Innovation in wastewater treatment: sustainable solutions for a resilient future
Densely populated cities face enormous challenges in managing wastewater due to increasing water demand and climate change. The need for solutions that are more innovative than conventional methods has become urgent. In this context, companies like Tedagua are leading the way towards sustainability and efficiency with advanced technologies such as AnMBR, methanation, and electrodialysis.
Densely populated cities are facing a critical situation when it comes to the management of their wastewater. Rapid urban growth, coupled with increased domestic and industrial activities, has overburdened existing wastewater treatment systems, leading to a number of worrying environmental and demographic consequences.
First, improper wastewater management directly contaminates water sources, such as rivers, lakes, and aquifers. Untreated or poorly treated discharges introduce harmful pollutants such as pathogens, excess nutrients, and hazardous chemical compounds into aquatic ecosystems. Not only does this harm aquatic life and deteriorate water quality, but it also poses a significant risk to public health, especially in areas where communities rely on surface water sources for consumption.
In addition to environmental impacts, poor wastewater management also poses significant demographic challenges. Water stress, exacerbated by climate change and increased demand, is forcing cities to look for alternative solutions for drinking water supply. The reuse of treated wastewater, while still presenting technical and societal challenges, is becoming an increasingly viable option to relieve pressure on natural water resources.
To address these challenges effectively, a comprehensive approach is required that combines innovative solutions with urgent action. There is a need for more efficient and sustainable wastewater treatment technologies that can reduce the environmental footprint of the process and recover valuable resources such as energy, reusable water, and nutrients.
Densely populated cities face enormous challenges in wastewater management due to increasing water demand and climate change
At the national level, Spain has made efforts to comply with European requirements in terms of wastewater treatment; this is reflected in the National Plan for Purification, Sanitation, Efficiency, Savings and Reuse. This comprehensive plan aims to improve infrastructure and promote innovation in the wastewater treatment industry to comply with EU directives and protect the environment and public health.
At a European level, EU targets have been set to minimise the environmental impact of the wastewater treatment sector and make it energy-neutral. This includes reducing energy consumption, promoting water reuse, and biogas production. This approach will ensure Europe's energy and environmental sustainability.
Projects such as "From Waste to Resources: From WWTP to Biofactory" are turning the challenges of wastewater treatment into opportunities. These initiatives aim to research and develop advanced technologies for nutrient recovery and energy production from organic waste, along with water regeneration, thus showing the potential transformative effect that innovative solutions can have on the sector.
One of the most promising technologies in this context is the application of anaerobic membrane bioreactors (AnMBR). Not only will they enable the effective treatment of water that is sent to the environment, but they will also enable the generation of biogas as a by-product, which is considerable in terms of renewable energy. AnMBRs use microorganisms in an oxygen-free environment to break down organic compounds in wastewater.
Anaerobic membrane bioreactors enable effective treatment and biogas generation, improving effluent quality and separation efficiency
The main advantage of these systems is that they produce biogas, which is mainly composed of methane and can therefore be used as an alternative source of energy. In turn, using membranes instead of traditional decanters in these systems improves effluent quality and the efficiency of the separation process. Membranes allow for more precise and effective separation of solids and microorganisms from the treated water, resulting in higher quality effluent. In addition, membranes can retain microorganisms in the reactor for longer, improving the degradation of organic compounds and biogas production. This makes it possible for membrane bioreactors to operate at up to 50% higher biomass concentrations, resulting in a significant increase in the treatment rate and overall system efficiency.
However, the application of AnMBR systems also presents its challenges. They require a high organic load in influent wastewater to function effectively, limiting their suitability for certain situations. Integrating anaerobic membrane bioreactors with other pre-treated solid waste treatments would result in an integrated solution to address multiple waste streams and optimize efficiency in biogas production.
Another significant limitation is the low removal of nutrients such as nitrogen and phosphorus. Under anaerobic conditions, AnMBR converts organic nitrogen to ammonium, but does not perform the nitrification and denitrification processes necessary to remove nitrogen. In addition, it does not favour the biological elimination of phosphorus, which requires alternating aerobic and anaerobic conditions.
These nutrients can cause significant environmental problems, such as the eutrophication of water bodies. Eutrophication occurs when excess nutrients, primarily nitrogen and phosphorus, cause uncontrolled algae growth, depleting oxygen in the water and negatively affecting aquatic life. The recovery of these nutrients not only helps mitigate these environmental impacts, but also allows them to be reused in agriculture as fertilizers, promoting a circular economy.
Electrodialysis emerges as one of the most innovative methods for the recovery of ammonium and phosphate ions in soluble form
Electrodialysis emerges as one of the most innovative methods for the recovery of ammonium and phosphate ions in soluble form. This process uses selective membranes and an electric field to selectively transport specific ions across them. Thus, only the desired ions, such as ammonium and phosphate in this context, can be removed by passing through the membranes in a concentrated stream. On the other hand, chemical precipitation is a process in which chemical reagents are added to wastewater to promote the formation of insoluble solid compounds, known as precipitates. In the case of the recovery of ammonium and phosphate ions, certain chemical reagents are added that react with these ions to form solid precipitates. These precipitates can then be separated from the wastewater, thus allowing the recovery of the ions of interest and being able to have agricultural uses.
With the transition to cheap renewable energy in wastewater treatment plants, the usefulness of the biogas produced may decrease if a suitable application is not found. Converting biogas to biomethane for injection into the natural gas grid is an efficient solution. Injecting biomethane into the natural gas network not only provides an efficient solution for the management of the biogas generated, but also contributes significantly to energy sustainability and carbon footprint reduction. This approach makes it possible to integrate renewable energies into the existing energy system, maximizing the use of available infrastructure and resources.
Methanation is a novel technology by which biogas is converted into high-purity biomethane using hydrogen in the Sabatier reaction. Using process intensification, multi-channel minireactors offer advantages compared to conventional fixed-bed reactors, such as better mass transfer, avoiding the formation of hot spots, and an increase in throughput of 10 to 20%.
On the other hand, the porous membranes used in AnMBR allow for the retention of suspended solids and some pathogens but are not effective against emerging contaminants such as microplastics, pesticides, and pharmaceuticals, which are of high concern in water reuse. These contaminants of emerging concern (CECs) represent a critical public health and environmental issue and can adversely affect aquatic life and eventually enter the human food chain. There is an urgent need for technologies capable of completely removing these pollutants from wastewater before they are safely discharged into the environment.
There is a need for efficient wastewater treatment technologies that can reduce the environmental footprint and recover valuable resources
In a significant development, the European Council and Parliament reached a provisional agreement on the revised proposal of 26 October 2022 for a directive on urban wastewater treatment (COM(2022) 541 final) on January 29, 2024. In a novel approach, this directive mandates novel treatment requirements specifically targeting these CECs. To ensure effectiveness, a minimum 80% removal rate will be required for six indicator substances from a list of thirteen listed in Annex I, Table 3 Note 1 of the Directive.
Annex I, Table 3 Note 1 of the UWWT Directive proposal
In close collaboration with universities, research centres and technology companies, Tedagua develops and transfers these emerging technologies to meet the specific demands of cities. This encompasses technology assessment, pilot testing, and process optimization to make delivery more effective and feasible.
For the implementation and operation of wastewater treatment systems, Tedagua has the expertise and infrastructure necessary to integrate these emerging technologies. Ensuring the efficiency and sustainability of these facilities, from the conception and construction to the continuous management of the treatment plants.
These new technologies mean that wastewater treatment can go in a much more sustainable and effective direction. This is because they offer innovative solutions to the current water management challenges faced by large cities. Its study and future development predict a future for a more resilient and environmentally friendly planet. Innovations and multidisciplinary approaches are helping to restore water resources and environmental health in cities, highlighting once again Tedagua's commitment to being innovative and offering solutions to new water treatment challenges.