Floating aquatic plants for total nitrogen and phosphorus removal from treated swine wastewater and their biomass characteristics

Abstract

In this study, the removal of nitrogen and phosphorus from the effluent of treated swine wastewater by Eichhornia crassipes, Pistia stratiotes, Limnobium laevigatum, and Lemna sp. was investigated. This study also aimed to quantify the potential biomass production and lignocellulosic composition of the floating plants cultured in the effluent. Plants were grown in treated swine wastewater effluent or Hoagland's solution. Pistia stratiotes showed the highest total nitrogen removal of 63.15% from the treated effluent. Lemna sp. showed the highest phosphorus removal of 36.15% from the treated effluent. However, Lemna sp. could not be further utilized because the plants could only be cultured for 13 days. The effluent likely had properties that inhibited the growth and nutrient uptake by the plants; further studies would be required to verify these properties. Pistia stratiotes and Eichhornia crassipes have higher tolerance than Lemna sp. to grow in treated swine wastewater. Eichhornia crassipes produced the highest biomass of 5.19 g dry weight/m²/day. Cellulose and lignin contents were higher in the Hoagland's solution treatment when compared with the effluent. However, based on an independent T-test analysis, the cellulose contents of plants grown in different media were not significantly different. Hemicellulose content was significantly different for Pistia stratiotes (p < 0.05). Finally, lignin content was significantly different for Eichhornia crassipes and Lemna sp (p < 0.05). The nutrient composition and available plant nutrients as well as other substances present in the effluent might have influenced the plant cell wall composition.

Keywords: Biomass; Floating aquatic plants; Nitrogen; Phosphorus; Treated wastewater.