Sewage sludge contains lots of valuable elements which are prized as fertiliser for use in agriculture. Phosphorus in particular is an important nutrient for plants. Researchers at Landshut University of Applied Sciences are therefore looking at ways in which wastewater treatment facilities can use sewage sludge effectively, particularly in rural areas. They are doing this in conjunction with partners based in the Czech Republic.
The sludge that settles in sedimentation tanks is full of valuable substances like phosphorus, nitrogen or potassium. For this reason, it is often used in agriculture as fertiliser on fields. However, the sewage sludge also often contains contaminants which are harmful to the environment and health such as microplastics, heavy metals like copper or zinc, hormone disrupters such as plasticisers, or pharmaceutical residues.
According to the coalition agreement between the parties of the German federal government, spreading sewage sludge as fertiliser is to be discontinued and instead the compounds containing phosphorus are to be recovered for subsequent use in fertilisers.
Recovering phosphates from sewage sludge
"Phosphorus is a finite resource and easily accessible reserves are expected to be depleted in the next 80 to 120 years. German wastewater potentially contains around 70,000 tonnes of phosphorus which could be recovered each year, whereas Germany alone consumes some 120,000 tonnes per year," explains Prof. Diana Hehenberger-Risse from the Technology Centre for Energy at Landshut University of Applied Sciences.
It is now mandatory for large wastewater treatment plants to recycle phosphorus. This could also make ecological sense for smaller facilities. However, according to Hehenberger-Risse, "The modifications required to recover phosphates are technically complex and require massive investment on the part of smaller sewage plants. To make it worthwhile and ensure that sewage charges don't skyrocket, municipal authorities need to cooperate and find a joint solution."
To find out what that could be, the environmental scientist is working on a research project known as greenIKK. Partners on the project include her colleague at Landshut, the chemist Prof. Josef Hofmann, IKOM Stiftland (a special purpose association) and the Czech Forestry and Game Management Research Institute. The Landshut faculties for Mechanical Engineering and Interdisciplinary Studies also participate substantially in the project. Together their objective is to use sewage sludge effectively. "This reduces the emission of greenhouse gases and increases resource efficiency," says Hehenberger-Risse. The project is scheduled to run until the end of 2019 and is being financed by the European Regional Development Fund.
The objective: to use sewage sludge effectively
The researchers are focusing on the district of Tirschenreuth in Bavaria and the neighbouring region of Tachov/Cheb in Czechia. "Among other things, we are looking at how to recover phosphorus, nitrogen and trace elements from wastewater and sewage sludge in a commercially and ecologically viable way," explains Hofmann. "Our Czech partners are assisting us with chemical analysis. As well as measuring the phosphorus content, they will be determining its quality as a fertiliser, i.e. how easily plants can utilise it."
Often some of the sewage sludge from facilities is dried and incinerated. Phosphorus can also be extracted from the ash. A complex process of drying is necessary to ensure that the sludge burns readily. "That requires a lot of energy," says Hehenberger-Risse. With the project partners she therefore wishes to test whether wastewater treatment plants can use solar power for drying purposes and if so which ones. They are also exploring whether it makes sense for plant operators to join forces and dry sludge from various local authorities at central facilities.
Small wastewater treatment plants need to be both ecologically and economically sound
"To date, there have only been studies about disposing of sewage sludge and which deal with some aspects of specific wastewater treatment sites, towns, cities or administrative districts. This project is designed to consider methods of disposal and related options by taking an integrated, holistic approach," says Hehenberger-Risse in summary. At the end of the project, she and her colleagues will draw up recommendations for action enabling participating authorities in Germany and the Czech Republic to make good, common use of sewage sludge across borders from both an ecological and economic perspective. According to Hehenberger-Risse, "This can then likewise benefit other communities in neighbouring regions."
Ulrike Schnyder | idw - Informationsdienst Wissenschaft
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
25.08.2017 | Physics and Astronomy
25.08.2017 | Health and Medicine
25.08.2017 | Earth Sciences