Search Results (2)

The aim of this 2-year study was to evaluate the influence of bed depth (40 and 60 cm) on the development of tropical ornamental species (Alpinia purpurata, Heliconia latispatha and Strelitzia reginae) and on the removal of different contaminants such as chemical oxygen demand (COD), nitrate (N-NO₃), ammonium (N-NH₄), total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), total coliforms (TCs) and fecal coliforms (FCs), in horizontal subsurface flow constructed wetlands (HSSF-CWs) for municipal wastewater treatment. The results showed that the depth of 60 cm favored the removal of COD, with removal efficiencies of 94% for the three plant species. The depth of 40 cm was most effective for the removal of N-NH₄ (80–90%). Regarding the removal of TN, the removals were similar for the different plants and depths (72–86%). The systems only achieved up to 60% removal of TCs and FCs. The depth of the CWs substrate and its saturation level influenced the development of ornamental vegetation, particularly flower production. For Heliconia latispatha, a bed depth level of 60 cm was more suitable, while for Alpinia purpurata 40 cm was better, and for Strelitzia reginae in both cases there was no flower production. The impact of bed depth on contaminant removal depends on the specific type of contaminant. Full article

Partially saturated vertical constructed wetlands (PSV-CWs) and free-flow vertical constructed wetlands (FFV-CWS) are treatment systems for which there is limited information on their operation in tropical climates and even scarcer information on their use for municipal/swine wastewater treatment. In this work, the removal of pollutants from municipal wastewater mixed with swine effluents was evaluated using PSV-CWs and FFV-CWs, at pilot scale, with the presence and absence of vegetation in a tropical climate. Six vertical flow CWs made up of polyvinyl chloride (1 m high and 0.5 m in diameter) were used; three were operated with free-flow conditions and three with partially saturated conditions. In each type of configuration, two reactors were planted with an individual of Heliconia latispatha, and one remained without vegetation. They were fed with municipal wastewater mixed with 50% of swine wastewater. Their ability to remove COD, TSS, TP, TN, N-NH₄, and N-NO₃ and plant development were evaluated. Heliconia latispatha registered better results of adaptation and vegetative development in the PSV-CWs in comparison with FFV-CWs measured as total biomass (5697.1 g/m² and 5095.7 g/m², respectively). PSV-CWs were slightly better for TSS elimination (4.21%), while FFV-CWs presented a better performance for TN removal (3.76%), N-NH₄ (3.94%) and N-NO₃ (4.76%) in the systems with vegetation; no significant difference (p ˃ 0.05) was found between the two types of CWs for the removal of COD and TP. However, significant differences (p ˂ 0.05) were found between the systems with vegetation and those without vegetation in both configurations. These results demonstrate that PSV-CWs represent a better option for the treatment of municipal/swine wastewater since their efficiency was slightly higher than, or similar to that of, FFV-CWs and allowed a better development of H. latispatha. Full article