Adaptation and performance of Portulaca oleracea L. in a hybrid constructed wetland system for dairy wastewater treatment

Adaptação e desempenho de Portulaca oleracea L. em um sistema alagado construído híbrido para tratamento de efluentes de laticínios

ABSTRACT

The aim of this study was to evaluate the potential use of Portulaca oleracea L. in constructed wetlands (CWs) as part of a hybrid wastewater treatment system for small-scale dairy agroindustries. The experimental setup, located at the Federal University of Campina Grande, Brazil, consisted of a biodigester followed by a two-stage CW system. The first CW stage utilized Eichhornia crassipes M., while the second stage, the focus of this study, employed P. oleracea L. The research, conducted from 2018 to 2021, assessed the performance of P. oleracea in treating dairy wastewater. Water quality variables were monitored at four stages: raw wastewater, biodigester wastewater, and outputs from both CW stages. While the overall system demonstrated significant reductions in chemical oxygen demand (99.3%), biochemical oxygen demand (98%), and total Kjeldahl nitrogen (93.1%), the performance of P. oleracea was suboptimal. The species showed poor adaptation to the constantly flooded environment of the CW, exhibiting reduced growth and signs of physiological stress after 15 days. Despite these challenges, the second CW stage still contributed to pollutant removal, achieving a 40.9% reduction in total phosphorus compared to raw wastewater. This study highlights the importance of species selection in CW design and suggests that while P. oleracea may have potential in phytoremediation; its application in constantly flooded CW systems requires further investigation or modified management strategies.

Keywords:
species adaptation; phytoremediation; agroindustry