Electrochemical ammonia recovery and co-production of chemicals from manure wastewater

Livestock manure wastewater, containing high level of ammonia, is a major
source of water contamination, posing serious threats to aquatic
ecosystems. Because ammonia is an important nitrogen fertilizer,
efficiently recovering ammonia from manure wastewater would have multiple
sustainability gains from both the pollution control and the resource
recovery perspectives. Here, we develop an electrochemical strategy to
achieve this goal by using an ion-selective potassium nickel
hexacyanoferrate (KNiHCF) electrode as a mediator. The KNiHCF electrode
spontaneously oxidizes organic matter and uptakes ammonium ions (NH₄⁺) and
potassium ions (K⁺) in manure wastewater with a nutrient selectivity of
~100%. Subsequently, nitrogen- and potassium-rich fertilizers are produced
alongside the electrosynthesis of H₂ (green fuel) or H₂O₂ (disinfectant)
while regenerating the KNiHCF electrode. The preliminary techno-economic
analysis indicates that the proposed strategy has notable economic
potential and environmental benefits. 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.