96
T. Gichamo et al.
Table 11.2
Decision matrix of the natural wastewater treatment methods
Alternatives/criteria
Pollutants
removal
efficiency
Land
requirement
Capital
cost
Maintenance
cost
Health risk
Hydrogeological risk
Ecological
benefit
Subjected to
seasonal
effects
Aim (max/min)
Max
Min
Min
Min
Min
Min
Max
Min
Importance of weight VH
VH
VH
VH
VH
VH
VH
H
Stabilization pond
9
5
4
3
2
3
8
3
Constructed wetland
8
6
6
4
3
3
8
6
Use of aquatic plants 9
6
6
6
4
2
7
7
Soil filters
5
6
4
2
3
5
4
4
Reuse of wastewater
for irrigation
6
9
5
4
7
7
4
8