Constructed wetlands (CWs) are a promising alternative for conventional methods of wastewater treatment. However, the biggest challenge in wastewater treatment is the improvement of the technology used so that it is possible to remove micropollutants without additional costs. The impact of wastewater treatment in CWs on toxicity towards Aliivibrio fischeri, Daphnia magna and Lemna minor was investigated. The effects of feeding regime (wastewater fed in five batches per week at a batch volume of 1 L, or twice per week at a batch volume of 2.5 L) and the presence of pharmaceuticals (diclofenac and sulfamethoxazole), as well as the presence of Miscantus giganteus plants in CW columns (twelve of the 24 columns that were planted) were analyzed. A reduction in toxicity was observed in all experimental setups. The effluents from constructed wetlands were classified as moderately toxic (average TU for A. fischeri, D. magna and L. minor was 0.9, 2.5 and 5.5, respectively). The feeding regime of 5 days of feeding/2 days of resting resulted in a positive impact on the ecotoxicological and chemical parameters of wastewater (removal of TOC, N-NH4 and pharmaceuticals). Extended exposure of Miscantus giganteus to the wastewater containing pharmaceuticals resulted in elevated activity of antioxidant enzymes (catalase and superoxide dismutase) in leaf material.

• Keywords
• bioindication, constructed wetlands, ecotoxicity, environmental depollution, micropollutants, pharmaceutical pollution, removal of emerging contaminants,
• MeSH
• Antioxidants MeSH
• Water Purification * methods   MeSH
• Diclofenac toxicity   MeSH
• Catalase MeSH
• Wetlands MeSH
• Waste Disposal, Fluid methods   MeSH
• Wastewater * chemistry   MeSH
• Sulfamethoxazole toxicity   MeSH
• Superoxide Dismutase MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antioxidants MeSH
• Diclofenac MeSH
• Catalase MeSH
• Waste Water * MeSH
• Sulfamethoxazole MeSH
• Superoxide Dismutase MeSH

The objective of the present study was to develop a combined system composed of anaerobic biofilter (AF) and floating treatment wetlands (FTW) coupled with microbial fuel cells (MFC) in the buoyant support for treating wastewater from a university campus and generate bioelectricity. The raw wastewater was pumped to a 1450 L tank, operated in batch flow and filled with plastic conduits. The second treatment stage was composed of a 1000 L FTW box with a 200 L plastic drum inside (acting as settler in the entrance) and vegetated with mixed ornamental plants species floating in a polyurethane support fed once a week with 700 L of wastewater. In the plant roots, graphite rods were placed to act as cathodes, while on the bottom of the box 40 graphite sticks inside a plastic hose with a stainless-steel cable acting as the anode chamber. Open circuit voltages were daily measured for 6 weeks, and later as closed circuit with the connection of 1000 Ω resistors. Plant harvestings were conducted, in which biomass production and plant uptake from each of the species were measured. On average, system was efficient in reducing BOD5 (55.1%), COD (71.4%), turbidity (90.9%) and total coliforms (99.9%), but presented low efficiencies regarding total N (8.4%) and total P (11.4%). Concerning bioenergy generation, voltage peaks and maximum power density were observed on the feeding day, reaching 225 mV and 0.93 mW/m2, respectively, and in general decaying over the 7 days. In addition, plant species with larger root development presented higher voltage values than plants with the smaller root systems, possible because of oxygen release. Therefore, the combined system presented potential of treating wastewater and generating energy by integrating FTW and MFC, but further studies should investigate the FTW-MFC combination in order to improve its treatment performance and maximize energy generation.

• Keywords
• Bioelectricity, Constructed wetland, Ornamental plants, Phytoremediation, Renewable energy,
• MeSH
• Family Characteristics MeSH
• Electricity MeSH
• Electrodes MeSH
• Wetlands MeSH
• Wastewater MeSH
• Bioelectric Energy Sources * MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Waste Water MeSH

The benefits of plant-microbe interactions have been exploited extensively for nutrient removal. Radial oxygen loss in aquatic macrophytes potentially promotes nitrification and accelerates nitrogen removal through coupled nitrification-denitrification process. Nitrification is likely the limiting activity for an effective nitrogen removal in wetlands. In this work, we have quantified the effect of radial oxygen losses in Typha angustifolia plants in environments of contrasting salinities, including a temporary lagoon, a constructed wetland, and a river estuary. In all sites, radial oxygen diffusion occurred mainly at a narrow band, from 1 to 5 cm from the root tip, and were almost absent at the tip and basal sections of the root (> 5 cm). Root sections with active oxygen diffusion tended to show higher bacterial and archaeal densities in the rhizoplane according to 16S rRNA gene abundance data, except at higher salinities. Archaeal amoA /bacterial amoA gene ratios were highly variable among sites. Archaeal nitrifiers were only favoured over bacteria on the root surface of Typha collected from the constructed wetland. Collectively, radial oxygen loss had little effect on the nitrifying microbial community at the smaller scale (differences according to root-section), and observed differences were more likely related to prevailing physicochemical conditions of the studied environments or to long-term effects of the root microenvironment (root vs sediment comparisons).

• MeSH
• Ammonia metabolism   MeSH
• Plant Roots metabolism   MeSH
• Oxygen metabolism   MeSH
• Microbiota MeSH
• Nitrification physiology   MeSH
• Typhaceae metabolism   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Ammonia MeSH
• Oxygen MeSH
• RNA, Ribosomal, 16S MeSH

One of the possible ways to improve the operation efficiency of constructed wetlands and to prevent their clogging is the application of earthworms. They have already been successfully applied for vermicomposting and for sludge dewatering and treatment. A few studies have already examined the effect of earthworms on the treatment of wastewater by vertical flow constructed wetlands (VFCWs), but none of them have provided a yearlong research result from an open-air system or compared the effect that different seasons in a temperate climate area can have on these invertebrates. The goal of this research was to estimate the effect that earthworms and plants have on VFCW's operation. Four mesocosms (a filter, a filter with earthworms, a VFCW and a VFCW with earthworms) were built and their influent and effluent water quality was monitored for a period of 1 year. They were fed with wastewater coming from a building of the University of Bologna (Italy). The results have shown that the presence of earthworms in this specific system did not reduce the organic matter content of the substrate, but it has positively influenced plants' growth. However, since neither earthworms nor plants had a statistically significant effect on the effluent quality, it can be concluded that the integration of these invertebrates cannot improve wastewater treatment of vertical flow filters or constructed wetlands.

• Keywords
• Constructed wetlands, Earthworms, Filters, Plants, Seasonal effect, Wastewater treatment,
• MeSH
• Water Quality MeSH
• Wetlands MeSH
• Waste Disposal, Fluid methods   MeSH
• Wastewater chemistry   MeSH
• Sewage MeSH
• Oligochaeta physiology   MeSH
• Universities MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Italy MeSH
• Names of Substances
• Waste Water MeSH
• Sewage MeSH

Sludge treatment beds (STBs) have been used widely in many countries due to low energy consumption, low operating and maintenance costs, and better environmental compatibility. Penetration, evaporation, and transpiration are the main processes for sludge dewatering in STBs. However, the leachate quality from STBs usually cannot meet discharge limits. Moreover, such leachate has very low COD/N ratio, which makes it difficult to treat. In the present study, two subsurface flow (SSF) constructed wetlands (CWs) were investigated for the treatment of leachate from STBs under three different hydraulic retention time (HRT) (3 days, 4 days, 6 days), aiming for evaluating the effects of plants and HRT on treatment performance, as well as the potential of SSF CWs to treat sludge leachate with low COD/N ration. The results showed that plants play an important role in leachate treatment. The best treatment performance was achieved with HRT of 4 days. In this condition, the mean removal efficiencies of COD (chemical oxygen demand), NH4+-N, TN (total nitrogen), and TP (total phosphorus) in the planted and the unplanted CWs were 61.6% (unplanted - 3.7%), 76.6% (unplanted 43.5%), 70% (unplanted 41%), and 65.6% (unplanted 6%), respectively. Heavy metal concentrations were below the Chinese integrated wastewater discharge standard during the experimental period in the planted CW, and the removal efficiencies in the planted CW system were higher than in the unplanted CW system. In all, planted SSF CWs can be an effective approach in removing leachate from sludge treatment beds. Furthermore, considering to temperature and seasonal variation, the leachate from STBs needs to be further studied in pilot- and full-scale condition.

• Keywords
• Constructed wetland, Sludge leachate, Sludge treatment beds, Water purification,
• MeSH
• Water Purification MeSH
• Nitrogen analysis   MeSH
• Phosphorus analysis   MeSH
• Water Pollutants analysis   MeSH
• Biological Oxygen Demand Analysis MeSH
• Wetlands * MeSH
• Waste Disposal, Fluid methods   MeSH
• Wastewater MeSH
• Sewage MeSH
• Plants MeSH
• Metals, Heavy MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Nitrogen MeSH
• Phosphorus MeSH
• Water Pollutants MeSH
• Waste Water MeSH
• Sewage MeSH
• Metals, Heavy MeSH