An integrated electrocoagulation-nanofiltration process for carwash wastewater reuse

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Wastewater Management

Background:

• Carwash wastewater contains pollutants that necessitate advanced treatment for reuse.
• Conventional treatment methods may not be sufficient for achieving high-quality recycled water.
• Integrated processes offer potential for enhanced pollutant removal and water recovery.

Purpose of the Study:

• To investigate an integrated electrocoagulation-nanofiltration (EC-NF) process for carwash wastewater treatment.
• To optimize electrocoagulation (EC) operating parameters for efficient pollutant removal and energy consumption.
• To evaluate the performance of different nanofiltration (NF) membranes for tertiary treatment and water reuse.

Main Methods:

• Electrocoagulation (EC) pretreatment using iron electrodes under varying temperature, stirring speed, and electrode connection modes.
• Nanofiltration (NF) of EC-treated water using NF 270 and Desal 5 DL membranes.
• Characterization of EC sludge (ESEM-EDX) and membrane fouling (FTIR, contact angle measurements); analysis of flux decline using a resistance in series model.

Main Results:

• Optimal EC conditions identified as 25°C, 250 rpm, and MP-P electrode connection for pollutant removal and energy efficiency.
• Desal 5 DL membrane demonstrated superior performance in the NF stage, achieving high removal rates for chloride (92%), conductivity (80%), and total hardness (90%).
• Membrane fouling was characterized by cake layer formation, with a low extent of fouling observed on both membranes.

Conclusions:

• The integrated EC-NF process is effective in treating carwash wastewater to a quality suitable for reuse as rinsing water.
• Optimization of EC parameters and selection of appropriate NF membranes are crucial for process efficiency.
• The study confirms the feasibility of advanced wastewater treatment for water recycling in the carwash industry.