Electrochem method efficiently extracts wastewater ammonia

As livestock manure wastewater usually contains high ammonia levels, posing significant threats to aquatic ecosystems, scientists conducted a study to recover ammonia from wastewater efficiently.

"We got lucky because nature does a lot of the work for us," Song Jin, a UW–Madison professor of chemistry, stated according to Phys.org.

Jin added: "Manure has all this stuff in it, and we don't have to do too much extra work. The battery material goes in, and ammonia gets sucked out when the organic stuff gets oxidized."

Scientists successfully conducted the study using the KNiHCF electrode, which autonomously oxidizes organic matter and selectively captures ammonium and potassium ions from manure wastewater with nearly 100 percent nutrient selectivity. 

The study authors noted that this process results in the production of nitrogen- and potassium-rich fertilizers. Additionally, it involves the electrochemical synthesis of environmentally beneficial products like hydrogen (H2) as a green fuel or hydrogen peroxide (H2O2) as a disinfectant. 

Sustainable approach

The KNiHCF electrode regenerates in this process, allowing farmers to reuse it. 

Conventional methods of manufacturing ammonia-based fertilizers, such as the Haber-Bosch process, produce notable greenhouse gas emissions (GHGs). In contrast, this new method offers a more sustainable alternative which could potentially help lower GHGs

According to the authors, preliminary experiments using small quantities of manure yielded encouraging outcomes, recovering over 50 percent of the ammonia during the initial pass and attaining an 85 percent recovery rate after undergoing two cycles.

Furthermore, the study's environmental analyses indicated potential benefits. For instance, a 1,000-head dairy farm employing this system could reduce its ammonia emissions by more than 50 percent. Additionally, it could significantly decrease the amount of nitrate entering nearby waters, thereby demonstrating positive environmental implications.

As a result, a model dairy farm using this system could potentially generate higher revenues than operating costs, given reasonable electricity prices.

The authors stated: "This work provides a powerful strategy for efficient nutrient (NH4+ and K+) recovery and decentralized fertilizer and chemical production from manure wastewater, paving the way to sustainable agriculture."

The study was published in the journal – Nature Sustainabilityon December 8.