Page 62 - Materials Chemistry, Second Edition

Life Cycle Assessment of Municipal Wastewater and Sewage Sludge Treatment 43

and implemented in a full-scale WWTP, their contribution to the global impact can
be considered negligible.

3.5.3 toWard Water reuSe: HiGH Quality effluentS
Membrane-based technologies are usually considered a recommendable option
for tertiary treatment due to the possible reuse of the effluent. Tangsubkul et al.
(2005) compared several treatment technologies for the potential agricultural reuse
of wastewater, including MBR and continuous microfiltration (CMF). In a specific
work on MBR for water reuse, tertiary treatments were found to provide high-quality
effluents without increasing the environmental impact associated with the WWTP
(Ortiz et al., 2007). Technologies specifically designed for high-quality effluents
(chlorination plus ultraviolet treatment, ozonation, or ozonation with hydrogen per-
oxide) were compared by Meneses et al. (2010) and Pasqualino et al. (2011), who
concluded that the options evaluated presented similar environmental profiles and
that the environmental impact of the plant was only slightly increased when com-
pared with traditional ones.

3.6 INTEGRATING LCA IN THE DESIGN AND
SIMULATION OF NEW FACILITIES
The use of simulation and modelization to compare technologies can be of remark-
able interest in the decision-making process. Foley et al. (2010a) compared six dif-
ferent technologies for nutrient removal. The normalized results of the potential
impacts showed that to justify stringent nutrient removal, it would be necessary to
weight the eutrophication impact category three times more than other categories,
such as global warming or toxicity. A very similar approach was followed by Wang
et al. (2012) for three discharge levels, each one more demanding than the previous
one, finding that more stringent requirements for water quality led to a higher envi-
ronmental burden.
LCA and modeling have also been combined to select the most appropriate treat-
ment scenario for a given situation (wastewater to be treated, location, etc.) by means
of the implementation of the LCA methodology within the knowledge basis of a
decision support system (Garrido-Baserba et al., 2012).
Along these lines, the PIONEER_STP project will assess the impact of innova-
tive units (nowadays at laboratory or pilot scale or in their early stages of indus-
trial implementation) on the global plant efficiency and sustainability, taking into
account nutrients, energy, emerging pollutants (EPs), GHGs, and cost/benefit bal-
ances (Figure 3.5). As organic matter (OM) and nutrients will be targeted separately,
two of them will be focused on energy recovery from valuable organic matter and
two on nutrient removal/recovery. The processes can be combined into different
plant layouts (using a superstructure-based optimization framework), which will be
further optimized by modeling and simulation based on technical, environmental,
energetic, and economic aspects.