Search

The occurrence of ten target pharmaceuticals was investigated in drinking water sources and tap water in a city in the middle reaches of the Yangtze River, including erythromycin (ERY), roxithromycin (RTM), ciprofloxacin (CPX), ofloxacin (OFX), sulfadiazine (SDZ), sulfamethoxazole (SMX), oxytetracycline (OTC), tetracycline (TC), ibuprofen (IBF), and naproxen (NPX). And the corresponding ecological risk for three classes of aquatic organisms and human health risk for different life stages were estimated. Results demonstrated that nine pharmaceuticals except for TC were detected with the frequencies of 20-100% and the concentrations of

The process of urbanization aggravates the endogenous pollution of urban lake sediment, and polluted sediment may seriously affect the quality of the water in lakes. At present, it is difficult to distinguish the difference between sediment that is heavily polluted by nitrogen (N) and phosphorus (P) when using an analysis based on a physicochemical index classification. The current study applied phospholipid fatty acid (PLFA) technology to further analyze the sediment characteristics from the perspective of microbiology. Surface sediment from five urban lakes that are heavily polluted with N and P in Wuhan were sampled. Statistical approaches were used to analyze the microbial community structure in the sampled sediment, and to determine the correlations between the microorganisms and physicochemical indices. The most severely polluted lake sediment had similar PLFA structures, the highest saturated fatty-acid content, and bacteria as the dominant microorganism. However, there were differences between the microbial biomass of the various sediment samples, which may have been related to the degree of N and P pollution. Analysis of the microbial diversity in the sediment samples indicated that the bacteria were experiencing starvation and nutrient pressure, which may have been due to the dissolved oxygen concentration of the heavily polluted lake sediment. A correlation analysis showed that the endogenous N and P had different effects on the microbes of the polluted sediment. A redundancy analysis (RDA) demonstrated that the N/P ratio had the greatest influence on the PLFA species, accounting for 83% of the cumulative interpretation. To effectively promote the role of sediment microorganisms on circulating elements, it is necessary to regulate the N/P ratio of the sediment to some extent. When the N/P ratio in sediment exceeds 6, N pollution should be prioritized.

We investigated the long-term effects (6 years) of sediment improvement and submerged plant restoration of a subtropical shallow urban lake, Hangzhou West Lake China. To reveal the lake ecosystems variations, we analyzed the sediment properties, submerged macrophyte characteristics, sediment microorganisms, and benthic macroinvertebrate communities from 2015 to 2020. The ecological restoration project decreased sediment TP and OM, increased submerged macrophyte biomass and sediment microbial diversity, and improved the benthic macroinvertebrate communities in the restored area. The sediment TP decreased from 2.94 mg/g in 2015 to 1.33 mg/g in 2020. The sediment OM of the restored area decreased from 27.44 % in 2015 to 8.08 % in 2020. Principal component analysis (PCA) confirmed that the restoration improved the sediment conditions, making it suitable for the growth of submerged macrophytes, and then sped up the restoration and reconstruction of the lake ecosystem. These results have significant implications on the ecological management of shallow lakes.

The restoration of submerged macrophytes is an important step in lake ecosystem restoration, during which artificially assisted measures have been widely used for macrophyte recolonization. Compared with natural restoration, the impact of artificially assisted methods on methane (CH

The restoration of submerged macrophytes is commonly limited by abiotic stress. Here, we isolated PGPR strains from the rhizosphere of submerged macrophytes using ACC deaminase selective medium, and evaluated their growth promoting effects on Vallisneria natans (V. natans) under low light intensity and (or) high sediment organic matter load, and also explored the indigenous microbiome response of V. natans seedlings to PGPR inoculants. Ten isolates were chosen from the 252 isolated strains based on the ACC deaminase activity and the production of IAA and siderophore. M1 (Pseudomonas vancouverensis) and E15 (Enterobacter ludwigii) had the best growth promoting effects under low light stress and under double stress of low light and high sediment organic matter load, and the shoot height increased by 36% and 46%, respectively. The results of indigenous microbiome analysis showed that PGPR inoculants could regulate the relative abundance of unclassified_f_Enterobacteriaceae and improve the α-diversity of the rhizosphere bacterial community. Under high sediment organic matter load, inoculation of PGPR obviously shifted the β-diversity of rhizosphere bacterial communities to promote the early growth of V. natans. This study expands the application of plant–microbe interaction in the field of freshwater ecological restoration.

The outbreak of COVID-19 has led to the large-scale usage of chlorinated disinfectants in cities. Disinfectants and disinfection by-products (DBPs) enter rivers through urban drainage and surface runoff. We investigated the variations in residual chlorine, DBPs, and different aquatic organisms in the Hanjiang, Fuhe, and Qinglinghe Rivers in Wuhan during the COVID-19 pandemic. The sampling sites were from the wastewater treatment plant outlets to the downstream drinking water treatment plant intakes. Total residual chlorine and DBPs (dichloromethane and trichloromethane) detected in the river water ranged from 0 to 0.84 mg/L and 0 to 0.034 mg/L, respectively. The residual chlorine and DBPs showed a gradual reduction pattern related to water flow, and the concentration at intakes did not exceed the Chinese drinking water source quality standards. Phytoplankton and zooplankton densities were not significantly correlated with residual chlorine and DBPs. The fluctuations in phytoplankton resource use efficiency (RUE) and zooplankton RUE in the Fuhe River, with the highest residual chlorine, and the Qinglinghe River with the highest DBPs, were higher than those in the Hanjiang River. For benthic macroinvertebrates, the number of functional feeding groups in the Hanjiang River was higher than that in the Fuhe and Qinglinghe Rivers. The water and sediment bacterial communities in the Hanjiang River differed significantly from those in the Fuhe and Qingling Rivers. The denitrification function involved in N metabolism was stronger in the Fuhe and Qinglinghe Rivers. Structural equation modelling revealed that residual chlorine and DBPs impacted the diversity of benthos through direct and indirect effects on plankton. Although large-scale chlorine-containing disinfectants use occurred during the investigation, it did not harm the density of the detected aquatic organisms in water sources. With the regular use of chlorinated disinfectants for indoor and outdoor environments in response to the SARS-CoV-2 globally, it is still necessary to study the long-term and accumulated responses of water ecosystems exposed to chlorine-containing disinfectants., Graphical abstract Unlabelled Image

A novel composite photocatalyst with hydrophobicity, modified Sr/TiO2-PCFM (porous ceramic filter media), was synthesized and characterized by applying X-ray fluorescence (XRF), scanning electron microscope and energy dispersive spectroscopy (SEM/EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, Fourier transform infrared (FTIR) spectroscopy and UV–visible diffuse reflectance spectroscopy (UV–vis DRS). The results showed that the composite photocatalyst possessed a pure and highly crystalline anatase TiO2 layer and large specific surface area. The photodegradation of acephate by Sr/TiO2-PCFM was investigated under various conditions, e.g., the adsorption time, initial acephate concentration, Sr/TiO2-PCFM dosage, and pH. The acephate-preferred photocatalytic performance of the modified Sr/TiO2-PCFM with hydrophobic characteristics was explored for the first time in this study. The results revealed that the photocatalytic degradation process for the modified Sr/TiO2-PCFM preferred acephate over methylene blue (MB) in the acephate/MB mixture under ultraviolet light irradiation. The underlying mechanisms of the preferential degradation process of modified Sr/TiO2-PCFM was also studied. The results indicate that the modified Sr/TiO2-PCFM is a promising candidate for the preferential degradation of refractory organic matter in organophosphorus pesticides contaminated wastewater.

This research is the first report on the purification of domestic wastewater in respect to the application of strontium-doped TiO2 coated on porous ceramic filter media (Sr-TiO2/PCFM) in eight laboratory-scale vertical flow constructed wetlands under irradiation of UV light. All the major pollutant parameters of wastewater were investigated. The online parameters showed that the decrease of dissolved oxygen (DO) reached 68.89% and in the constructed wetlands group which had the Sr-TiO2/PCFM material and had a certain anti-clogging ability. By the presence of photocatalyst Sr-TiO2/PCFM material, the removal efficiency of COD reached over 80% and eventually stabilized at a higher level (over 71%). Besides that, the Sr-TiO2/PCFM material in constructed wetlands improved the average removal efficiency of total phosphorus (TP), total nitrogen (TN), NH4+-N, total suspended solids (TSS), and turbidity by 60.89%, 34.89%, 41.87%, 21.10%, and 36.85%, respectively. With Sr-TiO2/PCFM material, under the irradiation of UV light, the overall removal efficiency of organic matter removal in terms of dissolved organic carbon (DOC) was 52% in 4 h, which was the best compared with other constructed wetland groups. The results of this study may in turn support improved testing and better optimization of constructed wetland systems for wastewater treatment.

The pond-ditch circulation system (PDCS) is a promising solution for the restoration of rural wastewater. However, the underlying nitrogen removal mechanisms and roles of functional genes in nitrogen transformation processes have not yet been quantified at the molecular level. In this study, PDCSs have been found to have high removal efficiencies when the chemical oxygen demand (COD) and total nitrogen (TN) was high (>70%; 62.7–93.9%, respectively). Meanwhile, the presence of simultaneous nitrification, anaerobic ammonium oxidation (anammox), and denitrification processes were the primary nitrogen removal mechanisms in the PDCSs. According to the stepwise regression analysis and path analysis, two key functional gene groups, nosZ/(nirS + nirK) and (nxrA/amoA), were driving these major processes for TN and ammonia nitrogen (NH4+-N), respectively. Moreover, the key functional gene group narG/nxrA was affecting processes related to nitrate-nitrogen (NO3−-N) and nitrite-nitrogen (NO2−-N) conversion. Furthermore, results from the 15N isotope pairing technique suggested that for PDCSs, anammox was mainly responsible for nitrogen removal due to its high contribution to total N2 production (50.3%) in the ditch; denitrification, on the other hand, was primarily attributed to nitrogen removal, rather than the anammox process, in two ponds (41.3–43.1%).

Layered combined bio-ceramic, zeolite, and anthracite were used as substrates in vertical-flow constructed wetlands (VFCWs) for enhancing contaminant removal from synthetic municipal wastewater. Plant growth and propagation and the removal of organic matter, nitrogen, and phosphorus as well as its spatiotemporal variation were evaluated systematically. The results demonstrated that three different substrates were adequate for the establishment of Canna indica L., especially for zeolite. All small-scale VFCW units were simultaneous efficient in removing CODCr (73.9-78.7%), NH4+-N (83.8-89.9%), TN (88.3-91.5%), SRP (93.8-98.6%), and TP (87.1-90.9%) with a little significant difference on treatment performance. Different pollution removal processes followed a different trend because of their different removal mechanisms driven by the synergy of substrate, plant, and microorganism. Purification space moved down due to the adsorption capacity consumption of upper layer substrate over time. It was concluded that VFCWs filled with layered combined bio-ceramic, zeolite, and anthracite had great potential for treating municipal wastewater.

The occurrence of ten target pharmaceuticals was investigated in drinking water sources and tap water in a city in the middle reaches of the Yangtze River, including erythromycin (ERY), roxithromycin (RTM), ciprofloxacin (CPX), ofloxacin (OFX), sulfadiazine (SDZ), sulfamethoxazole (SMX), oxytetracycline (OTC), tetracycline (TC), ibuprofen (IBF), and naproxen (NPX). And the corresponding ecological risk for three classes of aquatic organisms and human health risk for different life stages were estimated. Results demonstrated that nine pharmaceuticals except for TC were detected with the frequencies of 20-100% and the concentrations ofLOQ-118.60 ng/L in drinking water sources. Only SMX and IBF were detected quantitatively with the highest concentrations of 0.69 ng/L and 1.28 ng/L in tap water, respectively. The concentrations of the target pharmaceuticals were lower than or comparable with those in other drinking water systems. The spatiotemporal variations of the target pharmaceuticals might be mainly attributed to their usage object, emission amount, and natural attenuation. The overall discrepancy of concentrations between drinking water sources and tap water might indicate the purification effect of drinking water treatment system. Individual pharmaceutical in drinking water resources posed negligible risks to invertebrate and fish; however, ERY, CPX, OFX, and SMX posed high risk to algae. Moreover, pharmaceutical exposure by tap water caused no risk to human health. Nevertheless, the long-term, chronic, and mixed risks of pharmaceuticals and the potential risk of antibiotic-resistant genes should be concerned. This study enriches environmental monitoring data of pharmaceuticals in drinking water sources and tap water, and provides scientific information for emerging pollutants management in drinking water system.

The diffusive gradients in thin films (DGT) technique was applied to determine the mechanism by which bentonite improves the eutrophic lake sediment microenvironment and enhances submerged plant growth. The migration dynamics of N, P, S, and other nutrient elements were established for each sediment layer and the remediation effects of bentonite and submerged plants on sediments were evaluated. Submerged plant growth in the bentonite group was superior to that of the Control. At harvest time, the growth of Vallisneria spiralis and Hydrilla verticillata was optimal on a substrate consisting of five parts eutrophic lake sediment to one part modified bentonite (MB5/1). Bentonite addition to the sediment was conducive to rhizosphere microorganism proliferation. Microbial abundance was highest under the MB5/1 treatment whilst microbial diversity was highest under the RB1/1 (equal parts raw bentonite and eutrophic lake sediment) treatment. Bentonite addition to the sediment may facilitate the transformation of nutrients to bioavailable states. The TP content of the bentonite treatment was 22.47%-46.70% lower than that of the Control. Nevertheless, the bentonite treatment had higher bioavailable phosphorus (BIP) content than the control. The results of this study provide theoretical and empirical references for the use of a combination of modified bentonite and submerged plants to remediate eutrophic lake sediment microenvironments.

Pond-ditch circulation system (PDCS) is a promising remediation strategy for rural wastewater treatment. Aquatic plants play nonnegligible roles in the nutrient removal of the PDCS. However, mechanisms of root exudates regulating nutrient removal in PDCSs remained unclear. In our study, the PDCS achieved higher total nitrogen (TN) and phosphorus (TP) removal rates (72.7–97.4%) compared to the static system. Protein contents in root exudates of the PDCS ranged from 0.041 to 1.332 mg L−1, showing negative associations with Simpson index. Lactic acid and tartaric acid in the PDCS varied from 0.045 to 0.380 mg L−1 and 0.024 to 5.446 mg L−1, which were tightly linked with TN, TP, and TP removal rates and most sediment properties, especially sediment total nitrogen (STN) and total organic carbon (TOC), and sediment inorganic phosphorus (SIP). Moreover, the top 3 relative dominant genus were Bacillus (0.11%–17.90%), Geobacter (0.35%–12.04%), and Clostridium sensu stricto 1 (0.14%–12.05%), which might be the predominant groups in nutrient removal of PDCSs. RDA results indicated that lactic acid, protein, and amino acids were positively correlated with Geobacter; while Bacillus was significantly affected by water content. Path analysis further demonstrated that the indirect effect of secretion from plant roots on nutrient removal rates was mainly through modulating bacteria diversity and relative abundance. Taken together, root exudates, especially protein, amino acids, and lactic acid, altered rhizosphere microbial relative abundance and diversity, where the impacts were bacterial species-dependent.

During decay, the sediment microenvironment and water quality are severely affected by excessive proliferation of harmful algae such as filamentous green algae (FGA). The frequency of this FGA is increased through global warming and water eutrophication. In the present study, the degradation processes of a common advantage FGA Cladophora oligoclora and its effect on nitrogen and phosphorus nutrient structure and bacterial community composition at the sediment-water interface were investigated by stable isotope labelling and high-throughput sequencing. The results showed that the decomposition process of C. oligoclona was fast, stable, and difficult to degrade. The changes in sediment δ15N values reached 66.68 ‰ on day 40, which indicated that some of the nitrogen had migrated to the sediment from C. oligoclona litter. TN and NH4+-N in the overlying water rapidly increased between days 0-10, NH4+-N rose to 78.21% of TN on day 40, resulting in severe pollution of ammonia in the overlying water. The nitrogen forms and contents in the sediment are mainly derived from the increasing ammonia nitrogen release. The TP and IP in the overlying water increased to the highest concentrations of 6.68±0.64, 6.59±0.79 mg·L-1 during the decomposition process, respectively, resulting in the migration of phosphate to the sediments with increasing phosphorus content. The abundance of the main dominant bacterial communities, such as Acinetobacter (0.08%-62.48%) and Pseudomonas (0.13%-20.36%) in sediments and overlying water has changed significantly. The correlation analysis results suggested that the phosphorus was mainly related to the bacterial community in the overlying water, while the various forms of nitrogen demonstrated a high relevance with the bacterial community in the sediment. Our research results will be valuable in evaluating the potential ecological risk of FGA decomposition and provide scientific support for shallow lake management and submerged vegetation restoration.

Hydrophytes are plants that grow in or on water. Their overgrowth adversely affects the ecosystem because of crowding out other aquatic organisms and polluting the environment with plant residue. In principle, cellulolytic bacteria can be used to degrade hydrophyte biomass. We here isolated and characterized four cellulolytic bacterial strains from Lake Donghu sediments (Wuhan, China) that are rich in organic matter and plant residues. The isolates (WDHS-01 to 04) represent Bacillus, Micromonospora and Streptomyces genera. The bacteria exhibited pronounced endoglucanase activities (from 0.022 to 0.064 U mL–1). They did not extensively degrade the emerged plant Canna indica L. However, in an Hydrilla verticillata (submerged plant) degradation medium, strain WDHS-02 exhibited a high degradation rate (54.91%), endoglucanase activity of 0.35 U mL–1 and the conversion rate of cellulose to reducing sugars of 7.15%. Correlation analysis revealed that bacterial endoglucanase activity was significantly correlated with the degradation rate, and acid detergent lignin, ash and cellulose content of the residual H. verticillata powder. In conclusion, the identified bacteria efficiently decomposed submerged plants without the need for acid–base pretreatment. They expand the set of known cellulolytic bacteria and can be used for natural degradation of submerged plants.

The excessive proliferation of filamentous green algae (FGA) has been considered to be one of the important factors that result in poor growth or even a decline in submerged macrophytes. This study aims to investigate why FGA has stronger growth advantage than that of submerged macrophytes in the co-culture system. Assimilation of nitrogen and phosphorus nutrients, kinetics, and interspecific nutrient competition model were studied to determine the dynamic changes in nutrient assimilation between submerged macrophytes and FGA in a co-culture system with ion depletion technique. The results showed that differences were observed in the assimilation of nitrogen and phosphorus by Vallisneria natans, Ceratophyllum demersum, and Cladophora oligoclona. C. oligoclona was able to assimilate and accumulate much more nitrogen than V. natans and C. demersum, with the content of nitrogen of 5.75% (dry mass). The lower value of Michaelis-Menten constant K m (0.34 mg/L) of C. demersum indicated that C. demersum had a greater affinity for phosphate. The interspecific competition results confirmed that the coexistence of V. natans and C. oligoclona, and C. demersum and C. oligoclona were unstable. Moreover, C. demersum had a stronger competitive ability than V. natans, and it can be used as a pioneer species for the recovery of submerged vegetation in eutrophic lakes.

Microzooplankton plays an important role in controlling the standing crop of phytoplankton and primary production. However, research on microzooplankton grazing has mainly focused on the ocean and only rarely on eutrophic lakes. In this study we investigated plankton community structures, microzooplankton grazing rates (m), and phytoplankton growth rates (mu) in order to explore microzooplankton grazing in 2 eutrophic sub-lakes of West Lake, Hangzhou, China (Waihu and Xilihu). Results showed that Pseudanabaena sp. was dominant in Waihu without submerged macrophytes, and the larger phytoplankton (> 2 mu m) biomass was higher than the picophytoplankton (< 2 mu m) biomass. However, Xilihu with macrophytes growing was mainly composed of diatoms and green algae, and there was no significant difference between larger phytoplankton and picophytoplankton biomass. Furthermore, in West Lake, the values of m (ranging from 1.58 similar to 3.33/d) and mu (ranged from 1.38 similar to 3.05/d) were higher than those in the ocean. The higher m, mu, and relative preference index (RPI) for picophytoplankton in Waihu indicated that microzooplankton had a significant size-selective grazing on picophytoplankton. However, no significant size-selection was found in Xilihu. These different responses of plankton in Waihu and Xilihu might explain why larger phytoplankton occupy a dominant position in eutrophic lakes.

Constructed wetlands (CWs) is an effective way to removal nitrogen (N) from swine wastewater, which accompanying with the process of ammonia (NH3) volatilization. However, the removal pathway of NH3 volatilization has adverse impacts on the natural biogeochemical cycle of N. Here, this paper presents the first attempt to investigate the potential use of clinoptilolite in reducing NH3 volatilization in integrated vertical-flow constructed wetlands (IVCWs) treating swine wastewater. The NH3 volatilization flux was measured via steady-state chambers. Results showed that the removal rate of TAN (total ammonia nitrogen, NH3 and NH4+-N) in clinoptilolite system was 96.1%, where 93.01% of that was removed by substrate adsorption, it was significantly higher (p

Biomanipulation of filter-feeding bivalves or fish can serve as complementary measures to zooplankton manipulation approach in lakes dominated by large-sized algae. A laboratory grazing experiment was conducted to compare the selective grazing of benthic bivalves (Hyriopsis cumingii) and planktivorous fish (silver carp) on particle size and algae species. Their combination grazing effects were also detected. The results showed that the clearance rates of silver carp were higher than that of H. cumingii, and that silver carp preferred particles in the 30–50 and 50–100 μm size fraction whereas H. cumingii did not show a significant selective grazing on seston size. Furthermore, the differences between the selective grazing of H. cumingii and silver carp on algae species were detected. Some algae species, which had not been digested well by silver carp, were not detected in H. cumingii’s pseudofeces. Similarly, some algal species in the pseudofeces of bivalves were not detected in the feces of fish. Moreover, the combined clearance rates of H. cumingii and silver carp (ranging from 12.14 to 95.99 mL g DW−1 h−1) were higher than that of single filter feeder (0.47 to 10.18 mL g DW−1 h−1). We suggest therefore that when using biomanipulation measures to control large-sized algal overgrowth, a combination of different filter feeders may be a better way considering their collaborative grazing in both particle size and algae species selectivity.

To find suitable wetland plants for constructed wetland-microbial fuel cells (CW-MFCs), four commonly used wetland plants, including Canna indica, Cyperus alternifolius L., Acorus calamus, and Arundo donax, were investigated for their electrogenic performance and physiological changes during non-growing seasons. The maximum power output of 12.82mW/m2 was achieved in the A. donax CW-MFC only when root exudates were being released. The results also showed that use of an additional carbon source could remarkably improve the performance of electricity generation in the C. indica and A. donax CW-MFCs at relatively low temperatures (2-15°C). However, A. calamus withered before the end of the experiment, whereas the other three plants survived the winter safely, although their relative growth rate values and the maximum quantum yield of PSII (Fv/Fm) significantly declined, and free proline and malondialdehyde significantly accumulated in their leaves. On the basis of correlation analysis, temperature had a greater effect on plant physiology than voltage. The results offer a valuable reference for plant selection for CW-MFCs.

Constructed wetland is an efficient way to lower N load from wastewater treatment plants. Here, the nitrogen removal rate and nitrogen balance, as well as the microbial community structure in IVCWs planted with different vegetation for treating reclaimed water were investigated. The results showed that IVCWs planted with vegetation generally achieved a higher TN removal rate than unplanted treatment, especially for Canna indica L. with 10.35% enhancement. Moreover, the microbial process proportion (83.87-87.94%) is the main N removal pathway in IVCW, and vegetation planting could increase 8.16% of it in average. The combination of quantitative polymerase chain reaction (qPCR) and high-throughput sequencing analysis revealed that IVCW planted with Canna indica L. showed the highest microbial abundant and biodiversity. The related denitrification genus Pseudomonas, Acinetobacter, Rhizobium, Bacillus and Rhodopseudomonas might be responsible for the high biological removal rate of nitrogen.

In a mesocosm experiment, the growth and photosynthetic responses of Vallisneria natans (Lour.) Hara was studied monthly in different water depths under flowing and static water. Water depth showed a significant effect on the shoot length, below-ground: above-ground biomass, and total biomass, while water velocity showed only a significant effect on the total biomass. In addition, total biomass and shoot length at 45, 75 and 105 cm was higher in the flowing treatment than that in the static treatment, which suggested that total biomass and shoot length are promoted by water flow to some extent. All of the investigated photosynthetic showed different changes with different months. Water depth exhibited significant effects on the maximum photosynthetic efficiency Fv/Fm, the maximum electron transport rate rETRmax, Chla, Chla + b and Chla/b, while water velocity showed only significant effects on Chla, Chla + b, ETRmax. The rapid light response curves varied differently with the time periods. In October, the time-course of slow chlorophyll a fluorescence induction curves, Fm peak, in the flowing treatment in 45, 75 and 105 cm is higher than that in the static treatment. All the results demonstrated that the differences between flowing and static water resulted in the different life strategy.

Phosphorous removal in adsorption had been extensively researched; however, the biological dephosphorization process and optimum operating parameters have not been discussed or quantified in Integrated Vertical-flow Constructed Wetlands (IVCWs). In this study, IVCWs planted with different plants were employed to evaluate total phosphorus (TP) treatment performance under different hydraulic retention times (HRTs), in summer and autumn. The results showed that the systems planted with Canna generalis showed the highest TP removal efficiency (77%) under a three-day HRT in autumn. The activities of exopolyphosphatase (PPX) and polyphosphate kinase (PPK) were determined, and it was found that PPK activity was seasonably variable and had been more active in autumn than that in summer (p

Modified bentonite granulars (MBGs) were prepared by acidification, natrification, calcination, and combined modification methods, and evaluated as effective in-situ adsorption materials to remove sediment phosphorus (P) in all fractions. The morphology and microstructure of MBG were characterized by scanning electron microscope (SEM), X-ray fluorescence (XRF), fourier transform infrared (FTIR) and X-ray diffraction (XRD). Results showed that the P removal capacity of CMBG-Na10-450 treated with 10% (g/g) Na2CO3 and calcined at 450 degrees C exhibited the highest P removal capacity. Under the optimal conditions of stirring tests, the removal rates of sediment TP, OP, IP, Fe/Al-P and Ca-P by CMBG-Na10-450 were 35.5%, 29.1%, 54.5%, 44.6% and 10.7%, respectively. The adsorption mechanism analysis found that MBG adsorbed sediment P mainly by anionic coordination exchange adsorption. These results indicated that modification enhanced the P adsorption capacity of bentonite, and the MBG can be further applied to control and reduce sediment P in eutrophication remediation. (C) 2017 Elsevier B.V. All rights reserved.