Mathematical modeling of COD removal via the combined treatment of domestic wastewater and landfill leachate based on the PACT process

Abstract

The experiments performed in this study consisted of 16 batch reactors fed different mixtures of landfill leachate combined with synthetic wastewater treated using the Powdered Activated Carbon Treatment (PACT) process. The objective was to measure the COD mass removal per liter each day for each reactor using two models: the first model combined the variables PAC concentration (0 g·L⁻¹, 2 g·L⁻¹, 4 g·L⁻¹, and 6 g·L⁻¹) and leachate rate in the wastewater (0%, 2%, 5%, and 10%), and the second model combined the PAC concentration and the influent COD. The Response Surface Methodology with Central Composite Design was used to describe the response surface of both models considered in this study. Domestic wastewater was produced under controlled conditions in the laboratory where the experiments were performed. The results indicated that the PAC effect was null when the influent did not contain leachate; however, as the concentration of leachate applied to the mixture was increased, the addition of a higher PAC concentration resulted in a better COD mass removal in the reactors. The adjusted R² values of the two models were greater than 0.95, and the predicted R² values were greater than 0.93. The models may be useful for wastewater treatment companies to calculate PAC requirements in order to meet COD mass removal objectives in combined treatment.

Keywords:

• Combined treatment of landfill leachate and sewage
• powdered activated carbon treatment
• mathematical model of COD removal from leachate
• COD mass removal with PACT treatment

Acknowledgments

The authors express their gratitude to the interns from the Environmental Monitoring Laboratory I – Water and Effluents at Federal Rural University of Rio de Janeiro, and to the sanitary landfill Dois Arcos.

Funding

The authors gratefully acknowledge the financial support given by CAPES.