Effects of Four Species of Polygonum on Nitrogen and Phosphorus Removal from Simulated Domestic Sewage

Abstract

[Objective] To investigate the water purification capabilities of Polygonum species and assess their suitability for the remediation of domestic sewage. [Methods] Polygonum hydropiper, Polygonum orientale, Polygonum divaricatum and Polygonum lapathifolium were selected as the research objects. The removal effects of total nitrogen (TN), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), and total phosphorus (TP) in two concentrations of domestic sewage by these four species of Polygonum were discussed through a simulated hydroponic experiment. Additionally, the accumulation ability of Polygonum species to nitrogen and phosphorus in sewage was examined. [Results] (1) All four species of Polygonum exhibited good removal effects on nitrogen and phosphorus in two concentrations of domestic sewage. (2) Under high concentration sewage treatment, the removal rates of TN, NH4+-N and TP by Polygonum orientale, Polygonum divaricatum and Polygonum lapathifolium were 96.04%~97.41%, 94.60%~97.79% and 98.78%~99.68% (28 days), respectively, which were significantly higher than those of Polygonum hydropiper (p<0.05). (3) Under low concentration sewage treatment conditions, the shoot nitrogen and phosphorus accumulation of four species of Polygonum were 27.38~37.47 mg/plant and 7.65~10.11 mg/plant, respectively, with no significant difference between plants; Under high concentration sewage treatment, Polygonum orientale exhibits a strong nitrogen accumulation capability, with shoot nitrogen accumulation reaching 57.16 mg/plant, while Polygonum lapathifolium exhibits a strong phosphorus accumulation capability, with shoot phosphorus accumulation reaching 15.32 mg/plant. Conversely, Polygonum hydropiper displays weak nitrogen and phosphorus accumulation abilities. [Conclusion] These findings indicate that all four Polygonum species can be used to the remediation of low-concentration domestic sewage. Among them, Polygonum orientale, Polygonum divaricatum, and Polygonum lapathifolium are more suitable for treating high-concentration sewage. This study offers valuable insights into selecting plant materials for remediating domestic sewage.

Keywords

• domestic sewage
• polygonum plants
• nitrogen and phosphorus removal
• accumulation of nitrogen and phosphorus