Application of non-acid stripping solution in hydrophobic membrane process for high-purity ammonia recovery from high-strength ammonium wastewater

Recently, resource recovery from wastewater has been in the spotlight due to climate change and the energy crisis. Ammonia has significant value as a resource that serves as fertilizer or eco-friendly fuel, with a market value ranging from $0.4 to $1.0 per kg-N. In the membrane contactor (MC) process, an acid stripping solution such as H₂SO₄ is generally used for high ammonia recovery efficiency. However, the ammonia-recovered stripping solution often has limited applications as fertilizer due to the presence of anions, necessitating costly downstream processes like electrochemical treatments to separate ammonia from these contaminants. This study introduces a novel approach that dynamically compares various stripping solutions to reduce chemical consumption while achieving high-purity ammonia recovery. Notably, the recovered ammonia from the membrane contactor showed no detectable levels of nitrate, other ions, or organic carbon, all without the use of acidic solutions. Furthermore, the benefit-cost ratio of 1.42, derived from the dynamic comparison, highlights the cost-effectiveness and demonstrates the practicality of this method compared to traditional acidic stripping approaches. This innovative comparison underscores the membrane contactor system's ability to recover high-purity ammonia, presenting a sustainable and economically viable solution for ammonia recovery in wastewater treatment. It achieves this without the need for additional chemical agents or expensive downstream processes, offering a more efficient alternative to conventional methods.