Comprehensive evaluation of chemicals in residual and condensate during landfill leachate evaporation

This study evaluated the trends of 44 water quality parameters by using a bench-scale rotary evaporator to evaporate three landfill leachates and two synthetic leachates. The concentrations of total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), total organic carbon (TOC), five-day biochemical oxygen demand (BOD₅), zinc, chromium, and most per- and polyfluoroalkyl substances (PFAS), including fluorotelomer sulfonates (FTSs), perfluoroalkyl carboxylic acids (PFCAs), and perfluorosulfonic acids (PFSAs), increased in all three landfill leachate residuals during evaporation. On the contrary, the concentrations of volatile compounds including ammonia, naphthalene, p-cresol, pyridine, and fluorotelomer alcohols (FTOHs) decreased in the residuals. Ammonia was first transferred to the condensates and then to the vapor phase. All naphthalene was transferred to the vapor phase. The majority of p-cresol (81-93 % in mass) was transferred to the condensates. Pyridine ended in both the vapor phase (21-53 % in mass) and the condensates (47-79 % in mass). Aniline and phenol were produced during the evaporation. More than 99.9 % of each FTOH in mass was removed from the residual and condensate. PFCAs mainly remained in the leachate residual, with only 0.138-6.83 % (in mass) of PFCAs transferred to condensate.