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

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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 (NO3−), phosphate (PO4−3), hydrogen sulfide (H2S), biochemical oxygen demand (BOD), and potassium (K+). The significant pollutants reductions achieved NO3− by 73.9%, PO4−3 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. In response to the growing concerns of climate change and its impact on global food security, aquaculture has increasingly become an essential component in meeting the rising demand for aquatic food products. However, the sector faces notable environmental drawbacks, especially due to pollutant-rich wastewater, which threatens surrounding aquatic ecosystems. Constructed wetlands (CWs) have gained prominence as a sustainable and efficient approach for treating such wastewater by harnessing natural biological, physical, and chemical processes to reduce pollution while offering system resilience. This research evaluates a laboratory-scale vertical flow constructed wetland (VFCW) system with a volume of 360 L, configured for vertical flow operation, to treat aquaculture effluents. Experiments were conducted with hydraulic retention times (HRTs) of 3, 6, 9, 12, and 15 days, maintaining a steady hydraulic loading rate of 8.2 L/d/m2. The findings demonstrate the VFCW’s capacity to effectively lower NO3−, organic matter, and phosphorus concentrations, bringing these key water quality parameters within acceptable limits. Specifically, their concentration showed substantial decreases following treatment. Dissolved carbon dioxide (DCO2) levels decreased by approximately 71.4%. Biochemical oxygen demand (BOD) demonstrated a marked reduction of 88%. Potassium (K+) concentrations were lowered by 59%. Nitrate (NO3−) levels experienced a significant decrease of 74%, while nitrite (NO2−) concentrations were reduced by 93%. Phosphate (PO4−3) removal was highly effective, with a reduction of 96.3%. Finally, hydrogen sulfide (H2S) concentrations showed a substantial decline of 91.7%. These findings on treatment efficacy across key water quality parameters provide compelling evidence underscoring the critical need to advance more efficient and sustainable aquaculture practices. Moreover, they also serve as an essential foundation to optimize future field-scale applications focused on reducing environmental impacts. This laboratory-scale evaluation provides controlled insight into treatment efficiency; however, long-term seasonal validation and field-scale replication are recommended for full-scale implementation. Development and evaluation of VFCW system specifically designed for treating aquaculture wastewater at laboratory scale.Achievement of high pollutants removal efficiencies, including a (96.3%) reduction in PO4−3, and (74%) reduction in NO3− concentrations.Significant decrease in BOD by (88%), meeting and exceeding typical discharge standards.Demonstration of substantial reduction in DCO2 by (71.4%), K+ (59%), NO2− (93%), and H2S (91.7%), indicating broad-spectrum treatment effectiveness.Validation of lab-scale results is essential for optimizing full-scale nature-based wastewater treatment systems in sustainable aquaculture. Development and evaluation of VFCW system specifically designed for treating aquaculture wastewater at laboratory scale. Achievement of high pollutants removal efficiencies, including a (96.3%) reduction in PO4−3, and (74%) reduction in NO3− concentrations. Significant decrease in BOD by (88%), meeting and exceeding typical discharge standards. Demonstration of substantial reduction in DCO2 by (71.4%), K+ (59%), NO2− (93%), and H2S (91.7%), indicating broad-spectrum treatment effectiveness. Validation of lab-scale results is essential for optimizing full-scale nature-based wastewater treatment systems in sustainable aquaculture.

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