Page 138 - Materials Chemistry, Second Edition

124 K. T. Lee and C. Ofori-Boateng

Fig. 15 Total environmental
impacts associated with the
production of PME

The oil milling stage contributed approximately 6 % of the total environmental
impacts (Fig. 15). Human health, ecosystem depletion, and resource use for the oil
milling stage recorded a percent environmental impact share of 13.01, 0.56, and
0.16 %, respectively.

5.4 Emissions Associated with CPO Refinery

The most dominant impact categories within the CPO refinery are carcinogens,
climate change, fossil fuel use, and respiratory organics with contribution of 31.48,
14.34, 4.92, and 2.34 % of the total impacts for the PME production system,
respectively (Fig. 13). The emissions from this stage come from the use of fossil
fuel emitting N 2 O, CO 2 , CO, particulate matter, respiratory gases, etc., which
result in these significant impact categories.
On a single score, the CPO refinery contributed approximately 0.002 % of the
total impacts associated with PME production (Fig. 14). Human health, ecosystem
depletion, and resource use were 0.84, 0.15, and 0.20 % of the total impacts,
respectively.

5.5 Emissions Associated with Transesterification Stage

The significant impact potentials within the transesterification stage are carcino-
gens, respiratory organics, climate change effect, ecotoxicity, and fossil fuel use
with contributions of 13.64, 30.31, 28.77, 37.19, and 43.59 %, respectively
(Fig. 13). These are due to the emissions resulting from the use of fossil fuel,
sodium hydroxide, phosphoric acid as well as wastewater containing soap stocks