دانلود رایگان مقاله لجن فاضلاب شهری پایداری و انتقال برای محیط زیست شهر

abstract

The treatment of urban sewage sludge is of vital importance for mitigating the risks of environmental contaminations, and the negative effects on human health. However, there are usually various different technologies for the treatment of urban sewage sludge; thus, it is difficult for decision-makers/stakeholders to select the most sustainable technology among multiple alternatives. This study aims at developing a generic multi-criteria decision support framework for sustainability assessment of the technologies for the treatment of urban sewage sludge. A generic criteria system including both hard and soft criteria in economic, environmental, social and technological aspects was developed for sustainability assessment. The improved analytic hierarchy process method, namely Best-Worst method, was employed to determine the weights of the criteria and the relative priorities of the technologies with respect to the soft criteria. Three MCDM methods including the sum weighted method, digraph model, and TOPSIS were used to determine sustainability sequence of the alternative technologies for the treatment of urban sewage sludge. Three technologies including landfilling, composting, and drying incineration have been studied using the proposed framework. The sustainability sequence of these three technologies determined by these three methods was obtained, and finally the priority sequence was determined as landing filling, drying incineration and composting in the descending order.

4. Discussion

It is apparent that the results determined by TOPSIS are consistent to that determined by SWM, in which landing filling is the most sustainable technology for the treatment of urban sewage sludge, followed by Dry Incineration and Composting. However, the results determined by SWM and TOPSIS are different from that determined by the diagraph model. The main reason is that the digraph model determines the sustainability indices of these technologies by calculating the permanency of the corresponding matrices in which no negative sign appears in the permanency function and no information is lost (Lanjewar et al., 2011). However, it is worth pointing out that it is difficult to inform decision-makers which method is correct or more accurate, because different stakeholders have different preferences and willingness; then, decision-makers can use all the determined results as a reference for decision-making. For instance, a final consensus can achieved by the rule of “the minority is subordinate to the majority” (Ren et al., 2015c), thus, the final sustainability sequence of these three technologies in the descending order is landing filling, dry incineration, and composting.