Case Study: Boron-Doped Diamond Electrodes Revolutionize Oily Wastewater Treatment
Introduction
The proper treatment of oily wastewater is a pressing environmental concern, stemming from diverse industrial processes such as petroleum refineries, oil storage and transport, petrochemical facilities, oil drilling, and contaminated site remediation. The discharge of large volumes of effluents from these sources into ecosystems daily poses a significant challenge due to the hazardous and refractory nature of oily wastewater. This case study explores the groundbreaking application of boron-doped diamond (BDD) electrodes through electrochemical oxidation as an advanced and effective solution for the treatment of oily wastewater.
Oily Wastewater Treatment: Materials and Methods
The study, conducted at the Foxconn manufacturing site, aimed to address the challenges associated with oily wastewater treatment. Optimal operating conditions were identified to achieve efficient oxidation while minimizing energy consumption. The focus was on enhancing the removal of residual pollutants post-treatment, recognizing the need for modifications at existing wastewater treatment facilities.
Advanced oxidation processes (AOPs) emerged as a promising avenue for treating oily wastewater, offering rapid reaction rates, freedom from secondary pollution, pathogen inactivation, and potential complete mineralization of pollutants into innocuous byproducts. AOPs, particularly electrochemical oxidation using boron-doped diamond electrodes, proved to be a versatile, easily applicable, and safe treatment method, generating highly reactive oxygen species, primarily hydroxyl radicals (•OH), known for their low selectivity in oxidizing pollutants.
Boron-Doped Diamond Electrochemical Oxidation
The boron-doped diamond (BDD) electrode has demonstrated innovation and efficiency in treating oily wastewater. Anodic oxidation with the BDD electrode generates hydroxyl radicals (•OH) through water oxidation, directly oxidizing pollutants at the electrode’s surface and interface. At higher current densities, ions and water molecules electrochemically react with •OH or directly on the BDD surface, producing intermediary radicals such as hypochlorous acid, peroxydisulfuric acid, hydrogen peroxide, and ozone.
Comparative studies revealed that BDD electrodes achieved 12 times higher oxidation rates for phenol and chemical oxygen demand (COD) compared to a ruthenium mixed metal oxide (MMO) electrode, even at four times lower current density. This exceptional •OH generation and oxidation rates are attributed to the low •OH adsorption enthalpy of BDD electrodes.
Boron-doped diamond/BDD electrode has proven to be an innovative and efficient solution for treating oily wastewater. Anodic oxidation with BDD electrode generates hydroxyl radicals (•OH) through water oxidation, rather than oxygen evolution. These •OH radicals directly oxidize pollutants at the electrode’s surface and interface, a process referred to as direct oxidation. At higher current densities, ions and water molecules electrochemically react with •OH or directly on the BDD surface, producing intermediary radicals such as hypochlorous acid, peroxydisulfuric acid, hydrogen peroxide, and ozone.
The exceptional •OH generation and oxidation rates exhibited by BDD electrodes are attributed to their low •OH adsorption enthalpy. In comparative studies, it was found that BDD electrodes achieved 12 times higher oxidation rates for phenol and chemical oxygen demand (COD) compared to a ruthenium mixed metal oxide (MMO) electrode, even at four times lower current density.
Key Data From Foxconn Manufacturing Site
Sampling & Analysis
- BDD Area: 8 square meters
- Influent COD: 10,000-11,000 mg/L
- Effluent COD: <300 mg/L
Project Cost & Energy Consumption
- Electricity Fee: 50-60 CNY/metric ton
- Energy Consumption: 90-120 KWh/metric ton
Handling Capacity
- Current Handling Capacity during Test: 9 metric tons per day
- Estimated Handling Capacity in Full Operation: 15 metric tons per day
In conclusion, the treatment of oily wastewater is an environmental imperative, and the utilization of boron-doped diamond (BDD) electrodes via electrochemical oxidation represents a transformative solution. BDD electrodes offer exceptional hydroxyl radical (•OH) generation and oxidation rates, effectively addressing the challenges posed by the hazardous and refractory nature of oily wastewater.
While further optimization is required to minimize energy consumption, BDD electrochemical oxidation stands as a beacon of hope in the effort to mitigate the adverse impacts of oily wastewater on our environment and society. As a leader in oily wastewater treatment, Boromond has developed customized BDD test modules, resulting in the assembly of BDD pilot modules that provide stringent control over energy consumption, waste management, heat utilization, and real-time monitoring.
BDD electrochemical oxidation represents a highly promising technology for the treatment of oily wastewater. It enables the generation of extremely reactive oxygen species, facilitating the mineralization of hazardous, refractory, and toxic pollutants present in complex industrial effluents and oil spills, all without undesirable byproducts.
By offering an environmentally compatible treatment method utilizing simple electrolytes, BDD electrochemical cells contribute significantly to mitigating the substantial impacts of oily wastewater discharges into natural ecosystems. Although optimization is required to minimize energy consumption, this advanced process holds immense potential for the removal of oil from water.
Boromond, as a leading supplier in the field of oily wastewater treatment, has developed customized BDD test modules to conduct multiple on-site tests. These tests have culminated in the assembly of BDD pilot modules, allowing for stringent control over energy consumption, waste management, heat utilization, and real-time monitoring.
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