standards [14]. A socio-economic assessment was conducted following UNEP/
SETAC SLCA guidelines and CBA approach to complete the assessment [7–9].
2.1 Environmental LCA
The environmental performance of microalgal astaxanthin production was evaluated by conducting an attributional LCA with a cradle-to-gate approach. The study
included the environmental burdens associated with the production of the different
inputs to the system, the microalgae cultivation, harvesting and final carotenoid
extraction. This process competes with two alternative routes that consist in: (i) the
synthetic production from petrochemical feedstock and (ii) the fermentation process
by the yeast Phaffia rhodozyma [15]. Although synthetic astaxanthin dominates the
current market and has a more competitive price, it is not approved for human
consumption as a nutraceutical or pharmaceutical. Recent studies suggest that the
antioxidant activity of natural astaxanthin is significantly higher [11]. Thus, both
the microalgae- and the yeast-based routes are suitable for its production, although
microalgae process tends to have a higher yield.
The goal of the LCA was the identification of the main stages contributing to the
environmental impacts of a nutraceutical oleoresin containing 10% astaxanthin
while taking the influence of scale-up into account. Three real facilities were
analysed, including a lab-scale system (15 L tubular airlift PBR), a semi-pilot
system (80 L annular PBR) and a pilot system (1000 L sequential airlift PBRs). The
production system was divided into 5 stages depicted in Fig. 1: (i) cleaning and
sterilisation, (ii) preparation of the inoculum and culture medium, (iii) cultivation,
(iv) harvesting and (v) extraction. The functional unit (FU) was defined as 1 kg
astaxanthin, considered as a realistic production level for the pilot-scale process.
Although this FU was not a realistic value for the lab process (which produces
approximately 1 g per batch), the results are referred to the same unit as the pilot
systems to facilitate the comparison of the environmental profiles.
The Life Cycle Inventory (LCI) data for the foreground system consisted of
average data obtained by on-site measurements. Water emissions were calculated
assuming that the remaining nutrients in the culture medium after algae growth
were directly discharged to water. Data for the background inventory were taken
from Ecoinvent v2.2 [16]. A system expansion approach was considered to include
the potential use of residual algal biomass as fertiliser. The biomass content of
nitrogen and phosphorous were calculated according to [11].
The Life Cycle Impact Assessment included the classification and characterisation stages, which were conducted according to CML 2 baseline 2001 V2.05
impact categories [17]. Environmental indicators of ten impact categories were
evaluated: abiotic depletion potential (ADP), acidification potential (AP),
eutrophication potential (EP), global warming potential over a 100-year timeframe
(GWP), ozone layer depletion potential (ODP), photochemical oxidants formation
potential (POFP) and toxicity related impact categories: human toxicity (HTP),
Sustainability Assessment of Blue …
477
SETAC SLCA guidelines and CBA approach to complete the assessment [7–9].
2.1 Environmental LCA
The environmental performance of microalgal astaxanthin production was evaluated by conducting an attributional LCA with a cradle-to-gate approach. The study
included the environmental burdens associated with the production of the different
inputs to the system, the microalgae cultivation, harvesting and final carotenoid
extraction. This process competes with two alternative routes that consist in: (i) the
synthetic production from petrochemical feedstock and (ii) the fermentation process
by the yeast Phaffia rhodozyma [15]. Although synthetic astaxanthin dominates the
current market and has a more competitive price, it is not approved for human
consumption as a nutraceutical or pharmaceutical. Recent studies suggest that the
antioxidant activity of natural astaxanthin is significantly higher [11]. Thus, both
the microalgae- and the yeast-based routes are suitable for its production, although
microalgae process tends to have a higher yield.
The goal of the LCA was the identification of the main stages contributing to the
environmental impacts of a nutraceutical oleoresin containing 10% astaxanthin
while taking the influence of scale-up into account. Three real facilities were
analysed, including a lab-scale system (15 L tubular airlift PBR), a semi-pilot
system (80 L annular PBR) and a pilot system (1000 L sequential airlift PBRs). The
production system was divided into 5 stages depicted in Fig. 1: (i) cleaning and
sterilisation, (ii) preparation of the inoculum and culture medium, (iii) cultivation,
(iv) harvesting and (v) extraction. The functional unit (FU) was defined as 1 kg
astaxanthin, considered as a realistic production level for the pilot-scale process.
Although this FU was not a realistic value for the lab process (which produces
approximately 1 g per batch), the results are referred to the same unit as the pilot
systems to facilitate the comparison of the environmental profiles.
The Life Cycle Inventory (LCI) data for the foreground system consisted of
average data obtained by on-site measurements. Water emissions were calculated
assuming that the remaining nutrients in the culture medium after algae growth
were directly discharged to water. Data for the background inventory were taken
from Ecoinvent v2.2 [16]. A system expansion approach was considered to include
the potential use of residual algal biomass as fertiliser. The biomass content of
nitrogen and phosphorous were calculated according to [11].
The Life Cycle Impact Assessment included the classification and characterisation stages, which were conducted according to CML 2 baseline 2001 V2.05
impact categories [17]. Environmental indicators of ten impact categories were
evaluated: abiotic depletion potential (ADP), acidification potential (AP),
eutrophication potential (EP), global warming potential over a 100-year timeframe
(GWP), ozone layer depletion potential (ODP), photochemical oxidants formation
potential (POFP) and toxicity related impact categories: human toxicity (HTP),
Sustainability Assessment of Blue …
477