An innovative greywater treatment system for urban areas ... - SuSanA

For the MAUT and AHP methods there are high demands on the preference articulation of
the decision maker necessary, such as result “A” is better than “B”. The utility analysis in
contrast requires only a medium rating on regulation of priority, equal scoring results without
preference are possible. In classical decision theory there are always two alternatives
comparable. The decision maker can always make a statement and a clear preference,
which of the two alternatives is strictly preferred (strict preference), or if both are equivalent
(indifference). Outranking procedures aim to give a decision aid in situations of uncertainty
and vagueness (Schuh, 2001).
One of the main tasks of this master’s thesis is to find a universally valid instrument for
decision-making. Therefore, an assessment system is meant to find the preferential cases of
MBR technology application and transfer. It shall identify whether it makes sense to
implement an MBR system at a particular place and in a particular application, or not. After
an in-depths literature review, the decision was taken to use the utility analysis. The main
reason for this decision has been the moderate demand of the tool for preference
articulation. In regard of the international transferability of membrane bioreactor treatment
technology, there are no first choice decisions available. Worldwide, many hotspots can be
identified for meaningful implementation of greywater recycling by MBR treatment. Due to a
wide range of influencing factors within the decision-making process, utility analysis seems to
be the most appropriate method, as it considers many aspects, not only economic ones such
as cost-benefit analysis. Another advantage is the easy and heuristic application of the
approach. An overview of further advantages, including completeness, transparency,
influence of new alternatives, clearness, required data input, etc., is listed in Table 6.
Table 6: Appraisal of utility analysis; (Schuh, 2001)
Attribute of utility analysis Performance
Completeness Yes
Transparency, traceability, objectivity Transparency and accountability is obtained
through the explicit disclosure of respective
preferences in the form of criteria weights and
aggregation procedures. This prevents that
subconsciously factors are incorporated in the
criteria rating.
Objectivity will not be ensured by the procedure
but at least traceability.
Accuracy and validity Yes
Reliability Yes
Influence of new alternatives No influence of new alternatives on existing
assessments
Structural openness of method Yes, new criterion requires merely new
weighting of all issues
Convenience and efficiency Yes
Clearness Yes
Required data input According to the analysis method, quasicardinal
data are necessary, but ordinal data
are often regarded as sufficient if a fundamental
transformability in benefit points is possible.
The realisation of utility analysis was done as follows: In the first step, the applicable
criteria for the decision making must be found. In respect of the international transferability of
a MBR treatment plant, e. g. economic considerations and their associated sub items (e. g.
acquisition cost, operating costs, etc.) are important. The sub criteria were weighted
according to their importance for the objective of the decision making process. Here,
percentages are given; the summary of all sub issues is 100% in total. This step results in a
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