A comparative study of hydrogen peroxide oxidation and electrocoagulation using aluminum, iron, and zinc electrodes for urban sludge disintegration

ABSTRACT

Municipal and industrial wastewater treatment plants produce large amounts of sludge containing high levels of organic, chemical, and microbial pollutants. Unless stabilized completely and discharged safely, they may become potential pollution sources threatening soil and water bodies. This study investigated H₂O₂ oxidation and electrocoagulation as pretreatments to improve stabilization of an urban sludge. The H₂O₂ oxidation was optimized with respect to H₂O₂ dosage and initial sludge pH-H₂O₂. Batch electrocoagulation experiments were conducted using aluminum, iron, and zinc electrodes to investigate the effect of treatment period, current density, and pH. The effectiveness was compared in terms of solubilization of sludge, disintegration degree, and reduction of total solids. Sludge settling velocity after disintegration by both H₂O₂ oxidation and electrocoagulation were measured with respect to the operating conditions. The obtained results indicated that the high rate of sludge disintegration (63.3%) was obtained with aluminum electrodes, which has lower operating costs than iron and zinc electrodes. The H₂O₂ oxidation reached a maximum disintegration degree of 50%. Additionally, with aluminum and iron electrodes, sludge settleability was enhanced with both H₂O₂ oxidation and electrocoagulation.

KEYWORDS:

• Urban sludge
• disintegration
• H₂O₂
• electrocoagulation
• sludge settleability
• energy consumption

Acknowledgments

Acknowledgment to express for Nessark Zineb (head of laboratory) and all the staff of the wastewater treatment plant ‘Lallelick’ Annaba.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Statement of novelty

I declare that the theme is new. The disintegration of wastewater sludge by H₂O₂ was addressed alone. The application of electrocoagulation for the disintegration of sewage sludge is new. There are only two publications in this field, the difference with our work is to apply different electrode materials (Al, Fe and Zn) with the follow-up of several parameters such as: the degree of disintegration, COD, dry matter, sludge settling but also the calculation of the energy consumed for electrocoagulation method. Finally, a comparative table with the other disintegration techniques was given.

Additional information

Funding

This work was supported by the Ministry of Higher Education and Scientific Research (Algeria) (Project of research No. E0112).