# Evaluation of the Coupling of a Hybrid Power Plant with a Water Generation System
## 3 Simulations
### Wastewater Treatment Plant  
Part of the electricity generated in the HPP is used to run the proposed WWTP that aims to provide the region with drinking water. The wastewater treatment train is shown in Figure 2. Wastewater is collected and guided towards the treatment plant, where it undergoes a series of physical, biological and chemical procedures during the first stage of the purification process. First, primary settling takes place eliminating any suspended solids using gravity, enhanced by the action of coagulants and flocculants [32]. Then, a membrane bioreactor removes organic and nitrogen constituents of wastewater [50]. On the completion of these treatments, the water is put in waste stabilization ponds for about 3-4 days, where pathogenic microorganisms and certain nutrients are removed by means of natural procedures.  
After these conventional procedures, more advanced operations are required to fulfill the established water quality requirements suitable for human consumption. These include ozone disinfection for bacteria and viruses inactivation, as well as algae control [53]. In the next step, Biological and Granular Activated Carbon (BAC & GAC) polish water by means of several filters that remove as much organic load as possible [54]. Then, reverse osmosis (RO) reduces disinfection byproducts, salt concentration and removal of dissolved organic carbon [55]. Ultraviolet radiation constitutes an effective key stage against multiple pathogens and other bacterial illnesses. Chlorination dosage is the final disinfection barrier for the ultimate inactivation of pathogens [56]. Finally, the purified water is returned to the potable supply system without the need for an environmental buffer. It is assumed that the plant is operated and closely monitored to avoid failures within the different disinfection stages. In the event of an error, the water is rejected or recirculated to the beginning of the treatment train.  
\begin{table}
\begin{tabular}{|l|} \hline
**AmbientAir** \\ \hline
20 °C, 1 bar, 80\% relative humidity \\ Composition (mol\%): N\({}_{2}\) (77.3), O\({}_{2}\) (20.73), CO\({}_{2}\) (0.03), H\({}_{2}\)O (1.01), Ar (0.93) \\ \hline
**Fuel** \\ \hline
3.52 kg/s, 20 °C, 1.029 bar, LHV=16.4 MJ/kg \\ Olive pomace composition (mol\%): C (52.5), O (39.53), H (7.1), N (0.8), S (0.07) \\ \hline
**Biomass Auxiliary System** \\ \hline Compressor: isentropic efficiency: 85.0\%, mechanical efficiency: 99.0\%, pressure ratio: 1.03 \\ \hline
**Steam Cycle** \\ \hline HRSG: 1 reheat stage, 1-pressure-level: 1.007 bar \\ HRSG pressure drop: hot side: 7 mbar, cold side: 2\% \\ SH, ECON: ATmin: 20 °C, SH steam pressure: 126 bar \\ EVAP: approach temperature: 276 °C, ATpinch-point: 5 K, saturation pressure: 133.28 bar \\ Live steam temperature: 545 °C \\ Steam turbine isentropic efficiency: HP (86.0\%), IP (86.0\%), LP (82.0\%) \\ Condenser operating pressure: 0.1 bar \\ Pumps: efficiency 80.0\% (incl. motors and mechanical efficiency: 99.8\%) \\ Cooling water temperature: 20 °C \\ \hline \end{tabular}
\end{table}
Table 1: Power block operational parameters.  
Figure 2: Wastewater treatment train.