Electrocoagulation Sludge Valorization—A Review

Abstract

In the field of electrocoagulation (EC), various studies on pollutant removal and on the use of different EC technologies have already been made. An EC process generates sludge, which is considered waste, resulting in increased operational costs that come from waste disposal. Sludge contains valuable materials, such as the nutrients or metals removed during water purification, along with metals, such as aluminum or iron, which come from the electrodes used in an EC system. Based on the principles of circular economy or based on existing legislations, reducing the production of valuable wastes, and increasing the valorization rate of as many materials as possible are important endeavors. This study is mainly a review of the existing sludge valorization studies. This review highlights the valorization of sludge as a fertilizer (mainly as struvite), pigment, construction material (mainly as blocks), adsorbent, and catalyst. While it has already been found that EC sludge is valorizable, more studies on EC sludge valorization and on the quality of sludge produced from the effluent of EC processes are warranted.

Uncovering the potential of industrial waste: turning discarded resources into sustainable advanced materials

“…The valorisation of electroplating sludge opens avenues for its multifaceted utilization. It can serve as a fertilizer, pigment, construction material, adsorbent, catalyst, or be employed in the production of special functional materials [95,96]. Despite these opportunities, challenges and considerations in implementing electroplating sludge in material science should not be overlooked.…”

“…H. Wang et al, have actively researched to streamline pre-treatment, and reuse electroplating sludge which is in line with the circular economy, where waste becomes a resource [97]. Electroplating sludge is rich in valuable metals, so in the future this waste has the potential to be converted into high-performance materials [95]. For example, metal-organic frameworks (MOFs) synthesized from sludge can be used for efficient gas storage and separation, while biosurfactants extracted from sludge can be used in environmentally friendly cleaning products [96,98].…”

Effect of Bio-Electrochemical Treatment of Hydroponic Effluent on the Nutrient Content

“…Applying electric current and suitable pH helps to retrieve phosphorus by electrochemical means without adding chemical substances [16]. Due to lower sludge formation and lower energy demand, an iron electrode is a better solution than an aluminum one [17]. Shahedi et al [18] noted that a combination of electrocoagulation with biological treatment methods helps to remove many contaminants from effluents.…”

Electrocoagulación de iones de metales pesados en aguas residuales: Una revisión

“…(1) Los M(OH)n producidos, donde M = Fe o Al, inducen sorción, coprecipitación o atracción electrostática se-guida de la coagulación per se [22], [23] . La cantidad de lodo que precipita es reducida debido a que no se requiere el suministro adicional de químicos [24], [25] . Los iones de hierro pueden ser liberados equivalentemente desde un electrodo de acero inoxidable como ferroso (Fe 2+ ) o férrico (Fe 3+ ) [20] .…”