Manure is a major source of environmental pollution and greenhouse gas emissions. It also contains a large amount of ammonia, which is a valuable nitrogen source for fertilizers and other chemicals.
However, conventional methods of ammonia recovery from manure are either energy-intensive or inefficient.
A team of researchers from the University of Wisconsin-Madison has developed a novel electrochemical process that can simultaneously recover ammonia and co-produce useful chemicals from manure wastewater.
The process uses a low-cost and scalable reactor that can operate at ambient conditions and with renewable electricity. The researchers published their findings in the journal Environmental Science & Technology.
How does the electrochemical process work?
PHILIP FONG/AFP via Getty Images
The electrochemical process consists of two electrodes immersed in manure wastewater. The anode is made of carbon cloth coated with platinum nanoparticles, while the cathode is made of carbon cloth coated with copper oxide nanoparticles.
When a voltage is applied across the electrodes, ammonia is oxidized at the anode and water is reduced at the cathode.
The ammonia oxidation produces protons and electrons, which are transferred to the cathode through the external circuit and the electrolyte, respectively.
The protons and electrons react with water at the cathode to produce hydrogen gas and hydroxide ions.
The hydroxide ions then react with the copper oxide nanoparticles to form copper hydroxide, which can be further converted into copper carbonate or other copper-based chemicals.
The electrochemical process can recover up to 99% of ammonia from manure wastewater, while co-producing hydrogen gas and copper hydroxide.
The hydrogen gas can be used as a clean fuel or a feedstock for other chemical processes, while the copper hydroxide can be used as a fungicide, a pigment, or a precursor for other copper-based chemicals.
The process also reduces the chemical oxygen demand and the total nitrogen content of the wastewater, making it easier to treat and discharge.
First, it is more energy-efficient and environmentally friendly, as it uses renewable electricity and does not generate any harmful by-products.
Second, it is more economical and profitable, as it co-produces valuable chemicals that can offset the operating costs and generate additional revenue.
Third, it is more flexible and adaptable, as it can operate under various conditions and with different types of manure.
However, the electrochemical process also faces some challenges that need to be addressed before it can be widely applied.
One of the main challenges is the fouling of the electrodes by organic matter and other impurities in the wastewater, which can reduce the performance and durability of the process.
Another challenge is the separation and purification of the products from the wastewater, which can add complexity and cost to the process.
The researchers are working on optimizing the process parameters and developing effective strategies to overcome these challenges.
The electrochemical process is a promising technology that can turn waste into wealth by recovering ammonia and co-producing chemicals from manure wastewater.
It can also contribute to the circular economy and the sustainable development of the livestock industry.
The researchers hope that their work can inspire more research and innovation in this field and pave the way for the commercialization of the process.
