## 3 Results and Discussion
### Limitations and Suggestions for Future Research  
The CBA of water reclamation projects in industrial parks conducted in this study shows the importance of environmental benefits of water reclamation projects, which increase the economic feasibility of the projects when they are taken into account. However, it should be noted that the CBA is based on many assumptions, and the applicability of the results critically depends on the validity of the assumptions. For example, the water treatment technology used in a targeted industrial park could be different from the ones chosen in this study, namely, UF and RO for water reclamation for industrial water supply and sand filtration, followed by chlorination for irrigation of plants and green areas, resulting in different costs of construction, operation, and maintenance. Further, the flow rate of irrigation water for each industrial park is quite specific. The amount of water supply for irrigation is uncontrollable and depends on the vegetation area, rainfall, evapotranspiration, season, and other factors related to water use by vegetation. Rough estimates of irrigation water in industrial parks might be obtained based on their green areas using the value suggested for calculating irrigation water demand in public parks, which is 1.7 mm/d in Thailand [51]. Taking into consideration local meteorological conditions and grass evapotranspiration, the irrigation water demands should be calculated as shown in Text S1, Tables S10 and S11. The calculation was made for grass as a representative crop, which resulted in an irrigation water demand of 1.9 mm/d in Chonburi. With this irrigation water demand, the irrigated green areas based on the flow rate scenarios would be in the range of 9-177 ha (Table S12). Although we conducted economic feasibility studies for a wide range of irrigation water flow rates (240-4800 m\({}^{3}\)/d), it is possible that the irrigationwater flow rate for a specific industrial park would be out of this range, particularly at low flow rates, such as industrial parks I2-I4 (43-56 m\({}^{3}\)/d) in Chonburi (Table S9). In these cases, the results of this study would not be applicable. Furthermore, it was assumed in the CBA that irrigation water would not be large enough to infiltrate groundwater and that there would be no adverse environmental impacts on soil and groundwater. Indeed, these assumptions can be considered limitations of our study, as they may not be true; thus, the environmental impacts of irrigation by reclaimed water should be considered in future studies.  
Further, the environmental benefits of not releasing heavy metals into water bodies when wastewater treatment plant effluent is reclaimed were not considered in this study, as their shadow prices are not currently available. Research on the environmental costs of pollutants other than COD, SS, N, and P, such as heavy metals, chemicals, and emerging pollutants, is still needed. Further research is also required on the ecosystem service values resulting from water reclamation projects in industrial parks. The socioeconomic impacts of water reclamation projects in industrial parks on other stakeholders, such as communities and the public, were also not considered in this study. For example, water reclamation in industrial parks can reduce overall water demand, making more water available to other sectors, such as agriculture, especially during drought periods. Additionally, there are health benefits to not releasing pollutants into the environment, which may result in less human exposure to these pollutants. Future research could translate and incorporate all aspects of environmental impacts analyzed in detail in LCA into CBA. The costs and benefits associated with these impacts could demonstrate the full value of water reclamation projects, potentially making them more feasible and appealing.