## 6 Enviro-Economic Investigation  
The investigation determines the amount of SO\({}_{2}\), CO\({}_{2}\), and NO released by the MSS throughout its lifespan. Furthermore, it includes data on the overall embodied energy utilized to generate the MSS. Additionally, it provides information about the overall CO\({}_{2}\) reduction and the proportionate credit of carbon generated. The aforementioned parameters may be computed using the following equations [31; 32]:  
The following empirical formula is used to estimate the total amount of CO\({}_{2}\) emissions during the lifetime of the MSS.  
\[\text{CO}_{2}\text{ emission}=1.58\times\text{Embodied energy} \tag{10}\]  
Likewise,  
\[\text{SO}_{2}\text{ emission}=0.012\times\text{Embodied energy} \tag{11}\]  
\[\text{NO emission}=0.005\times\text{Embodied energy} \tag{12}\]  
The net CO\({}_{2}\) reduction during the life of the MSS may be determined using the equation below:  
\[\text{Net CO}_{2}\text{ mitigation for lifetime }=\frac{\left[\left(\text{Embodied energy }\left(\text{out}\right)\times\text{y}\right)-\text{Embodied energy }\right]\times 1.58}{1000} \tag{13}\]  
where y = 10 (lifespan in years)  
The desalination system's carbon credit and overall system embodied energy are determined by:  
\[\text{Embodied energy }\left(\text{out}\right)=\frac{\text{Annual yield }\times\text{latent heat}}{3600} \tag{14}\]  
For a 0.25 m\({}^{2}\) area, the yearly production is 233.5 L, and a latent heat of vaporization of 2260 kJ/kg is considered [33].  
\[\text{Carbon credit earned}=\text{Net CO}_{2}\text{ mitigated for lifespan }\times 9.99 \tag{15}\]  
Table 5 compiles the embodied energy (EE), components of a variety of materials, and energy density (ED) employed in the MSS [34; 35]. The total EE is required to calculate CO\({}_{2}\) emissions, sulfur emissions, nitrogen emissions, and other environmental and economic characteristics. When compared to the other materials employed in the system, glass had the highest value of 11,127.8 kWh/m\({}^{3}\) ED and accounted for 13.62 kWh of embodied energy. With 4.167 kWh/kg ED and an 8 kg mass, a plywood sheet with a thickness of 1.8 cm produced 33.34 kWh, the highest EE. An ED of 10.83 kWh/kg and an EE of 86.64 kWh were measured on 8 kg of galvanized iron which was utilized to manufacture a solar still inside walls and a basin liner.  
The system gained 3.75 kWh of EE from the 0.2 kg of the PVC collecting channel, which had an 18.75 kWh/kg ED. A minimum EE of 0.83 kWh was produced by the additional parts such as the silicon glue and double-sided foam tape. Banana stems as a biowaste that were also employed in the MSS for the purpose of enhancing water productivity account for 0.85 kWh. Consequently, the overall EE for the entire MSS will be 139 kWh by summing the EE for each individual material. This study's projected total EE will be used as an input source for the determination of enviro-economic metrics.  
Table 6 shows the MSS's CO\({}_{2}\), SO\({}_{2}\), and NO emissions in tonnes, as well as the amount of carbon credits gained in US dollars. The MSS is estimated to release 219.62 kg of CO\({}_{2}\), 1.67 kg of SO\({}_{2}\), and 0.69 kg of NO throughout its lifetime. For ten years of life duration, the net CO\({}_{2}\) mitigation from the MSS was 2.09 tonnes. Carbon credit is a straightforward translation of the net amount of CO\({}_{2}\) reduced to the economic value. The amount of carbon credits obtained for reducing CO\({}_{2}\) by 2.09 tonnes was USD 20.94. The reason behind the poor carbon credit and net CO\({}_{2}\) reduction obtained was that the desalination system required a large amount of embodied energy; 86.64 kWh was utilized by the galvanized iron. Finally, it is suggested that constituents with lower EE values should be used to reduce the emissions of SO\({}_{2}\), CO\({}_{2}\), and NO, boost the carbon credits, and enhance the value of net CO\({}_{2}\) reduction.