Table 5 presents the indicators of the evaluation criteria and their quantitative and qualitative descriptions. These indicators were provided to the experts to weigh the evaluation criteria and alternatives.
Evaluation matrix of the upgrading alternatives of the old WWTP
| Dimensions . | Evaluation criteria . | Indicators . | ||
|---|---|---|---|---|
| A . | B . | C . | ||
| Economic | Capital cost (KRW) | 2,290,056 million | 1,084,791 million | 2,700,810 million |
| O&M cost (Increase rate) | Low | Medium | High | |
| Environmental | Improvement of bioreactors | Four-stage BNR | MLE + four-stage BNR | MLE + four-stage BNR |
| First flush treatment during the storm event (m3/d) | 3,260,000 | 1,360,000 | 2,000,000 | |
| Advanced treatment processes | Absence | Absence | Fine filtration and ozone/activated carbon | |
| Odor impact (Increase rate) | Low | Medium | Low | |
| Recycling possibility | Sludge pellet (339 t/d) Gray water | Sludge pellet(220 t/d) Gray water | Higher quality of treated water | |
| Sludge disposal | Drying 100% | Drying 42% + incineration 58% | Incineration 100% | |
| Energy independence (%) | 84 | 76 | 79 | |
| Social | Effective land use | Medium | Low | Medium |
| Public acceptance | Low | Medium | High | |
| Willingness to pay tariff | High | Medium | Low | |
| Dimensions . | Evaluation criteria . | Indicators . | ||
|---|---|---|---|---|
| A . | B . | C . | ||
| Economic | Capital cost (KRW) | 2,290,056 million | 1,084,791 million | 2,700,810 million |
| O&M cost (Increase rate) | Low | Medium | High | |
| Environmental | Improvement of bioreactors | Four-stage BNR | MLE + four-stage BNR | MLE + four-stage BNR |
| First flush treatment during the storm event (m3/d) | 3,260,000 | 1,360,000 | 2,000,000 | |
| Advanced treatment processes | Absence | Absence | Fine filtration and ozone/activated carbon | |
| Odor impact (Increase rate) | Low | Medium | Low | |
| Recycling possibility | Sludge pellet (339 t/d) Gray water | Sludge pellet(220 t/d) Gray water | Higher quality of treated water | |
| Sludge disposal | Drying 100% | Drying 42% + incineration 58% | Incineration 100% | |
| Energy independence (%) | 84 | 76 | 79 | |
| Social | Effective land use | Medium | Low | Medium |
| Public acceptance | Low | Medium | High | |
| Willingness to pay tariff | High | Medium | Low | |
Note: High, medium, and low pertain to relative comparison among the alternatives.