Study on the Resource Utilization and Purification Effect of Soilless Cultivation of Oenanthe javanica with Pig Farming Biogas Slurry

In order to study the resource utilization of nutrients and water purification effect under the pig farming-biogas slurry-vegetable model, a soilless cultivation depletion experiment was conducted, with three treatments of control, open field, and greenhouse cultivation of Oenanthe javanica. The growth status of Oenanthe javanica was studied, and the dynamic changes of eutrophication indicators and effluent water quality, as well as nutrient fate and supply-demand balance, were tested. The results show that the biomass of Oenanthe javanica treated in open field and greenhouse experiments was as high as 198.40 and 220.80 t·hm^-2, with a significant difference between them. On the 90th day, the removal rates of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD_Cr) all exceeded 93%, and the effluent quality met the "Irrigation Water Quality Standards for Farmland". Both treatments showed significant differences compared to the control. 76.28% and 77.30% of the TN removed in open field and greenhouse cultivation experiments were absorbed by Oenanthe javanica, respectively, while 23.72% and 22.70% were removed by microorganisms, respectively; 86.82% and 90.60% of TP removed were absorbed by Oenanthe javanica, while 13.18% and 9.40% were removed by microorganisms. COD_Cr was removed through microbial or oxidative degradation, with CO₂ accounting for 99.65% of the total gas released and CH₄ only accounting for 0.35%. Planting Oenanthe javanica can realize the resource utilization of pig biogas slurry and water quality purification. The quality and safety of Oenanthe javanica from the project complies with the requirements of GB 2762-2022 "National Food Safety Standard-Maximum Levels of Contaminants in Foods".