Bioremediation of slaughterhouse wastewater: Evaluation of nitrogen pollutant removal using constructed wetlands

The increasing generation of wastewater from slaughterhouses is seriously affecting ecosystems and human health due to high levels of contaminants such as TN, NH₄⁺, NO₃- and NO₂-, which, if not properly treated, can cause environmental problems such as eutrophication. Constructed wetlands (CWs) have emerged as an effective and economical alternative to conventional methods for wastewater treatment, including slaughterhouse wastewater. This study evaluated the efficiency of CWs in the removal of nitrogenous compounds in slaughterhouse wastewater using the plant species Typha latifolia and Heliconia latispatha. Eight horizontal subsurface flow constructed wetlands (HSF-CWs) units were implemented with different species combinations, and nitrogen pollutant concentrations were monitored over a one-year period. Results showed that the polyculture of T. latifolia and H. latispatha achieved the highest TN (64-65%) and NH₄⁺ (89%) removal efficiency, while systems with individual T. latifolia and H. latispatha showed intermediate efficiencies of 57% and 48%, respectively. For nitrate (NO₃-), the polyculture achieved an efficiency of 91%, while T. latifolia reached 78% and H. latispatha 68%. Finally, in nitrite removal (NO₂-), the polycultures showed a removal efficiency of 92%, while T. latifolia and H. latispatha achieved efficiencies of 82% and 73%, respectively. In comparison, the control presented the lowest efficiencies in all parameters (33-65%). This study concludes that HCs, planted with T. latifolia + H. latispatha, are a viable and economical alternative for the treatment of slaughterhouse wastewater, offering a more sustainable option compared to more complex and expensive technologies, such as electrocoagulation or nanofiltration systems. The use of polycultures and the combination of technologies is recommended to maximize treatment efficiency.