Advanced water treatment eliminates micropollutants and allows for water reuse
Introduction.
Our current client, a municipality located 30 km south of Gothenburg, puts pride in being at the forefront of wastewater treatment, with their keywords being “reduce, reuse, recycle”.
While Swedish wastewater treatment plants are able to purify their wastewater to a high degree, most of them still do not have an answer when it comes to treating the micropollutants present in it. This means that the treated water cannot be reused for applications where extremely pure water, such as technical water, is required.
The problem.
As mentioned previously, most municipal wastewater treatment plants are not capable of treating micropollutants such as active pharmaceutical ingredients (APIs), per- and polyfluorinated alkyl substances (PFAS), and microbial organisms. The treated wastewater is therefore not safe to use for certain purposes or in certain applications.
In addition, it is possible that treatment plants might be required to have an effective micropollutant treatment solution in the future if official regulations and guidelines are updated. At the very least, upcoming regulations for APIs will require that treatment plants have a treatment step specifically for APIs.
The solution.
To enable the reuse of treated wastewater, we at Mellifiq delivered and commissioned a modular, advanced water treatment system consisting of several individual systems. The system was placed in close proximity to the treatment plant, treating parts of the effluent flow.
The systems included in our delivery was an Ozonetech RENA Tellus system, a Water Maid FlexKarb adsorption system, and a Water Maid nanofiltration system. The RENA Tellus system and the FlexKarb adsorption system were installed and delivered in a 20 ft container while the Water Maid nanofiltration system was delivered in a 10 ft container.
Ozone treatment is the first step, and the treatment system includes functions and equipment such as oxygen generation, ozone generation, ozone dissolution, a reaction tank, piping, automation, and all necessary safety features. The Water Maid FlexKarb adsorption system follows the initial ozonation step. The FlexKarb system uses a specialized filtration media, granulated activated carbon (GAC) optimized for removing pharmaceutical substances, and also includes automation for backwashing the adsorption filter if needed. The final Water Maid nanofiltration system includes a buffer tank, prefiltration, membrane modules, piping, and automation.
Evaluation.
The project was evaluated during a period of 6 months when the system was actively in use. The evaluation period included different process scenarios and regular sampling so that we could optimize treatment efficiency and energy consumption. The results showed a 98% reduction of API substances, a >99% reduction of PFAS compounds, and a >3-log reduction in microbial activity (coliform bacteria, somaticcoliphages, and Escherichia coli).