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

laundry, dish washing, etc.; with “medium acceptance” = 5 for toilet flushing and irrigation
(the persons do not get in direct contact with purified water); and “low acceptance” = 1, if only
one application like toilet flushing or irrigation is accepted. In total, the weighting of this sub
issue is 5 % within the utility analysis.
The ecological awareness (S2) of a company or of persons can lead to an
implementation of a greywater treatment plant, although the amortisation of the project is not
demonstrative. The project of company DEHOUST in Ankara/Turkey (cf. 3.2.) is such an
example (Sellner, Grauwasserrecycling - DEHOUST GmbH, 2011). Hence, such motives are
weighted with 5 % within the assessment. If the “ecological awareness” is high, the rating is
10; for “medium awareness” it is 5; and for “low awareness” it is 1.
Finally, sub issue S3 (pioneer in this area) is a stimulus for the implementation of
greywater treatment via membrane bioreactor. It goes in the same direction as S2. However,
according to marketing aspects, there is an incentive to become a pioneer in this technology;
therefore it was accounted with 4 % in the total weighting. The rating of 10 can be chosen if
the “project is a pioneer in the area”, but if there are other MBR projects applied in the region
as well, a rating of 1 can be given.
Basically, the classification 0, 1, 5, and 10 was selected for the estimation within the
rating, in order to make it easier to choose a value. Certainly it is possible to give ratings
between 0 and 10, but it is difficult to define differences e.g. between 2 and 3. An additional
advantage is that the different ratings get more influence, which makes the result of utility
analysis more obvious.
If there is no data available, the criterion is assessed with N/A (“not available”) in a
separate column. In the Excel-sheet, there are N/A answers counted in order to be aware of
the inaccuracy of the utility analysis, in case there are too many N/A-answers. A good
valuation of a certain project can only be achieved by a good data basis. An appraisal, which
includes more than 5 N/A answers must be considered as not meaningful. Within the
assessment matrix, the N/A-answers are counted with 0. In total, a weighting of 100 %,
minus the weighting of sub issues that have been answered with N/A, can be achieved. An
adaption of 100 % is not calculated in case there are N/A values, as this might change the
influence of sub issues (change of calculation basis).
2.4.4 UTILITY ANALYSIS
For the utility analysis of international transferability of greywater treatment via MBR, a
few issues are mandatory. Only with fulfilment of the following aspects, an assessment of
technology transfer makes sense. Table 9 provides a list of general requirements for
greywater treatment application via MBR technology.
Table 9: General requirements for greywater treatment application via membrane bioreactor;
(by K. Löw)
M Mandatory criteria to install a greywater
treatment plant with MBR technology
M1 General acceptance of greywater reuse
M2 High requirements concerning quality of
recycled water
M3 Stable availability of energy
M4 Temp. > 12 °C
M5 Trained staff for operation available
First of all, the general acceptance of greywater recycling (M1) is mandatory. In some
circumstances, reuse of purified greywater is not accepted due to religious reasons.
Especially in muslim-dominated areas, there is often uncertainty, if recycled water meets the
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