The production of both aboveground and belowground plant biomass in constructed wetlands (CW) is a poorly understood topic, although vegetation plays an important role in the process of pollutant removal from wastewater. The objective of this study was to evaluate the aboveground and belowground biomass production of Typha latifolia and Canna hybrids in a large-scale constructed wetland treating swine wastewater in tropical climates. Parameters, such as temperature, DO, pH, COD, TSS, TN, TP, and TC, as well as destructive and non-destructive biomass, were evaluated. It was found that, despite the high concentrations of pollutants, the vegetation adapted easily and also grew healthily despite being exposed to high concentrations of pollutants from swine water. Although Typha latifolia (426 plants) produced fewer plants than Canna hybrids (582 plants), the higher biomass of the Typha latifolia species was slightly higher than that of Canna hybrids by 5%. On the other hand, the proximity of the water inlet to the system decreased the capacity for the development of a greater number of seedlings. As for the elimination of pollutants, after treatment in the constructed wetland, COD: 83.6 ± 16.9%; TSS: 82.2 ± 17.7%; TN: 94.4 ± 15.8%; TP: 82.4 ± 23.2%; and TC: 94.4 ± 4.4% were significantly reduced. These results show that wetlands constructed as tertiary systems for the treatment of swine wastewater produce a large amount of plant biomass that significantly helps to reduce the concentrations of pollutants present in this type of water in tropical areas. The use of these plants is recommended in future wetland designs to treat swine wastewater.
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.
The use of environmentally friendly growth promoters and chemical agents in agricultural production is an important and favorable challenge, since it would reduce the use of agrochemicals and therefore less pollution for the field. The main objectives of this study were to make treatments on corn crops with auxins, gibberellins and hydrogen peroxide; as well as determining what the main positive or negative effects are. A factorial experiment design was carried out with five experiments which were: 1) auxins, 2) gibberellins, 3) Hydrogen peroxide (H2O2), 4) auxins-gibberellins and 5) control; the crop was corn, soil and plant samplings were made every 20 days, the variables analyzed in the plant were stem diameter, stem size, number of leaves and root size; the soil was analyzed for nitrites, nitrates, pH, EC and Eh; a statistical analysis was performed with these (ANOVA and Tukey's test). The five experiments were carried out and according to the results obtained, it can be said that the best treatments are those in which H2O2 and auxins were used, since these were in which the crop presented the highest values of the variables analyzed in the plant. These results suggest that in subsequent studies experiments using phytohormones and H2O2 together.
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