Organic Micro-pollutants are low and trace levels of synthetic organic substances released in water through human activity. They can be found in industrial, agricultural and domestic wastewater streams. Some of the most difficult-to-treat wastewater contains micro-pollutants such as persistent organic pollutants (POPs), herbicides and pesticides, personal care products (PCPs), toxic chemicals, carcinogenic and endocrine disruptive compounds (EDCs), and emerging contaminants.
The EU's recommendation to remove micro-pollutants
Increasingly sensitive analytical techniques are enabling regulators to identify the presence of micro-pollutants in water and wastewater. Micro-pollutants can enter water streams via the inadequately treated effluents from wastewater treatment plants (WWTPs), causing detrimental effects to the aquatic environment and posing a danger to human health, even at concentrations of micrograms or nanograms per litre. These organic substances can be active pharmaceutical ingredients (APIs), biocidal compounds, food additives, cosmetic ingredients, detergents and hormones, each of them highly toxic and hard-to-treat via popular technologies such as membranes, GAC or filters.
Safe discharge to the environment
The levels of micro-pollutants acceptable for disposal to sewers and the environment are determined by Environmental Quality Standards and disseminated through regulation, for example the EU's Water Framework Directive, the US' Clean Waters Act and the guidelines of the Ministry of Environmental Protection in China. Besides the current outlook on contaminants, regulations are changing to include various emerging contaminants, which have previously remained off their radar. The dynamics of global water safety poses an additional challenge to industry and municipal WWTPs. They need to future-proof their technologies in order to meet stricter discharge requirements.
Treatment of micro-pollutants in waste water
There is a growing global trend towards point-of-source treatment of wastewater before it is mixed with other waste streams at municipal treatment facilities. Thus, hard to treat micro-pollutants can be removed before they reach municipal treatment facilities. Since micro-pollutants in wastewater survive primary and secondary treatment stages, advanced or tertiary treatments can be implemented to increase technology efficacy. Tertiary technologies comprise the final, polishing treatment stage that allows for safe wastewater disposal or water reuse and zero liquid discharge (ZLD).
Advanced oxidation is one well-known method of tertiary treatment. It reduces organic micro-pollutants to satisfactory concentrations, yet typically generates breakdown products that can be more dangerous than the initial chemicals. The high energy consumption that is characteristic of advanced oxidation doesn't make it suitable for the treatment of trace concentrations of micro-pollutants in wastewater.
Arvia's novel solution
The Arvia ODC treats problem pollutants in wastewater by combining advanced oxidation and adsorption in a single unit. The system uses a unique adsorbent, NyexTM, which glues organic micro-pollutants to its surface. When an electric current is applied across the two electrodes surrounding the Nyex, oxidation occurs throughout the entire unit, rather than just on the electrodes' surface, as is typical of electrochemical cells. The oxidation of the adsorbed contaminants and the regeneration of the Nyex happen simultaneously, allowing for a continuous process. As a result, the energy used for oxidation is proportional to the amount of organic to be treated, rather than the volume of waste water. Therefore, the Arvia ODC system is ideal for removal of organic pollutants at low concentrations, including at ppb level. Moreover, the system uses no chemicals and creates no by-products or secondary waste stream. It is fully-scalable and can address any flow rates in most applications.
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