Treatment of Domestic Wastewater in Colombia Using Constructed Wetlands with Canna Hybrids and Oil Palm Fruit Endocarp

Untreated domestic wastewater from rural areas poses significant risks to ecosystems and human health. Constructed wetlands (CWs) are a viable alternative for this wastewater treatment, enhancing nitrogen removal using substrates as carbon sources. This process is particularly beneficial for wastewater with low carbon-to-nitrogen (C/N) ratios, making the treated water suitable for agricultural irrigation. In this study, a Horizontal Subsurface Flow CW (HSF-CW) was evaluated using Canna hybrids and a mixed substrate of gravel and endocarp from oil palm fruit (EOP) as a carbon source to leverage its abundance in the region. It was also determined that the effluent complies with the permissible limits set by Resolution 1207 of 2014 from the Colombian Ministry of Environment and Sustainable Development, which establishes environmental standards for wastewater treatment to ensure environmental protection and enable safe reuse in agricultural irrigation. The key parameters analyzed included organic contaminants, heavy metals, nutrients, and microbiological indicators. Removal efficiencies of up to 91%, 94%, 98%, 52%, 73%, 78%, and 75% were achieved for BOD, TSS, total phosphorus, nitrates, nitrites, ammonium, and total nitrogen, respectively, demonstrating the CW's strong performance in contaminant removal and meeting most standards for agricultural irrigation. Although the carbon source was not highly efficient, the overall system performance supports its viability for improving water quality and promoting sustainable agricultural practices in rural areas.