitation at a concentration of 70% with estimated volume of 20 mL per gram
of ulvan. Additional 99% ethanol (unspecified amount) is used for dehydration. Such
that for each gram of ulvan produced in the reported study, at least 30 mL of ethanol at
70–80% concentration is required for pretreatment and precipitation with more used
in dehydration post-extraction. As a greener alternative, bioethanol from renewable
source can be used. However, the sustainability of such extraction process will need
further consideration. The alcohol can also be cleaned and recovered through solvent
recovery processes such as adsorption, distillation and condensation.
8.6.4 Acetone
Following pretreatment with ethanol to remove lipids, pigments and low molecular compounds, the ulvan is washed with acetone (amount unspecified). Additional
acetone is used after the aqueous extraction in the final washing and dehydration
prior to drying of the crude extract. Acetone is an organic solvent sourced from
non-renewable sources. In the production of biopolymers such as ulvan, the goal is
to source polymers from renewable sources, and it is therefore important to seek
alternative solvents in the process of extraction.
8.6.5 Energy Consumption
In the extraction of the crude ulvan, energy consumed goes into heating of the system
to temperatures between 80 and 90 °C (Tabarsa et al. 2018). Heating 1 kg of water
by 1 K consumes 4.18 × 10
−3 J of energy (Bird et al. 2005). Further energy is
consumed in the drying process. Further energy consumption takes place in the other
179
The amount of water used in the washing of the biomass was not specified in
the said study (Tabarsa et al. 2018). Assuming a 1:10 ratio of dry biomass to tap
water, such that 10 mL of water is required per gram for washing stage. For the
main extraction, 20 mL of water is used per gram of Ulva. To therefore obtain the
crude ulvan extract, a minimum estimated 30 mL of water (10 mL tap water and
20 mL distilled water) is used. Compared to more water-consuming process such
as alginate extraction (see chapter on alginate), ulvan extraction consumed a fair
amount of water.
8.6.3 Alcohol
In the pretreatment stage, each gram of pulverized ulvan powder required 10 mL
of ethanol at 80% v/v concentration. This is used to dissolve off lipids, alcoholsoluble low molecular weight compounds and pigments. More ethanol is then used
for precipitation at a concentration of 70% with estimated volume of 20 mL per gram
of ulvan. Additional 99% ethanol (unspecified amount) is used for dehydration. Such
that for each gram of ulvan produced in the reported study, at least 30 mL of ethanol at
70–80% concentration is required for pretreatment and precipitation with more used
in dehydration post-extraction. As a greener alternative, bioethanol from renewable
source can be used. However, the sustainability of such extraction process will need
further consideration. The alcohol can also be cleaned and recovered through solvent
recovery processes such as adsorption, distillation and condensation.
8.6.4 Acetone
Following pretreatment with ethanol to remove lipids, pigments and low molecular compounds, the ulvan is washed with acetone (amount unspecified). Additional
acetone is used after the aqueous extraction in the final washing and dehydration
prior to drying of the crude extract. Acetone is an organic solvent sourced from
non-renewable sources. In the production of biopolymers such as ulvan, the goal is
to source polymers from renewable sources, and it is therefore important to seek
alternative solvents in the process of extraction.
8.6.5 Energy Consumption
In the extraction of the crude ulvan, energy consumed goes into heating of the system
to temperatures between 80 and 90 °C (Tabarsa et al. 2018). Heating 1 kg of water
by 1 K consumes 4.18 × 10
−3 J of energy (Bird et al. 2005). Further energy is
consumed in the drying process. Further energy consumption takes place in the other