عنوان مقاله [English]
Today, the use of environmentally friendly alternative technologies in various applications is a necessity. These technologies are less likely to lead to environmental pollution than conventional technologies. One of the environmentally friendly technologies as a subset of biotechnologies is phytoremediation. One of the branches of phytoremediation that has been considered by researchers in the last two decades is salt phytoremediation or in other words, phytodesalination. Phytodesalination has been used first as a technology to reduce soil salinity and then as a method to reduce salinity of saline water and wastewater.
Although phytodesalination of saline water as an emerging and environmentally friendly technology has raised hopes for desalination with a view to sustainable water supply but it undoubtedly has limitations that may overshadow its use as a practical method. It seems that conducting a SWOT analysis with the aim of identifying the strengths, weaknesses, opportunities and threats related to this method and formulating related strategies to chart a brighter future for this technology, can be useful. One of the shortcomings of SWOT analysis is its qualitative aspect, so that in this method only a number of factors in the groups of strengths, weaknesses, opportunities and threats are determined without mentioning the relative importance of these factors and groups. In order to address this shortcoming, some researchers have used Multi-Criteria Decision Making (MCDM) methods to determine the relative importance of SWOT factors and groups. In this paper, after identifying strengths, weaknesses, opportunities and threats of phytodesalination by constructed wetland () containing halophytic plants, using expert opinions through Fuzzy AHP method (Buckley analysis), local and general priorities of the factors of each of the four SWOT groups have been calculated and the factors with higher priorities and as a result the types of strategies that should be adopted have been identified.
The results show that in the group of strengths (S), factor S1, "environmental compatibility" had the highest priority (p = 0.47), after that, factors S4,“acceptable treatment efficiency” (p = 0.2), S3, “cost-effectiveness compared to other methods” (p = 0.18), S5, “the possibility of linking with bioenergy production methods” (p = 0.09) and S2, “by-products if useful plants are used” (p = 0.07) ) are ranked second to fifth, respectively. In the group of weaknesses (W), factor W1, "dependence on evapotranspiration" had the highest priority (p = 0.47), after that, factors W2, “complexity in plant-based systems and their management problems” (p = 0.19), W5, “ slow process and long time for growth” (p = 0.18), W4, “the problem of biomass disposal and the possibility of salt return due to it “(p = 0.11) and W3, “the inability of most halophytes to be used as useful crops” (p = 0.06) are ranked second to fifth, respectively.
In the group of opportunities (O), factor O3, "reduction of water resources and the need to the use of unconventional resources" had the highest priority (p = 0.29) that followed by factors O4, “the existence of huge saline water resources (seas and saline rivers)” (p = 0.28), O5, “the possibility of using genetic engineering to modify salinity tolerance characteristics” (p = 0.24), O1, “ high biodiversity of halophytes” (p = 0.12) and O2, “high energy and carbon footprint in other desalination methods” (p = 0.06) as second to fifth ranks, respectively. Finally, in the group of threats (T), factor T4, "lack of appropriate financial incentives and non-participation of related economic sectors in salinity research" had the highest priority (p = 0.43) that followed by factors T1, “lack of understanding of water crisis and need to the use of unconventional water resources” (p = 0.28), T5, “ the possibility of extinction of some suitable plant species” (p = 0.12), T2, “lack of research priority by biotechnology and phytoremediation researchers” (p = 0.12) and T3, “the lack of systematic methods for selecting suitable species” (p = 0.06) as second to fifth ranks, respectively.
After analyzing the factors of each group, the factor with the highest local priority in a group is selected as the representative of that group to compare the groups and the final results of the comparison of these representatives are considered as the weight of the group. Comparing the groups, it was found that the two groups of weaknesses and opportunities had the highest weight (p = 0.353), followed by the group of threats in the second place (p = 0.214) and the group of strengths in third place (p = 0.08). The final step is to calculate the global priorities of the factors. To do this, the weight of each group was multiplied by the local priority of the following factors. Due to global priorities the first important factor belongs to the group of weaknesses (W1). This factor is the main problem of the phytodesalination method in CWs, i.e. dependence on evapotranspiration. Evaporation from the CW media surface and transpiration from plants along with the upward capillary flow in the CW causes the upper CW surfaces to fill with salt over time. This saline layer will increase the salinity of the incoming water to CW. Therefore, the most important step in the success of this method is to control evapotranspiration and reduce its amount.
The second most common factor is T4 in the threat group. This is due to the lack of appropriate financial incentives and the lack of participation of related economic sectors in salinity research. Therefore, according to experts, after solving the problem of dependence on evapotranspiration, the completion of research in the shadow of financial incentives is one of the most important factors in the success of the salt phytoremediation method in CWs wetlands. The third rank is a positive factor, i.e. O3 factor from the group of opportunities. This factor, which is reduction of water resources and the need to the use of unconventional resources, is an important opportunity for this method. In fact, this method can play a role as one of the solutions to the water crisis. The fourth place also belongs to an opportunity. This factor is the O4 factor i.e. the existence of huge sources of salt water (salt seas and rivers). The factor that, as an endless input, ensures the success of this method in terms of input stability. The fifth rank also belongs to a threat. This threat, factor T4, is a lack of understanding of the water crisis and the need to turn to unconventional resources. This lack of understanding exists both among the people and among the managers of the water sector. Therefore, it needs to provide the necessary education in this regard to strengthen this understanding. The next five factors are opportunity, weakness, weakness, threat and opportunity types, respectively. In other words, of the first ten factors, three are weakness, three are threats, and four are opportunities. Therefore, it seems that the strategies chosen for this system should be WT and WO.