The Wastewater Treatment Plant in Thailand plays a vital role in treating raw domestic wastewater. As the demand for treating wastewater grows, the energy requirements associated with treatment processes become essential. This study aims to identify energy-intensive areas in wastewater treatment plants and provide inventory data for the indirect environmental impact. It also determines the suitable opportunities to recover energy from wastewater treatment plants. The water-energy nexus was examined through Material Flow Analysis (MFA) using Substance Flow Analysis (STAN) Software. The wastewater treatment plant is extended to produce water for reuse. System allocation is adopted to separate the treated wastewater and reuse water products. In Thailand, the aeration tank unit is the most energy-intensive. This condition can be explained by operating the aeration tank, which accounts for 33.87% of the total energy demand. The research found that around 0.155 kWh/m3 is needed for treating raw domestic wastewater to meet the effluent standard. The extended treatment for converting the raw wastewater into reuse water requires 0.3286 kWh/m3. Reuse water is beneficial for providing sustainable water resources but requires a 112% energy increase. The plant relies on Thailand’s EGAT Energy Mix (58.09% Natural Gas, 29.01% Lignite, 10.21% Hydropower, 2.52% Diesel, 0.16% Fuel Oil, 0.002% Geothermal Energy and 0.008% remain unidentified). Rather than fully relying on Thailand EGAT, the research suggests renewable energy installations and nutrient recovery options. Solar panels and micro-hydro power generation are promising ideas to install. Moreover, recovering the nutrients from wastewater can address environmental problems and offer valuable resources simultaneously. The findings of this Study provide profound benefits for developing sustainability in wastewater treatment plants.
