Development of UV/Persulfate based laboratory-scale continuous-flow leachate treatment system

Stabilized landfill leachates (SLL) contain a high concentration of biorecalcitrant substances. Conventional biological-based water treatment methods are often inefficient in the treatment of SLL. In this study, a laboratory-scale automated continuous flow leachate treatment system was developed to study the feasibility of combining coagulation-flocculation and a sulfate radical-based advanced oxidation process (UVactivated persulfate) in the treatment of SLL. SLL was first treated with coagulation- flocculation. Subsequently, the pre-treated leachate was filtered through a sand filter into an ammonia-stripping tank and a flow-through UV purifier. Ammonia stripping and the UV-activated persulfate advanced oxidation process were performed simultaneously to remove ammonium ions and dissolved organic matter from the pre-treated SLL. The treated SLL was then passed through an anion exchange column for sulfate ion removal. The results showed that this system reduced chemical oxygen demand and total organic carbon concentrations by 91 and 90%, respectively. Further, 68% of ammoniacal nitrogen was removed. The color and turbidity of the SLL were removed entirely, and the system removed 70 to 98% of the metals commonly contained in SLLs. The phytotoxicity and ecotoxicity of the SLL were also largely reduced. The results confirmed that the developed continuous flow leachate treatment system could efficiently reduce the color, chemical oxygen demand, total organic carbon, metals, ammoniacal nitrogen, and the toxicity of SLL. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

A laboratory-scale automated continuous flow leachate treatment system was developed in this study, combining coagulation-flocculation and UV-activated persulfate advanced oxidation process to efficiently reduce color, chemical oxygen demand, total organic carbon, metals, and toxicity of stabilized landfill leachates (SLL).