Towards Sustainable Management of Construction Site Wastewater: A Case Study Using Electrocoagulation and Impedance Spectroscopy

Construction sites generate large volumes of contaminated wastewater, yet sustainable treatment solutions remain limited. This study presents a case study focusing on the wastewater produced from washing construction equipment at an industrial site in northern Morocco. Initial characterization revealed a chemical oxygen demand of 3125 mg O2/L, a five-day biochemical oxygen demand of 980 mg O2/L, and a total suspended solids concentration of 676 mg/L, values that exceed national discharge standards. An electrocoagulation process using aluminum electrodes was employed, alongside electrochemical impedance spectroscopy, to investigate the treatment mechanisms. Under optimal conditions (30 min at 142.85 A/m2), the removal of chemical oxygen demand reached 88%, alongside significant reductions in dissolved solids and electrical conductivity. Analysis of the electrochemical impedance spectroscopy identified two relaxation phenomena associated with ionic migration and flocculation, with efficiency decreasing beyond 0.3 A. These results demonstrate that electrocoagulation is an effective and sustainable technology for treating construction site wastewater. This study highlights its potential for practical application in the built environment and its relevance for improving the environmental performance of the construction sector.