Construction and operation characteristics of a fully quantified low-carbon treatment process for old landfill leachate

The feasibility of utilizing a coagulation-flocculation/sedimentation-denitrification (DN)/partial nitrification (PN)-anaerobic ammonium oxidation (Anammox)-electrochemical oxidation was investigated to achieve cost-effective and fully quantified treatment of leachate from old landfills, which contains lower C/N, higher NH4+-N and refractory chemical oxygen demand (CODr). The results indicated that the coagulation-flocculation/sedimentation, which aimed to remove the CODr, not only improved the nitrogen conversion efficiencies of the following PN and Anammox by 17.5 % and 105 %, respectively, but also benefited the solid phase enrichment of PO43− and the energy consumption of subsequent advanced treatment. The optimal dose of perfluorochemical (PFC) was found to be 1200 mg/L. The optimal electrode plate spacing and current density of the electrochemical oxidation process were 25 mm and 350 A/m2, respectively, and advanced treatment of the chemical oxygen demand (COD) and total nitrogen (TN) in the wastewater was achieved within 2 h. After 190 d of operation, the effluent quality met the required discharge standards. This process has the advantage of realizing full quantified treatment of wastewater and has significant environmental benefits. [Display omitted] •A pretreatment-low carbon denitrification-advanced oxidation process was constructed.•The process realizes the full quantified treatment of the old landfill leachate.•Coagulation/precipitation reduce CODr, improve the performance of 17.5%PN and 105%An.•DN/PN/An reduces the demand for organic carbon sources nitrogen removal processes.•Electrochemical oxidation ensures the standard discharge of effluent quality index.