[Decision-making Analysis of Excess Sludge Pretreatment for Struvite Recovery Based on AHP-PROMETHEE Ⅱ Method]

Phosphorus is a non-renewable resource. The recovery of phosphorus from excess sludge by the struvite precipitation process has been applied on a full-scale. However, different sludge pretreatment methods have been used to release carbon, nitrogen, and phosphate from excess sludge, which could affect the subsequent struvite precipitation process. In this study, the decision-level analytical structure of the 3-layer and 6-index was constructed to evaluate the effects of six excess sludge treatment processes on struvite recovery. According to the preference ranking organization method for the enrichment of evaluations Ⅱ (PROMETHEEⅡ) decision-making analysis, enzymatic hydrolysis or enzymatic hydrolysis-anaerobic fermentation was the better sludge treatment choice for struvite recovery under the "product quality" priority case, while thermal hydrolysis or thermal hydrolysis-anaerobic fermentation could be better under the "time and economy" priority case. This study provides a recommendation for the selection and design of excess sludge treatment for struvite recovery.