Water Purification Capacity Research Articles

3D printing of porous ceramic scaffold based halloysite clay for efficient seawater desalination

Solar driven interfacial evaporation is an efficient and environmentally friendly method to achieve sustainable desalination and address the long-term freshwater shortage crisis. Here, a polydopamine (PDA) coated porous ceramic scaffold (PCS) based on halloysite clay nanotubes (HNTs) is developed as a solar interfacial evaporator for efficient seawater desalination. The PCS is prepared by direct ink writing (DIW) 3D printing technology, in which the ink is composed of HNTs (67 %), sodium silicate (0.2 %) and polyethylene glycol (3.7 %). The PCS has excellent compressive strength, corrosion resistance and chemical stability. PDA coating enhances the hydrophilicity of the scaffold, which can promote water replenishment on the evaporation surface and achieve effective anti-salt seawater desalination. The PDA coated PCS exhibits an excellent indoor water evaporation rate of 1.53 kg m-2h−1 and efficiency as high as 84.2 % under 1 sun irradiation, and the evaporator shows good stability in 10 cycles of solar evaporation experiments. Moreover, the PCS maintains a high evaporation rate of ∼ 2.4 kg m-2h−1 and good salt resistance in a long-term real seawater experiment for seven consecutive days. When this evaporation experiment was operated outdoors, high water purification capacity could be achieved. In total, PDA coated porous HNTs ceramic scaffolds show promising potential for application in the fields of solar thermal conversion and seawater desalination.

Evaluation of Coastal Ecological Security Barrier Functions Based on Ecosystem Services: A Case Study of Fujian Province, China

Constructing coastal ecological security barriers is beneficial for preventing environmental degradation and enhancing resilience to natural disasters. This study examines the functionality of these barriers from an ecosystem service perspective, developing an Ecosystem Security Barrier Function (ESBF) index to analyze its spatiotemporal variations. From 2000 to 2020, habitat quality in the study area experienced a slight decline, while water supply capacity initially increased and then decreased. Water purification capacity hit its lowest point in 2015 before improving. The ESBF generally ranged from moderate to high levels, with higher values in the northwest and lower values in the southeast, showing strong spatial autocorrelations. Despite mild degradation in some areas, overall stability was maintained with frequent transitions between ESBF levels. Utilizing the Multiscale Geographically Weighted Regression (MGWR) model, we conducted a grid-scale analysis of the driving mechanisms behind ESBF. We found that precipitation, elevation, and the Normalized Difference Vegetation Index (NDVI) positively correlated with ESBF, whereas population density, land use, and nighttime lights negatively correlated. The relationship between temperature and ESBF showed a “north-positive, south-negative” pattern. The study recommends enhancing coastal wetland restoration, strengthening protective forest construction, and effectively controlling pollutant sources entering the sea to safeguard and improve the ecological security barrier function.

Norfloxacin affects inorganic nitrogen compound transformation in tailwater containing Corbicula fluminea

The Asian clam, Corbicula fluminea, commonly used in engineered wetlands receiving tailwater, affects nitrogen compound transformation in water. This study investigates how a commonly observed antibiotic in tailwater, norfloxacin, impact nitrogen compound transformation in tailwater containing C. fluminea. The clam was exposed to artificial tailwater with norfloxacin (0, 0.2, 20, and 2000 μg/L) for 15 days. Water properties, C. fluminea ecotoxicity responses, microorganism composition and nitrification- or denitrification-related enzyme activities were measured. Results revealed norfloxacin-induced increases and reductions in tailwater NH4+ and NO2− concentrations, respectively, along with antioxidant system inhibition, organ histopathological damage and disruption of water filtering and digestion system. Microorganism composition, especially biodiversity indices, varied with medium (clam organs and exposure water) and norfloxacin concentrations. Norfloxacin reduced NO2− content by lowering the ratio between microbial nitrifying enzyme (decreased hydroxylamine oxidoreductase and nitrite oxidoreductase activity) and denitrifying enzyme (increased nitrate reductase and nitrite reductase activity) in tailwater. Elevated NH4+ content resulted from upregulated ammonification and inhibited nitrification of microorganisms in tailwater, as well as increased ammonia emission from C. fluminea due to organ damage and metabolic disruption of the digestion system. Overall, this study offers insights into using benthic organisms to treat tailwater with antibiotic residues, especially regarding nitrogen treatment.

Microbial succession and enrichment of antibiotic resistance genes during algal-bacterial biofilm purification of aquaculture wastewater

This study involved the establishment of algal-bacterial biofilms on the surface of carbon fiber-based artificial aquatic plants, utilizing algal-bacterial symbiosis for the purification of aquaculture wastewater. The algae-bacteria consortium exhibited strong photosynthetic activity, as indicated by the chlorophyll a + b content (0.918 ± 0.029 mg/g carbon fiber (CF)). Particularly, during the initial 7 days, algal-bacterial biofilm displayed robust water purification activity and capacity, with a significant reduction in total phosphorus (TP) of 39.44 % ± 2.43 % observed. The microbial community of the biofilm was diverse, primarily dominated by Proteobacteria, Cyanobacteria, Actinomycetota, and Planctomycetota. Among these, Proteobacteria were in the highest abundance ranging from 39.18 % to 40.61 %. Changes in Cyanobacteria, driven by nutrient level alterations, not only impacted species abundance but also posed a risk of promoting the spread of antibiotic resistance genes (ARGs). Through the complex interactions among biological communities, 15 types of ARGs have been enriched on the algal-bacterial biofilm, among which Multidrug, Bacitracin, Aminoglycoside, and Glycopeptid have a higher abundance. Contigs and network analysis indicate that Nannocystis, Sphingorhabdus, and Polynucleobacter are the key hosts and it is found that their abundance will increase during the purification of water quality by the algal-bacterial biofilm. This study highlighted the risk of ARG transmission in aquaculture effluent treatment with algal-bacterial biofilms.

Spatiotemporal Heterogeneous Responses of Ecosystem Services to Landscape Patterns in Urban–Suburban Areas

With the acceleration of urbanization, the ecosystem around cities is facing severe challenges. The drastic changes in the landscape pattern, especially in urban–suburban areas, are usually regarded as one of the main drivers. However, the spatiotemporal heterogeneous impacts of landscape patterns on the ecosystem services in this region remain unclear. To address this issue, we propose a novel framework integrating the InVEST-based ecosystem service assessment and spatiotemporal weighted regression (STWR)-based analysis of the spatiotemporal heterogeneity in urban–suburban areas, and apply it to the empirical study of Fuzhou City from 2000 to 2020. It first utilized the InVEST model to build a comprehensive ecosystem service index (CES) from five aspects (i.e., habitat quality, carbon storage, water yield, soil retention, and water purification capacity). Then, four landscape pattern indices (LPIs) (i.e., patch density (PD), area-weighted mean fractal dimension (FRAC_AM), splitting (SPLIT), and Shannon’s diversity (SHDI) index) were selected to build the STWR model. We compared and analyzed the differences in the spatial coefficient surfaces and significance tests generated by the STWR model in urban, urban–suburban, and rural areas. Results show that the following: (1) The CES in Fuzhou shows an upward trend from the urban area to the urban–suburban and rural areas, with significant gradient differences. (2) Compared with other areas, the LPIs in urban–suburban areas show more fragmentation, discreteness, and diversity, indicating more socioeconomic activities. (3) Although LPIs’ impacts on CES change over time (increasing from 2005 to 2010 and 2020 but decreasing in 2015), their effects are relatively low in urban–suburban areas, significantly lower than in urban areas. (4) Interestingly, the LPI coefficients near the urban–suburban boundary seem more significant. (5) This framework can effectively reveal the spatiotemporal heterogeneous relationships between various LPIs and CES, thus guiding concrete policies and measures that support decision-making for improving the ecosystem services surrounding cities through shaping landscape patterns.

The relationship between disaster resilience and household food security in a disaster-prone area in Kumamoto prefecture, Japan

This study explores the relationship between residents’ disaster resilience and potential household food security in the context of natural disasters. Disaster resilience capacity consists of absorptive capacity, adaptive capacity, and transformative capacity, while household food security is composed of food availability, accessibility, and utilization. Based on data from 539 questionnaires administered to residents in Kumamoto Prefecture, Japan, this study examines households’ disaster resilience capacity and food security conditions. The entropy method is adopted as a quantitative assessment approach to integrate the data, and a Tobit model is constructed to detect the correlation between households’ disaster resilience capacity and food security. We draw five main findings from the results. (1) Over half of the respondents do not have good food security; moreover, food accessibility is the poorest dimension, as reflected by low scores for water purification capacity and facility preparedness. (2) Most of the respondents do not have high disaster resilience capacity; their transformative capacity is the lowest, followed by absorptive and adaptive capacity. (3) There is a significant positive correlation between disaster resilience and household food security. (4) Disaster damage experience restrains residents’ food utilization. (5) The elderly and senior population may be exposed to food-borne diseases because of their low food utilization. This study provides insights into the influence of disaster resilience activities on household food security before a disaster hits. The study informs the debate on the association between disaster resilience and household food security so as to aid future disaster risk reduction management.

Greenhouse gases emissions and carbon budget estimation in horizontal subsurface flow constructed wetlands with different plant species

Constructed wetlands (CWs) are pivotal for wastewater treatment due to their high efficiency and numerous advantages. The impact of plant species and diversity on greenhouse gas (GHG) emissions from CWs requires a more comprehensive evaluation. Moreover, controversial perspectives persist about whether CWs function as carbon sinks or sources. In this study, horizontal subsurface flow (HSSF) CWs vegetated with Cyperus alternifolius, Typhae latifolia, Acorus calamus, and the mixture of these three species were constructed to evaluate pollutant removal efficiencies and GHG emissions, and estimate carbon budgets. Polyculture CWs can stably remove COD (86.79 %), NH4+-N (97.41 %), NO3−-N (98.55 %), and TP (98.48 %). They also mitigated global warming potential (GWP) by suppressing N2O emissions compared with monoculture CWs. The highest abundance of the Pseudogulbenkiania genus, crucial for denitrification, was observed in polyculture CWs, indicating that denitrification dominated in nitrogen removal. While the highest nosZ copy numbers were observed in CWs vegetated with Cyperus alternifolius, suggesting its facilitation of denitrification-related microbes. Selecting Cyperus alternifolius to increase species diversity is proposed for simultaneously maintaining the water purification capacity and reducing GHG emissions. Carbon budget estimations revealed that all four types of HSSF CWs were carbon sinks after six months of operation, with carbon accumulation capacity of 4.90 ± 1.50 (Cyperus alternifolius), 3.31 ± 2.01 (Typhae latifola), 1.78 ± 1.30 (Acorus calamus), and 2.12 ± 0.88 (polyculture) kg C/m2/yr. This study implies that under these operation conditions, CWs function as carbon sinks rather than sources, aligning with carbon peak and neutrality objectives and presenting significant potential for carbon reduction efforts.

Packing blockage and power generation of constructed wetland coupled microbial fuel cell systems using biochar as electrode and filler with different ratios

This article investigated the electrochemical performance, water purification capacity and packing clogging of constructed wetland-microbial fuel cells coupled reactors (CW-MFCs). The CW-MFCs-B (B = 100 % biochar filler) reactor performed the best under intermittent conditions, with a power density of up to 33.7 mW/m2. Regarding TOC removal, CW-MFCs-G (G = no biochar filler) was the least effective when the system was in continuous flow. The effect of the other two reactors with biochar filler addition (BG = 50 % and B = 100 %) was similar, indicating that the biochar functioned well as the CW filler to remove organic matter. Regarding NH4+-N removal, removal rates varied at different HRTs: HRT = 2 days > intermittent flow > HRT = 0.5 days. Among them, CW-MFCs-B was the most effective, with a maximum of 65.10 %. The clogging index Φb of the three reactors were 2.83 (B), 1.77 (BG), and 0.72 (G). The CW-MFCs-B reactor showed good effluent treatment and had the best electricity production but the most severe clogging. There may be a certain connection between H2O2 concentration and the degree of CW clogging. CW-MFC with biochar electrode and gravel filler may be suitable for long-term operation.

Experimental study on mine water purification mechanism for broken coal and rock masses in the underground reservoir of ecologically vulnerable mining area.

Water-rock interaction mechanism and water purification capacity of broken coal and rock masses are very important for the efficient operation of the underground reservoir. In this paper, a water purification simulation device for an underground mine reservoir was designed. The experimental study on the dynamic interaction between broken coal and rock masses and mine water was carried out. The water purification mechanism is analyzed from the changes in rock mineral composition and mine water quality before and after the test. The results show that after the broken coal and rock mass purification, the water turbidity and the concentration of chlorides and suspended solids decreased obviously. The water purification capacities of mudstone and sandstone are stronger than that of coal samples. After 60days of reaction between the working face sewage and the broken samples (mudstone, sandstone, and coal), the turbidity, chromaticity, and residual chlorine decreased by > 90%, 90%, and 60%, respectively; and COD decreased by 35.29%, 30.59%, and 28.99%, respectively. While the TDS and the total hardness increased by about 40%, 30%, and 10% for the mudstone, sandstone, and coal, respectively. It shows that coal also has the worst degradation performance. The water purification effect of broken coal and rock masses has a significant time effect. The early stage of water-rock interaction is dominated by mineral dissolution, and the middle stage is dominated by precipitation and adsorption. The pH value of the solution has a certain influence on the ion change. In the later stage, the water-rock interaction is weak in a dynamic equilibrium state, and the change in the mine water quality index is not obvious. Considering the influence of rock lithology on water quality and the law of water-rock interaction time, the construction site selection and water storage time optimization of underground reservoirs in Jinjie Coal Mine were carried out, respectively.

Assessment of water-related ecosystem services based on multi-scenario land use changes: focusing on the Poyang Lake Basin of southern China

A scientific understanding of the trends of water-related ecosystem services (WESs) under different scenarios is crucial to improving WESs and maintaining ecological security. However, there is a lack of high-resolution land use simulation and assessment of WESs under the SSP-RCP scenarios, and the impacts of different land-use change (LUC) on WESs are not clear. This study focused on the Poyang Lake Basin (PYLB), utilizing the SSP-RCP scenarios, the PLUS model and the InVEST model to explore the dynamic changes of land use and WESs historically and in the future, and to reveal the impacts of specific LUC on WESs from 2000 to 2020. The results demonstrated that: (1) The forest land increased under both SSP1-2.6 and SSP2-4.5 scenarios but increased first and then decreased under SSP5-8.5 scenarios; Cropland increased significantly under SSP5-8.5 scenarios, and the construction land showed an expansion trend under the three scenarios. (2) From 2000 to 2020, only the water purification capacity decreased, while the rest of the WESs increased. Under the SSP1-2.6 scenario, the overall benefits of the WESs in the PYLB were the highest. (3) Between 2000 and 2020, deforestation in the PYLB brought about the greatest increase in the water yield (+9.06 × 108 m3). The increase in the construction land brought about the most water conservation loss (−18.19 × 108 m3). Additionally, the forest expansion and cropland reduction brought about the largest increase in soil retention (+3.94 × 105 t and +4.79 × 105 t) and enhanced water purification, and the opposite was true for deforestation. The conclusions can provide an important basis for the ecological protection and high-quality development of the PYLB.

Environmental compatibility of pervious concrete with recycled coarse aggregate applying in riparian buffer area

Knowledge of the environmental compatibility of pervious concrete with recycled coarse aggregate (RA) is significant, especially when used in riparian buffer areas. In this study, investigations on the growth performance of two grass combinations (I: Festuca and Ryegrass; II: Cosmos bipinnata, Festuca and Ryegrass) and water purification capacity of the pervious concrete with the RA were carried out to evaluate the environmental compatibility; the former was performed by measuring the maximum height and germination rate during 28 days of growth; the latter was measured using a water immersion test with measurements of the nutrient content (NO3--N, NO2--N, NH4+-N, T-N, PO43--P, and T-P) and organic matter (COD and DOC) at certain intervals. Prior to that, the effects of RA grading (5–15 mm, 15–20 mm, 20–25 mm) and water-cement ratio (W/C) (0.4, 0.45, 0.5) on strength and porosity were determined, along with suitable concrete being selected for the test of environmental compatibility. The results showed that a maximum RA grading of 20–15 mm was the best for plant growth, manifesting the greatest maximum height of 9.8 cm and germination rate of 42.42%. Pervious concrete with vegetation can efficiently purify the surrounding water, with a removal efficiency of more than 98% for NH4+-N, T-P, PO43--P, and COD. The removal efficiency increased over time, except for the DOC. W/C had no distinct effect on plant growth and matter removal, except for NO2--N and NO3--N, which increased as W/C increased. This paper highlights the environmental technical merits of pervious concrete with RA and provides technical support for using the material in riparian buffers.

Diversity and Their Response to Environmental Factors of Prokaryotic Ultraplankton in Spring and Summer of Cihu Lake and Xiandao Lake in China

Ultraplankton plays an important role in the biogeochemical cycles of aquatic ecosystems. Based on 16S rRNA gene sequencing technology, the community structure composition of prokaryotic ultraplankton and its relationship with environmental factors were analyzed. The results showed that Cihu Lake was experiencing eutrophication and that Xiandao Lake was in the process of changing from mesotrophic to oligotrophic conditions. Cihu Lake and Xiandao Lake were regulated primarily by nitrogen nutrients. Proteobacteria, Bacteroidota, Cyanobacteria, and Actinobacteriota were the major phyla of prokaryotic ultraplankton in both lakes. Among them, Cyanobacteria dominate in the summer in Cihu Lake, which can have seasonal cyanobacterial blooms. Seasonal variation significantly affects the diversity and community structure of prokaryotic ultraplankton in the lakes, with temperature and dissolved oxygen being the key environmental factors determining plankton community composition. The PICRUSt functional prediction analysis indicated a higher water purification and exogenous pollution remediation capacity of the microbial communities of Xiandao Lake, as well as in the spring samples of Cihu Lake. In this study, the diversity and spatial–temporal succession patterns of prokaryotic ultraplankton in Cihu Lake and Xiandao Lake were elucidated, providing a useful reference for the lake environmental protection and water eutrophication management in Cihu Lake and Xiandao Lake.

Assessment of Water Yield and Water Purification Services in the Arid Zone of Northwest China: The Case of the Ebinur Lake Basin

Assessing how land-use changes will affect water-producing ecosystem services is particularly important for water resource management and ecosystem conservation. In this study, the InVEST model and geographical detector were used to assess the water ecosystem service functions of the Ebinur Lake Basin and analyze their relationship with land-use changes. The results show that in the past 25 years, the water yield of the study area showed a trend of a strong yield at first and then a weaker one; there was a relatively large water yield in the west and southeast regions of the basin. The order of water yield for different land-use types is as follows: forest land > grassland > water area > unused land > crop land > construction land. After 2010, the output load of nitrogen and phosphorus increased; thus, the water purification ability weakened. The main land-use types in areas that demonstrate a large change rate in water purification capacity in the basin are cultivated land and construction land. Changes in the two water ecosystem services were associated with land-use changes. Geodetector analysis results further validated this conclusion. This study proposes a viable, replicable framework for land-use decisions in ecologically fragile watersheds. This study not only helps to gain insight into urban growth patterns in the study area but also helps to inform different land-use stakeholders.

Study on Water Purification Efficiency and Influencing Factors of a Constructed Wetland in Jiaxing

Constructed wetland plays an important role in the removal of micro-polluted water pollutants in urban water sources. However, the water purification capacity and influencing factors of the constructed wetlands still need to be explored. This study monitored the turbidity, ammonia nitrogen (NH3-N), dissolved oxygen (DO), and chemical oxygen demand (COD) at the water inlet and outlet of Shijiuyang Wetland in Jiaxing City from 2019 to 2021. The results showed that the turbidity and the wetland turbidity removal rate stayed high. The DO couldn’t meet national standard III for surface water during the high temperature time in summer, and NH3-N and COD are stable within national standard III. The partial regression analysis shows that the addition of chemicals is the most important factor affecting the turbidity. Temperature had the most important affect to NH3-N and DO, the higher the temperature, the lower the NH3-N value and the DO. The flow rate is the most important factor affecting the COD, the higher the flow rate, the lower the COD. Moreover, this paper proposes operation and maintenance improvement measures for the problem of excessive turbidity and DO in Shijiuyang Wetland. The research results are conducive to improving the understanding of water security in the Yangtze River Delta region.

Water Purification Capacity of the Constructed Wetland to Micro-Pollution Water Source —— a Case Study in Jiaxing

Constructed wetlands are commonly applied to improve and maintain water quality of micro-polluted water sources as a feasible and cost-effective technique. However, the purification capacity of the constructed wetland for micro-polluted water was lacking of understanding. This study collected the turbidity, ammonia nitrogen (NH3-N), nitrite nitrogen (NO2-N), total nitrogen (TN), Fe, Mn, total phosphorus (TP), permanganate index (CODMn), dissolved oxygen (DO), and chemical oxygen demand (COD) at the water inlet and outlet of Guanjinggang Wetland in Jiaxing City from 2019 to 2021. The comparisons among the pollution indicators showed that the wetland reduced the pollutions and slowed down the fluctuations of pollution indicators, except for Do, TN and COD. The removal rates are different due to the causes of pollution indicators. The partial regression analysis to different influencing factors showed the water temperature were the main influencing factor to the turbidity, NH3-N, Fe with the partial correlation of 0.447, -0.631, 0.510, respectively. Precipitation showed the highest influence on Mn with the partial correlation of 0.323. Flow showed highest influence on COD with the partial correlation of -0.339. Both flow and water temperature were the highest influence factors on No2-N, CODMn, Do and TN. However, water purification agent was not the main influence factor on any pollution indicators. The research results are conducive to improving the understanding of water security in the Yangtze River Delta region.

Double-Layer MWCNTs@HPPS Photothermal Paper for Water Purification with Strong Acid-Alkali Corrosion Resistance.

Solar-driven interfacial evaporation technology has been identified as a promising method to relieve the global water crisis, and it is particularly important to design an ideal structure of the solar thermal conversion evaporation device. In this paper, hydrophilic polyphenylene sulfide (HPPS) paper with loose structure and appropriate water transmission performance was designed as the based-material, and multi-walled carbon nanotubes (MWCNTs) layer with excellent photothermal conversion performance was constructed to realize the high-efficiency solar-driven evaporation. Under tail swabbing mode, the cold evaporation surface on the back of the evaporator greatly improved the evaporation rate, cut off the heat transfer channel to bulk water, and achieved the maximum evaporation rate of 1.23 L/m2·h. Ethyl cellulose (EC) was introduced to adjust the water supply performance of HPPS layer, and a large specific surface area of cold evaporation was obtained, thus improving the water evaporation rate. In the simulation experiment of seawater desalination and dye wastewater treatment, it showed good water purification capacity and acid/alkali-resistance, which had great practical application significance.

Experimental Study on the Influence of Barrier Structures on Water Renewal Capacity in Slow-Flow Water Bodies

Artificial islands and viewing pavilions can act as barriers in slow-flow water bodies such as lakes and can be used together with water diversion projects to improve the water quality. In this study, based on the particle image velocimetry system, we carried out flume experiments to study the influence of the location and shape of barriers on the purification capacity of a slow-flow water body. We analyzed the velocity composition based on the information entropy H and the vector distributions, average velocity and water exchange rate η. The results reveal that the hydrodynamic characteristics are significantly optimized by barrier structures. η doubles if the barrier structure is reasonably designed, and it is positively correlated with the average velocity. In all cases, the highest η is recorded for a barrier shaped as a rectangular column and increases with the interaction area between the flow and structure. The water purification capacity and flow velocity gradually increase with increasing flow rate. The influence of the relative distance l between the inlet and the structure on η is non-monotonic. To achieve a higher η, the l for the rectangular column, triangular prism, and semi-cylinder should be 0.2–0.3, 0.2–0.3, and 0.3–0.55, respectively. The deflection angles and the ratio of lateral velocity to streamwise velocity of the deflection mainstream decrease with increasing l. H for the rectangular column is higher than that for other shapes. The results are of guiding significance for the layout of barrier structures and for the optimization of water landscapes in practical applications.

Effects of Bisphenol A Stress on Activated Sludge in Sequential Batch Reactors and Functional Recovery

This study assessed the toxic effects of bisphenol A (BPA) on the microbial community and the function of activated sludge in sequencing batch reactors (SBRs). The toxicity of BPA was mitigated through dosing sludge with Rhodococcus Req-001. BPA reduced the biomass of sludge, and the proportion of viable bacteria decreased with the aggravation of BPA pollution. BPA affected the secretion of extracellular polymeric substances (EPSs), increased the ratio of polysaccharide to protein, and deteriorated the sedimentation performance of sludge. BPA decreased the abundances of functional bacteria involved in the degradation of organic matter and water purification, including Polaromonas, Dechloromonas, and Nitrospira, and the water purification capacity of the reactor decreased. Req-001 enhanced the BPA removal efficiency by 15%, and increased ammonia nitrogen and phosphorus removal by 8.8% and 22.7%, respectively. The functional recovery ability of the sludge system and the high removal ability of Req-001 make it a promising specie for use in BPA bioremediation. This study combined the effect of BPA on activated sludge and reactor performance with the microbial community, clarified the toxic mechanism of BPA on activated sludge, and therefore provides a theoretical basis and potential solutions to help WWTPs cope with the toxic effects of BPA.

Molecular and biochemical effects on metabolism and immunity of Hyriopsis cumingii fed with four different microalgae

Hyriopsis cumingii has attracted attention because of its pearl production performance and water purification capacity. Realizing sustainable industrialized culture of H. cumingii or applying it to bivalve biomanipulation for controlling water eutrophication needs urgent studies about the selection of suitable algae and the effects of different microalgae on mussel physiology. To contrast molecular and biochemical effects of high-quality microalgal diets (Chlorella vulgaris, Navicula pelliculosa, and Cyclotella sp.) with toxic Microcystis aeruginosa on metabolism and immune physiology of H. cumingii, levels of related enzymes and genes were analyzed during the 28-day exposure period. Results showed that the Cyclotella sp. diet could significantly (p < 0.05) maintain higher levels of metabolic enzymes (glutamic oxaloacetate transaminase (GOT), glutamic pyruvate transaminase (GPT), pyruvate kinase (PK), and hexokinase (HK)) and genes (CPT1 and LDLR). C. vulgaris and N. pelliculosa treatments significantly (p < 0.05) reduced activities of these metabolic parameters. The M. aeruginosa treatment significantly (p < 0.05) enhanced levels of immune enzymes (alkaline phosphatase (AKP), superoxide dismutase (SOD), and catalase (CAT)) and genes (HcIL-17 and IAP) on day 1 or 7, and there was a significant (p < 0.05) reduction on day 28. Results suggested that Cyclotella sp. was the suitable algae for H. cumingii, followed by C. vulgaris and N. pelliculosa, and toxic algae caused metabolic disorders, immune injury, and poor physiological status. The study has practical significance in the sustainable cultivation of H. cumingii and provides a theoretical basis for bivalve biomanipulation in eutrophic water.

Drivers for primary producers’ dynamics: New insights on annual benthos pelagos monitoring in anthropised freshwater marshes (Charente-Maritime, France)

Wetlands, especially marshes, support many services such as carbon catchment control or water purification led by primary producers such as phytoplankton and microphytobenthos (PB). The impact of the sedimentary compartment, as source and sink of essential nutrients for the water column, is often neglected in the study of their dynamics and water purification capacity of the systems. This work compared monthly (between February 2020 and April 2021) the benthic and pelagic primary producers’ dynamics in two anthropised freshwater marshes (Marans and Genouillé), with the simultaneous follow-up of physico-chemical parameters of the water column and nutrient fluxes at the sediment-water (SWI) interface. It was suggested a strong contribution of phytoplankton (pumping) and the benthic compartment (denitrification) to the water purification of these two nitrates (NO3−)-rich marshes. Total phytoplankton production fluctuated between ∼5 (winter) and 1500 mg C m−3 d−1 (fall) at Marans and between 40 (winter) and ∼750 mg C m−3 d−1 (spring) at Genouillé. At Marans, soluble reactive phosphorus (SRP) benthic effluxes (-2.101 to -6.102 µmol m−2 d−1 in fall and summer, respectively) coincided with phytoplankton bloom periods. These effluxes were inhibited by NO3− penetration in the sediment (0 to 5.104 µmol m−2 d−1), by inhibiting iron respiration. At Genouillé, inhibition of SRP effluxes depended on denitrification rate and on P stocks in the sediment, where slight SRP effluxes (-101 µmol m−2 d−1) could have co-occurred with slight NO3− influxes (5.102 µmol m−2 d−1) in spring. The presence of PB (between 10–60 and 40–120 mg gsed−1 at Marans and Genouillé, respectively), suggested a strong contribution of the benthic compartment to the total primary production (benthic and pelagic through resuspension processes) in these environments. This work encourages to consider the benthos and the pelagos as a unicum to provide better sustainable management of such systems and limit eutrophication risks in coastal areas.