Organics and nutrient removal from swine wastewater by constructed wetlands using ceramsite and magnetite as substrates

The discharge of swine wastewater has posted a serious threat to water bodies in rural areas and been receiving increasing attention worldwide. This study investigated the treatment performances of synthetic wastewater and real swine wastewater in subsurface flow constructed wetland (SSFCW) with different substrates (gravel, ceramsite and magnetite). The results showed that all systems exhibited better removal performances and higher nitrous oxide (N2O) emissions for synthetic wastewater than real swine wastewater. Magnetite-based CW was efficient for organic matter removal with chemical oxygen demand (COD) removal for 53.0–91.5 %. Ceramsite-based CW was effective in removing nutrients with 11.0–63.2 % for total nitrogen (TN) removal and 93.2–95.5 % for total phosphorus (TP) removal. Five dissolved organic matters (DOM) (UVA humic-like, UVC humic-like, tyrosine-like and tryptophan-like substances) were identified in swine wastewater before and after the treatment of CWs. The relative proportion of humic substance in all CWs fluctuated slightly which might result in the decrease of organics removal and the restriction of heterotrophic denitrification in CWs with swine wastewater. While the tyrosine-like and the tryptophan-like showed an opposite variation.