11 Ranking of Natural Wastewater Treatment Techniques …
95
11.4 Results
In this study, VIKOR, a multi-criteria decision-making technique method has been
applied for the analysis of the natural wastewater treatment methods performance.
For this aim firstly the decision matrix of the natural wastewater treatment methods
has been constructed and obtained (Table 11.2).
The importance weights of each parameter for fundamental scales of comparison
selected by the experts are given in Table 11.3 in the linguistic scale and triangular
fuzzy scale.
And the importance weights of the parameters defuzzified using the Yager index
to obtain a single value out of the triangular fuzzy numbers and normalized for the
use in the VIKOR technique. Then the best ( f
∗
i ) and the worst values ( f
−
i ) sets of
the alternatives based on each criterion have been calculated as shown in Table 11.4.
The utility (S j ) and the regret (R j ) measures of each alternative have been computed
for each natural wastewater treatment methods (see Table 11.5). The natural wastewater treatment methods were compared based on comparison criteria and weight
selected. The natural wastewater treatment methods addressed in this study have indicated different performance levels when evaluated with similar comparison criteria
(see Table 11.6). The criteria are selected predominantly based on the environmental,
economic, and health impacts of the wastewater treatment methods. The ranking of
the treatment methods was computed for the cumulative effects of all evaluation
criteria. The results indicated (see Table 11.6) that the stabilization pond is the first
ranked and the reuse of wastewater for irrigation is last ranked. Hence, it is logical
to conclude waste stabilization pond is the best natural wastewater treatment method
among the methods addressed in this study. The finding of this study is in agreement
with (Gichamo et al. 2020; Ouyang et al. 2015). Furthermore, the performance of
waste stabilization pond can diminish BOD 5 , suspended solid ammonia nitrogen,
and phosphorous up to 90%, 93% 91%, and 84% respectively, (Surampalli et al.
2007). The other study by waste stabilization pond ranked at first thus, achieved 94%
removal of total nitrogen, 93% of nitrate nitrogen, and 96% of ammonia nitrogen
(Duan and Fedler 2010).
In VIKOR modeling the alternative with minimum Q i value is the best alternative
and the one with maximum Q i is the worst alternative. The result (Table 11.6) indicated according to the order of best to worst alternatives measured by the balanced
effects of a given criterion. For all the given evaluation criteria, the waste stabilization pond was observed as an appropriate wastewater treatment method because the
method meets the objective of each evaluation criterion. The method is independent
of seasonal variability and related climatic variations, the overall cost of the method
is fair and it did not cause/cause a little negative health impact on humans working
on-site or living around as compared with other methods.
The utility (S j ) and the regret (R j ) measures of each alternative have been
calculated and presented (Table 11.5).
95
11.4 Results
In this study, VIKOR, a multi-criteria decision-making technique method has been
applied for the analysis of the natural wastewater treatment methods performance.
For this aim firstly the decision matrix of the natural wastewater treatment methods
has been constructed and obtained (Table 11.2).
The importance weights of each parameter for fundamental scales of comparison
selected by the experts are given in Table 11.3 in the linguistic scale and triangular
fuzzy scale.
And the importance weights of the parameters defuzzified using the Yager index
to obtain a single value out of the triangular fuzzy numbers and normalized for the
use in the VIKOR technique. Then the best ( f
∗
i ) and the worst values ( f
−
i ) sets of
the alternatives based on each criterion have been calculated as shown in Table 11.4.
The utility (S j ) and the regret (R j ) measures of each alternative have been computed
for each natural wastewater treatment methods (see Table 11.5). The natural wastewater treatment methods were compared based on comparison criteria and weight
selected. The natural wastewater treatment methods addressed in this study have indicated different performance levels when evaluated with similar comparison criteria
(see Table 11.6). The criteria are selected predominantly based on the environmental,
economic, and health impacts of the wastewater treatment methods. The ranking of
the treatment methods was computed for the cumulative effects of all evaluation
criteria. The results indicated (see Table 11.6) that the stabilization pond is the first
ranked and the reuse of wastewater for irrigation is last ranked. Hence, it is logical
to conclude waste stabilization pond is the best natural wastewater treatment method
among the methods addressed in this study. The finding of this study is in agreement
with (Gichamo et al. 2020; Ouyang et al. 2015). Furthermore, the performance of
waste stabilization pond can diminish BOD 5 , suspended solid ammonia nitrogen,
and phosphorous up to 90%, 93% 91%, and 84% respectively, (Surampalli et al.
2007). The other study by waste stabilization pond ranked at first thus, achieved 94%
removal of total nitrogen, 93% of nitrate nitrogen, and 96% of ammonia nitrogen
(Duan and Fedler 2010).
In VIKOR modeling the alternative with minimum Q i value is the best alternative
and the one with maximum Q i is the worst alternative. The result (Table 11.6) indicated according to the order of best to worst alternatives measured by the balanced
effects of a given criterion. For all the given evaluation criteria, the waste stabilization pond was observed as an appropriate wastewater treatment method because the
method meets the objective of each evaluation criterion. The method is independent
of seasonal variability and related climatic variations, the overall cost of the method
is fair and it did not cause/cause a little negative health impact on humans working
on-site or living around as compared with other methods.
The utility (S j ) and the regret (R j ) measures of each alternative have been
calculated and presented (Table 11.5).