Effectiveness of constructed wetland as a green approach for aquaculture wastewater treatment: A case study

This study offers a detailed case-based evaluation of a laboratory-scale vertical flow constructed wetland (VFCW) system treating aquaculture wastewater characterized by a controlled effluent matrix and carefully managed hydraulic retention times (HRTs). Unlike more generalized constructed wetlands (CWs) applications, our research integrates specific operational parameters including vertical flow design, a 360 L treatment capacity, and a hydraulic loading rate of 8.2 L/d/m² to systematically assess the removal of critical pollutants such as nitrate (N<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math>), phosphate (P<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:math>), hydrogen sulfide (H₂S), biochemical oxygen demand (BOD), and potassium (K⁺). The significant pollutants reductions achieved N<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math> by 73.9%, P<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:math> by 96.3%, and BOD by over 90% demonstrate the system's high efficacy and validate its practical potential as a climate-resilient, nature-based treatment solution tailored for sustainable small-holder aquaculture systems. Indeed, our work emphasizes the quantification of multi-parameter attenuation under five distinct HRTs conditions during a short-term experimental trial, offering valuable, actionable insights for optimizing VFCW configurations adapted to aquaculture wastewater characteristics. This focused approach, addressing a specific aquaculture effluent matrix with operational conditions tailored to laboratory-scale treatment systems, clearly differentiates our contribution as an incremental yet valuable advancement. Moreover, it provides practical, real-world context insights and design implications for climate-resilient, nature-based wastewater treatment solutions that are well-suited to support sustainable aquaculture practices. We thereby explicitly acknowledge the foundation established by extensive prior research while delineating our study's unique contextual and operational contributions within the constructed wetland domain.