SELECTION OF OPTIMUM ACTIVE TREATMENT TECHNOLOGY FOR ACID MINE DRAINAGE (AMD) USING SPHERICAL FUZZY ANALYTIC HIERARCHY PROCESS (SFAHP)
The Philippines is one of the most mineralized countries in the world. However, despite its positive impact on the economy, the production of acid mine drainage (AMD) due to extensive mining has caused detrimental effects on the environment. AMD occurs when pyrite and other sulfide minerals are expo...
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| Summary: | The Philippines is one of the most mineralized countries in the world. However, despite its positive impact on the economy, the production of acid mine drainage (AMD) due to extensive mining has caused detrimental effects on the environment. AMD occurs when pyrite and other sulfide minerals are exposed to air, microbial activities, and water. It is estimated that 1 mole of pyrite can produce at most 16 moles of hydronium ions, making the surrounding environment highly acidic. To this date, several efforts and treatment technologies have been proposed to manage the negative impacts of AMD. However, little effort has been made over the years to develop a generalized framework for the selection of the optimum treatment technology. The technology selection process involves systematic evaluation based on multiple but often conflicting criteria. This study proposed the use of the Spherical Fuzzy Analytic Hierarchy Process (SFAHP) as a Multi-Criteria Decision Analysis (MCDA) tool to select the optimum active treatment technology for AMD. Three treatment technologies were considered: 1) combination of conventional lime neutralization and sulfidogenic bioreactor (CLN + SB); 2) high-density sludge (HDS) process; 3) combination of two-step neutralization ferrite formation and sulfidogenic bioreactor (TSNFF + SB). The alternatives were evaluated using three criteria – technical aspect, economic aspect, and environmental aspect – and eight sub-criteria – robustness, ease of operation, ease to upgrade, CAPEX, OPEX, effluent quality, sludge production, and resource recovery. The analysis showed that the decision-makers have the highest importance for the environmental aspect when selecting a treatment technology. Aggregation of individual judgments and individual priorities yielded the same ranking: TSNFF + SB > HDS > CLN + SB. One-at-a-time sensitivity analysis was also done. Results indicated that the level of importance of the TSFNN + SB is largely attributed to the high level of importance given to the environmental aspect. A comparative study was also done by comparing the result with the obtained ranking from classical AHP. Both methods gave the highest score for TSNFF + SB but different rankings when equal weights were given for the criteria. |
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