Effects of Ornamental Plant Density and Mineral/Plastic Media on the Removal of Domestic Wastewater Pollutants by Home Wetlands Technology.

Wastewater treatment (WWT) is a priority around the world; conventional treatments are not widely used in rural areas owing to the high operating and maintenance costs. In Mexico, for instance, only 40% of wastewater is treated. One sustainable option for WWT is through the use of constructed wetlands (CWs) technology, which may remove pollutants using cells filled with porous material and vegetation that works as a natural filter. Knowing the optimal material and density of plants used per square meter in CWs would allow improving their WWT effect. In this study, the effect of material media (plastic/mineral) and plant density on the removal of organic/inorganic pollutants was evaluated. Low (three plants), medium (six plants) and high (nine plants) densities were compared in a surface area of 0.3 m2 of ornamental plants (Alpinia purpurata, Canna hybrids and Hedychium coronarium) used in polycultures at the mesocosm level of household wetlands, planted on the two different substrates. Regarding the removal of contaminants, no significant differences were found between substrates (p ≥ 0.05), indicating the use of plastic residues (reusable) is an economical option compared to typical mineral materials. However, differences (p = 0.001) in removal of pollutants were found between different plant densities. For both substrates, the high density planted CWs were able to remove COD in a range of 86-90%, PO4-P 22-33%, NH4-N in 84-90%, NO3-N 25-28% and NO2-N 38-42%. At medium density, removals of 79-81%, 26-32, 80-82%, 24-26%, and 39-41%, were observed, whereas in CWs with low density, the detected removals were 65-68%, 20-26%, 79-80%, 24-26% and 31-40%, respectively. These results revealed that higher COD and ammonia were removed at high plant density than at medium or low densities. Other pollutants were removed similarly in all plant densities (22-42%), indicating the necessity of hybrid CWs to increase the elimination of PO4-P, NO3-N and NO2-N. Moreover, high density favored 10 to 20% more the removal of pollutants than other plant densities. In addition, in cells with high density of plants and smaller planting distance, the development of new plant shoots was limited. Thus, it is suggested that the appropriate distance for this type of polyculture plants should be from 40 to 50 cm in expansion to real-scale systems in order to take advantage of the harvesting of species in these and allow species of greater foliage, favoring its growth and new shoots with the appropriate distance to compensate, in the short time, the removal of nutrients.

Renealmia L. f.: aspectos botânicos, ecológicos, farmacológicos e agronômico / Renealmia L. f.: botanical, pharmacological and agronomical aspects

RESUMO: Renealmia L.f. é um gênero de Zingiberaceae com inúmeros usos, entre eles: ornamental, medicinal e alimentício. Visando ressaltar a importância deste gênero como potencial fonte de recursos agroeconômicos apresenta-se esta revisão sobre aspectos botânicos, ecológicos, farmacológicos, e agronômicos. De um universo de 87 espécies formalmente inseridas em Renealmia, registrou-se indicação de uso popular para 18 destas. Em sua maior parte as indicações de uso estiveram associadas a R. alpinia, R. exaltata e R. guianensis englobando, principalmente, os usos ornamental, alimentício e medicinal. Dentre as 14 espécies com indicação de uso popular medicinal, registram-se pesquisas farmacológicas para apenas quatro: R. alpinia, R. exaltata, R. nicolaioides e R. thyrsoidea. Entretanto, estas pesquisas evidenciam um amplo espectro de bioatividade, com ênfase na ação anticancerígena e antiofídica, especialmente de R. alpinia. Apenas seis espécies foram avaliadas quanto a composição química (R. floribunda, R. guianensis, R. alpinia, R. chrysotricha, R. exaltata e R. nicolaioides), identificando-se perfil químico que corrobora a potencialidade anticancerígena e antiofídica para os representantes deste gênero. Evidenciou-se grande lacuna no que se refere ao conhecimento científico ou técnico para o cultivo de espécies de Renealmia. Isto pode se configurar num impedimento importante na utilização destas espécies como recurso econômico.

ABSTRACT: The Renealmia L.f. is a genus that belongs to the Zingiberaceae with several applications, including the ornamental, medicinal and food ones. Aiming to emphasize the importance of this genus as a potential agro-economic resource, a review of its botanical, pharmacological and agronomic aspects is presented. From 87 species formally inserted in the Renealmia, 20 were registered with popular uses. In general, these popular uses were associated with R. alpinia, R. exaltata and R. guianensis, mainly including the ornamental, nourishing and medicinal uses. Among 14 species with indication of popular medicinal use, pharmacological studies were registered for only four: R. alpinia, R. exaltata, R. nicolaioides and R. Thyrsoidea. However, these studies show a large bioactivity range, with emphasis in the anti-carcinogenic and antiophidic action, especially for R. alpinia. Only six species were analyzed in terms of chemical composition (R. floribunda, R. guianensis, R. alpinia, R. chrysotricha, R. exaltata and R. nicolaioides). Their chemical profiles corroborate the anti-carcinogenic potential for the representatives of this genus. There is a great scientific or technical gap on the cultivation of Renealmia species. This can be an important limiting factor in the use of these species as economical resource.