Performance and Efficiency of Low-Temperature Atmospheric Evaporation for Advanced Treatment of Landfill Leachate Membrane Concentrate

Landfill leachate membrane concentrate (LLMC) is a high-salinity and high-organic wastewater stream that poses significant treatment challenges to conventional evaporation technologies. This study investigated the treatment performance and operating costs of a low-temperature atmospheric evaporation (LTAE) system for LLMC treatment under mild operating conditions. The effects of key operational parameters—including evaporation temperature (60–95 °C), pH (5–11), air–liquid mass ratio (A/L = 0.5–10), and concentration factor (CF = 5–20)—were systematically evaluated based on condensate quality parameters (UV254, CODCr, and NH3–N). Results demonstrated that the LTAE system achieved a higher concentration ratio (CF = 20) compared to the on-site mechanical vapor compression (MVC) system (CF ≈ 10). The optimal operating conditions for meeting effluent discharge standards were determined to be 70 °C, pH: 5, A/L = 5 and CF = 20. Under these conditions, the condensate contained ~5.6 mg/L NH3–N and ~91.6 mg/L CODCr, while the concentrate reached ~4200 mg/L NH3–N and ~38,000 mg/L CODCr, indicating that some organic matter and ammonia nitrogen escaped from the system and a gas scrubbing unit is recommended to minimize secondary pollution. Within the experimental range, the system achieved the highest KcA = 22,871.25 kW/(m3·°C) and the highest KdA reached 6.52 kg/m3·s. Economic analysis revealed a specific energy consumption of 110.5 kWh/t of freshwater produced. Despite the relatively high energy consumption, the LTAE system demonstrates considerable potential for the advanced treatment of high-organic wastewater, offering enhanced freshwater recovery under mild thermal conditions. This study provides theoretical and data support for the application of LTAE technology in LLMC treatment and similar challenging organic wastewater.