Effects of co-existing substances on phosphorus recovery from swine wastewater via struvite crystallization with a carbon felt cathode

Swine wastewater contributes significantly to environmental pollution, while non-renewable phosphate rock reserves are rapidly depleting. Addressing these issues requires the development of advanced recovery technologies capable of reducing eutrophication and promoting circular phosphorus utilization. Electrochemical struvite crystallization offers a viable strategy, particularly when integrated with economical carbon felt cathodes, to replace traditional, more expensive materials. However, P recovery is often significantly compromised by the presence of complex co-existing substances in swine wastewater. This challenge motivated the current investigation of their specific effects on a carbon felt cathode-based struvite crystallization system. Single-factor experiments revealed that co-existing substances significantly inhibited phosphate recovery. Among the co-existing inorganic cations, Ca²⁺ and Fe³⁺ exhibited significantly stronger inhibitory effects on phosphate recovery compared to that of Na⁺. For the co-existing organics, sodium propionate, glutamic acid, and sodium humate exhibited significantly stronger inhibitory effects on phosphate recovery compared with starch and tetracycline. For swine wastewater, the phosphate recovery rate was 78.39%, and the recovered substance was struvite. The insights gained are crucial for optimizing the design and operation of robust and highly efficient electrochemical P recovery systems for practical swine wastewater treatment.