Search Results (3)

Constructed wetlands (CWs) attempt to simulate the physicochemical and biological processes that occur within a natural wetland and have been employed in recent decades for wastewater treatment. This work aims to review the use of CWs for domestic wastewater treatment in undeveloped or developing areas, including the amount of literature produced, the type of constructed wetland, the vegetation, the substrate, and the social benefits that have been achieved, through a qualitative methodology where different articles are collected from the Scopus and Web of Science databases after a strict revision by means of the PRISMA method (Preferred Reporting Items of Systematic Reviews and Meta-Analyses) and CASP (Critical Appraisal Skills Program). A total of 49 articles were selected, and co-occurrence and density maps were obtained; following this, three main themes and the five keywords with the highest correlation were identified. The literature analyzed in this work exposes different types of CWs where not only the hybrid, vertical, and horizontal flow systems stand out, but also the floating and aerated wetlands, which present high removal efficiencies. Additionally, new substrate materials, such as olote, palm shells, and coconut peat, and the ornamental plants usually used, such as Phragmites australis and Thypha latifolia, are discussed; however, new studies with vegetation that has been little studied but has a high potential to be implemented in areas with silvicultural characteristics stand out: Duranta repens, Pennisetum pedicellatum, and Pistia stratiotes. In conclusion, there is an advancement in the research of these systems, new configurations, substrates, and vegetation to treat domestic wastewater; in addition, these studies present an opportunity to continue studying the installation of CWs at the household level; however, compared to the other areas of application mentioned above, its implementation requires a greater challenge, since it requires a compact design and easy handling. Full article

Small size construction and demolition waste (CDW) is rarely reused and consequently causes environmental problems. CDW can increase aeration porosity of soil due to the big surface area and water absorption. In order to investigate the feasibility and function of CDW as a component of container substrate, we mixed four small sizes CDW (<10 mm) of 0–3, 3–6, 6–8, and 0–10 mm with clay soil according to the mass ratios of 20%, 35%, and 50% to plant one-year old Duranta repens cuttings, clay soil (CS) and pure CDW (CW) as the controls. Cluster analysis and principal component analysis (PCA) were performed to screen the most suitable particle size and proportion of CDW for plant growth and physiological function. The substrate containing 50% 3–6 mm CDW (S6) had the higher aeration porosity, lower water loss, better water retention and permeability, and therefore higher PCA score. The total branch length of plants in the S6 was increased by 18% and 71%, leaf area by 116% and 444%, and net photosynthetic rate by 10% and 59% compared to CS and CW, respectively. The suitable CDW has potential to improve substrate properties and can effectively improve plant growth. Meanwhile, the reuse of CDW can partially alleviate the problem of construction waste disposal and environmental pollution, and provide reference for the research on the combination of CDW and landscaping. Full article

From the leaves of Duranta repens (Verbenaceae) two new triterpene saponins, named durantanin IV (1) and V (2)were isolated.In addition, ten known compounds were isolated, namely a bidesmosidic saponin, oleanolic acid, three phenylethanoids and five flavonoids. All metabolites were isolated for the first time from this genus except for 3 (oleanolic acid) and 7 (E/Z acteoside). The structures were determined mainly by spectroscopic methods (UV, IR, HRESI-MS, ¹H-, ¹³C-NMR, ¹H-¹H COSY, HSQC and HMBC). Cytotoxic screening of the chloroform, ethyl acetate and methanol extracts was carried out on brine shrimps. In addition, the investigated methanol extract and compounds 1, 2 and 7 showed significant cytotoxic activity against a HepG2 cell line. Full article