Search Results (6)

At present, studies on hydrophyte periphytic biofilm have mainly focused on natural water bodies or low-strength wastewater due to the inability of most plants to grow in high-strength wastewater. Therefore, the formation process and characteristics of plant periphytic biofilm growing in high-strength wastewater are still unclear. Based on the microcosm experiment, the formation process and characteristics of two kinds of plants (Myriophyllum elatinoides (Me) and Pontederia cordata (Pc)) periphytic biofilms were investigated with changes in water quality. The periphytic biofilm weight (BW) of Me and Pc reached equilibrium at 21 days, while the BW of Me was higher than that of Pc under high-load conditions (total nitrogen (TN) concentration ≥ 104.0 mg/L). When the TN concentration was 201.7 mg/L, the highest BW of Me was 0.99 mg/cm². In addition, the structural complexity of hydrophyte periphytic biofilm was higher under TN concentrations ≥ 70.9 mg/L than that under TN concentrations ≤ 56.9 mg/L. N concentration and environmental factors could affect periphytic BW and biofilm Chlorophyll a (Chla.). Through linear regression fitting, it was found that periphytic BW and biofilm Chla. were positively correlated with the concentrations of NH₄⁺-N and TN in water, while they were negatively correlated with the concentration of NO₃⁻-N. Random Forest results showed that NO₃⁻-N concentration had an important effect on hydrophyte periphytic BW. The results of this study provided a new understanding of the formation process and characteristics of aquatic plant periphytic biofilm under high-strength conditions and a prospect for sustainable development in the treatment of high-strength wastewater. Full article

This paper presents the role of soil nematodes as bio-indicators of the functioning of soil-plant beds in hydrophytic vertical-flow constructed wetland (VFCW) wastewater treatment plants. This study aimed to determine the abundance and trophic composition of nematode populations in seven soil-plant beds, the third component of plant-based wastewater treatment plants designed as Nature-Based Solutions (NBSs), in line with blue–green infrastructure and the closed-loop economy. The technology of this type of treatment plant is also in line with the idea of sustainability due to the very low energy requirements of the wastewater treatment system. In addition, soil nematodes were analysed in the soil adjacent to the WWTPs to assess the differences in trophic structure between these environments. The average nematode abundance in the soil-plant beds ranged from 606,000 [N·m⁻²] to 1,982,000 [N·m⁻²], with bacterivorous nematodes being the most abundant trophic group (61–73% of the population). This study’s results confirmed that soil-plant beds are abundantly populated by bacteria participating in key organic matter decomposition processes and nitrogen and phosphorus compound transformations, contributing to adequate wastewater treatment. The dominance of bacterivorous nematodes indicates a practical support of physicochemical and biological processes that reduce pollutant concentrations and eliminate pathogenic bacteria flowing into the deposits with the wastewater. Full article

Macrophytes have the potential to withstand pollutant-induced stress and can be used to clean contaminated water using phyto-extraction, phyto-degradation, phyto-filtration, phyto-stimulation, and phyto-volatilization technique(s). Phytoremediation through constructed wetlands (CWs) for eliminating inorganic and organic pollutants from household sewage and wastewater has attracted scientific attention. CWs are artificially engineered treatment systems that utilize natural cycles or processes involving soils, wetland vegetation, and plant and soil-associated microbial assemblages to remediate contaminated water and improve its quality. Herein, we present a detailed assessment of contaminant removal effectiveness in different CW systems, i.e., free-water surface or surface-flow constructed wetlands (FWSCWs/SFCWs), subsurface-flow constructed wetlands (SSFCWs), and hybrid constructed wetlands (HCWs). Several wetland floral species have been reported as potential phytoremediators, effectively reducing aquatic contamination through biodegrading, biotransforming, and bioaccumulating contaminants. Water hyacinth (Pontederia crassipes) is one of the most resistant macrophytes, capable of tolerating high nitrate (NO₃⁻) and phosphate (PO₄²⁻) concentrations. Other aquatic weeds also effectively alleviate biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), and pathogen levels and ameliorate the impact of different ionic forms of nitrogen (N), phosphorus (P), and trace elements (TEs). The review primarily focuses on using hydrophyte(s)-microbe(s) associations in different CWs as an essential phytoremediation tool for sustainable management of freshwater ecosystems, ecorestoration, and prospective resource recovery, favoring a circular bioeconomy (CBE). Full article

Constructed or treatment wetlands (CWs) are a sustainable option to clean wastewater in the face of water pollution problems. Consequently, this study was aimed at reviewing and analyzing the use of CWs in Mexico. This involved types, sizes, and functionality in the removal of pollutants, as well as the main plant species that are used. Furthermore, 67 studies regarding CWs were found, which were classified according to the treatment area as microcosms, mesocosms, pilot scale, and full-scale at 18, 30, 25, and 27%, respectively. The most used types of CWs are those of subsurface flow (87%) versus free-water surface (13%), of which horizontal flow direction (58%) are the most common. Considering Full-Scale CWs, the pollutant removal reported for COD, BOD₅, TN, and TP oscillated between 50–90%, 60–90%, 30–90%, and 30–70%, respectively. Among the vegetation that is more used for Mexican CWs, 78 different species were detected; Typha and Cyperus hydrophytes species and ornamental flowering plants as Zantedeschia aethiopica., Canna genus., Heliconia genus, Hedychium coronarium, and Anturium andreanum species (plants with commercial value) were the most used plants. It was concluded that although there is an important advance in the use of ecotechnology as it is an attractive answer for decentralized wastewater treatment in Mexico, results revealed the need to migrate towards the use of CWs in full-scale size, in order to address real pollution problems. Thus, the further implementation of CWs in rural and urban regions with similar tropical and subtropical characteristics as in Mexico is suggested by the authors. Full article

Phragmites australis (common reed) is one of the most extensively distributed species of emergent plant worldwide. The adaptive features of this plant show its competitive character. Owing to high intraspecific diversity of common reed, as well as its phenotypic plasticity, the plant shows a broad ecological amplitude. Moreover, the plant exhibits a high capacity for acclimatization to environmental conditions which are considered adverse. This plant has been used for many years in phytoremediation to purify various types of wastewater. Phragmites australis has a high ability to accumulate various nutrients, heavy metals, and micropollutants, and in this respect, it is superior to other aquatic plants. This review examines the existing literature on the biological and ecological properties of common reed, the use of common reed in wastewater treatment for removing pollutants and tolerance for metals, and in hydrophyte treatment systems. It seems vital to conduct further research on the physiology and biochemistry of the common reed, with the aim of increasing the plant’s efficiency for pollutants removal. Full article

In this research, we explore for the first time the use of leaf stomatal conductance (g_s) for phytotoxicity assessment. Plants respond to stress by regulating transpiration. Transpiration can be correlated with stomatal conductance when the water vapor pressure gradient for transpiration is constant. Thus, our working hypothesis was that the g_s measurement could be a useful indicator of the effect of toxic compounds on plants. This lab-scale study aimed to test the measurement of g_s as a phytotoxicity indicator. Our model plants were two common hydrophytes used in zero-effluent constructed wetlands for treating landfill leachate. The toxic influence of two types of leachate from old landfills (L1, L2) on common reed (Phragmites australis (Cav.) Trin. ex Steud.) and sweet flag (Acorus calamus L.) was tested. The g_s measurements correlated well with plant response to treatments with six solutions (0 to 100%) of landfill leachate. Sweet flag showed higher tolerance to leachate solutions compared to common reed. The estimated lowest effective concentration (LOEC) causing the toxic effect values for these leachates were 3.94% of L1 and 5.76% of L2 in the case of reed, and 8.51% of L1 and 10.44% of L2 in the case of sweet flag. Leachate L1 was more toxic than L2. The leaf stomatal conductance measurement can be conducted in vivo and in the field. The proposed approach provides a useful parameter for indicating plant responses to the presence of toxic factors in the environment. Full article