Innovation and sustainability: Generating energy from wastewater

For all cities in the world, the sewage water They represent a considerable problem that must be managed appropriately. Wastewater treatment plants are implemented with the purpose of removing pollutants before discharging them back into the environment.

However, for a few years now, methods and technologies have been explored that not only seek to purify water, but also converting waste into energy, taking advantage of the energy potential that these waters contain.

What is wastewater?

The sewage water Wastewater is water that has been used for domestic, industrial or agricultural activities and that contains waste and pollutants. This water is classified as domestic, industrial and rainwater, depending on its origin. As a whole, it is a considerable environmental problem due to the pollutants it contains and its impact on the environment if it is not treated properly. For cities, the treatment of this water is crucial, but in addition to cleaning it, there is the potential to obtain energy from it.

Energy generation from wastewater

In recent years, technology has advanced significantly, allowing sewage water not only be treated, but also be used to produce energy. The most popular methods for generating energy from this waste include:

• Obtaining biogas from the decomposition of organic matter present in wastewater.
• Generation electricity by means of microbial fuel cells.
• Thermal utilization from the heat of waste water for air conditioning.
• Production of hydrogen, a clean source of energy.

Utilization of biogas

One of the most common methods is the production of biogas from wastewater. This biogas is obtained through a process called methanization, in which organic matter present in wastewater decomposes in an oxygen-free environment (anaerobic).

The main product of this decomposition is methane, which can be used as an energy source for various purposes, including electricity generation and heating.

Methane has several uses, including producing electricity by burning it in turbines or heating buildings. In several cities such as Grenoble o Strasbourg, biogas has been injected into the natural gas distribution network, providing energy to both homes and vehicles.

international experiences

There are several cities and countries in the world where wastewater is already being used to generate energy. Some examples are:

• En Basel, Switzerland, heat is recovered from wastewater for heating after the purification process. It is an example of how water treatment can also be a source of thermal energy used by the community.
• In the United StatesIn Oregon in particular, the Tri-City Water Recovery Plant has implemented a system in which methane produced by the decomposition of organic matter in wastewater is used to generate electrical and thermal energy.
• En SlovakiaProjects have also been developed for the use of wastewater in the generation of biogas.

Hydrogen production from wastewater

Another innovative method that has been the subject of research is the production of green hydrogen from wastewater. This hydrogen is generated from microbial electrolysis cells, a technology that allows obtaining high purity hydrogen using specialized bacteria that break down the organic matter present in the water. Companies such as Ingeobras are developing technologies that offer this efficient and sustainable solution.

Green hydrogen has significant potential as a clean fuel, and its production from wastewater offers a more economical and sustainable approach compared to traditional hydrogen production methods such as reforming fossil materials or conventional electrolysis. As this technology advances, it could become a key solution for decarbonizing transport and the energy industry.

Electricity generation using microorganisms

Another of the most innovative methods to take advantage of wastewater is the use of microbial fuel cellsThis method uses bacteria that metabolize organic matter in wastewater and release electrons in the process. These electrons can be captured to generate electricity directly. Microbial fuel cells are already being used in some pilot projects and have the potential to produce electricity continuously and sustainably. In addition, this process can improve the energy efficiency of treatment plants by reducing the need for expensive aeration and pumping systems.

Success stories in cities around the world

A number of successful projects have been developed in cities around the world. For example:

• En Strasbourg, it is expected to produce 1,6 million cubic meters of biomethane daily from wastewater treatment, enough to supply energy to around 5.000 homes.
• En Helsinki, FinlandThe heating and cooling plant at Katri Vala Park uses wastewater as a source of thermal energy.
• En MadridThe Wastewater Treatment Plant (EDAR Sur) has installed turbines to harness the kinetic energy of the water at its exit and produce electricity for the plant's own consumption.

Importance of continuing to develop this technology

Although there are already multiple projects underway, it is crucial to continue investing in research and development to improve the efficiency and reduce the costs of these technologies. Wastewater is not only a source of pollution, but also represents an opportunity to generate green energy, reducing the carbon footprint and moving towards a more sustainable energy model. The larger-scale implementation of these technologies can help cities become more energy self-sufficient and generate positive impacts in the fight against climate change. If wastewater is used better, we could be looking at a key solution for the global energy transition.