Wastewater treatment is one of the key parts in the transition to a zero-waste circular economy. One of the challenges after water is purified is disposing of excess organic matter called sludge. This sludge is concentrated, dehydrated, sanitized, and used for agricultural fertilizer and forest soil regeneration. In some cases, incineration is used. However, there are ways to optimize performance, especially in the biogas sector. One of them is the research and development project “DIGEST-UP”, which uses substances such as ammonium contained in sludge to promote the metabolism of sludge that is difficult to reduce, such as secondary sludge.
The DIGEST-UP technology approach opts for pretreatment of this secondary sludge by utilizing the ammonia-rich electric current produced in the plant itself to improve environmental, energy and economic efficiency. In addition to reducing the total amount of sludge, this process increases biogas production.
The pilot plant designed within the project is currently housed at the Wastewater Treatment Plant (WWTP) of Arroyo Clebro Cuenca Media Alta in Pinto (Madrid). This experiment has shown promising results. The daily production of biogas increased by 22% to 44% depending on the initial concentration of ammonium, and the production of methane also he increased by 32%.
Biogas, a versatile raw material
The gas obtained can be used as fuel for electric cogeneration. This means it can generate a portion of the energy your wastewater treatment plant consumes, making it more sustainable. Furthermore, with the application of a refining process, this biogas can be used as natural gas for domestic or industrial use, or as fuel for automobiles. Ultimately, its use, whether refined or pristine, contributes to reducing our carbon footprint, providing yet another tool in the fight against global warming.
DIGEST-UP, an ACCIONA initiative funded by the Center for Industrial Technology Development (CDTI), Ministry of Science, Innovation and Universities, is versatile enough to work with any type of sewage treatment plant, including anaerobic sludge. It is a technology with digestion. This technology is applicable to both existing and new generation plants.
Other solutions for wastewater challenges
In addition to DIGEST-UP, other alternatives are being considered to optimize wastewater treatment. One example is Life CELSIUS, which uses anammox bacteria to convert nitrogen dissolved in water into nitrogen gas, which is released into the atmosphere. This project will reduce the need for wastewater aeration, an energy-intensive process.
It may surprise you, but to make the whole process more sustainable on a global scale, and to get other resources from this water purification, there are alternatives to getting fertilizer from ammonium. Optimized to reduce plant energy consumption. So researchers at Aalto University in Finland have developed a method to purify urine. Their approach is based on calcium hydroxide, which raises the PH of water to yield gaseous ammonia, the raw material used to make fertilizers. In the same process, calcium salts are used to precipitate phosphorus, which is also used as a fertilizer.
The main goal for next year is to transition to renewable energy and obtain useful and non-polluting by-products for the eco-friendly water cycle.
sauce: action
