Strategy for cost-effective BMPs of non-point source pollution in the small agricultural watershed of Poyang Lake: A case study of the Zhuxi River.

In recent years, Poyang Lake has been affected by severe agricultural non-point source (NPS) pollution, a global water pollution problem. The most recognized and effective control measure for agricultural NPS pollution is the strategic selection and placement of best management practices (BMPs) for critical source areas (CSAs). The present study employed the Soil and Water Assessment Tool (SWAT) model to identify CSAs and evaluate the effectiveness of different BMPs in reducing agricultural NPS pollutants in the typical sub-watersheds of the Poyang Lake watershed. The model performed well and satisfactorily in simulating the streamflow and sediment yield at the outlet of the Zhuxi River watershed. The results indicated that urbanization-oriented development strategies and the Grain for Green program (returning the grain plots to forestry) had certain effects on the land-use structure. The proportion of cropland in the study area decreased from 61.45% (2010) to 7.48% (2018) in response to the Grain for Green program, which was mainly converted to forest land (58.7%) and settlements (36.8%). Land-use type changes alter the occurrence of runoff and sediment, which further affect the nitrogen (N) and phosphorus (P) loads since sediment load intensity is a key factor affecting the P load intensity. Vegetation buffer strips (VBSs) proved the most effective BMPs for NPS pollutant reduction, and the cost of 5-m VBSs proved the lowest. The effectiveness of each BMP in reducing N/P load ranked as follows: VBS > grassed river channels (GRC) > 20% fertilizer reduction (FR20) > no-tillage (NT) > 10% fertilizer reduction (FR10). All combined BMPs had higher N and P removal efficiencies than the individual measures. We recommend combining FR20 and VBS-5m or NT and VBS-5m, which could achieve nearly 60% pollutant removal. Depending on the site conditions, the choice between FR20+VBS and NT + VBS is flexible for targeted implementation. Our findings may contribute to the effective implementation of BMPs in the Poyang Lake watershed and provide theoretical support and practical guidance for agricultural authorities to perform and direct agricultural NPS pollution prevention and control.

Variations in dissolved oxygen and aquatic biological responses in China's coastal seas.

Coastal areas can represent an ecological transition zone with the function of biodiversity conservation, and good water quality is fundamental to maintaining this function. In this study, we analyzed data from 2011 to 2020 to reveal the variation in dissolved oxygen (DO) and the aquatic biological response in China's coastal seas. Results showed that DO in coastal waters exhibited an upward trend from 2011 to 2020 because of reduction in terrestrial anthropogenic pollutant (TAP) input. In comparison with DO in other seas, the DO content in the East China Sea was lower owing to higher TAP input, i.e., the proportion of DO of <5 mg L-1 accounted for approximately 60% of the total. Species numbers, density, and the species diversity index of phytoplankton, zooplankton, and macrobenthos were different in the different sea areas because phytoplankton, zooplankton, and macrobenthos have different responses to changes in DO. In comparison with the species numbers of zooplankton and macrobenthos, the species numbers of phytoplankton were more significantly related to DO, and showed a negative linear relationship with a better DO environment (DO ≥ 5 mg L-1; r2 = 0.39, p < 0.01) and positive correlation with a poor DO environment (DO < 3 mg L-1; r2 = 0.52, p < 0.01). A better DO environment is conducive to increased density of macrobenthos. Studies have shown that a good DO environment contributes to coastal ecosystem health, and continuous control of TAP input is an effective means of ensuring DO recovery.

Multifunctional porous ß-cyclodextrin polymer for water purification.

Keeping water clean is of vital significance for human health and environmental protection. In order to remove organic micro-pollutants and natural organic substances in water bodies and kill pathogenic microorganisms simultaneously, this study synthesized a multifunctional porous ß-cyclodextrin polymer with a high specific surface area by introducing quaternary ammonium groups and rigid benzene rings, respectively, which was then polymerized with crosslinking agent-4,4'-bis (chloromethyl)-1,1'-biphenyl (BCMBP) in an ionic liquid system. The grafting of quaternary ammonium groups was beneficial for the removal of negative-charged humic acid (HA) and sterilization. The introduction of numerous rigid structures during benzylation and Friedel-Crafts alkylation reaction could significantly improve the porosity and specific surface area of the polymer, conducive to the exposure of cyclodextrin binding sites and contaminant adsorption. By changing the proportions of quaternization and benzylation, the structure and surface properties of the polymer could be adjusted, thus further regulating the adsorption performance. Compared with activated carbon, the polymer named BQCD-BP with a huge surface area of 1133 m2 g-1 prepared under optimized conditions showed outstanding adsorption performance and sterilization ability. The pseudo-second-order kinetic constant of BQCD-BP reached 1.2058 g·mg-1·min-1, which was approximately 50 times greater than that of activated carbon (0.0256 g·mg-1·min-1) under the same experimental condition. The adsorption capacity of BQCD-BP to HA was twice as high as that to AC, and the antibacterial ability of BQCD-BP was significant, achieving 90% at the dosage of 1g L-1. Moreover, the adsorption process was hardly affected by the hydrochemical conditions, and the polymer was easy to regenerate. In addition, the excellent adsorption and antibacterial performance of the polymer were also identified by natural water treatment. COD was almost completely removed, and the removal efficiency of TP reached 92% after contact with BQCD-BP. The sterilization rate of BQCD-BP to viable bacteria in complex water bodies reached 82%. Undoubtedly, BQCD-BP is a potential multifunctional water treatment material with reasonable design in the actual water purification.

Characterization of the distribution, source, and potential ecological risk of perfluorinated alkyl substances (PFASs) in the inland river basin of Longgang District, South China.

Previous studies of perfluorinated alkyl substances (PFASs) in receiving water bodies of typical industrial parks under the low-carbon development mode are scarce. In the present study, 18 PFASs were analyzed in surface water and sediment samples of the inland river basin in Longgang District in 2017. The ΣPFAS concentrations in surface water (drought and rainy periods) and sediment ranged from 15.17 to 948.50 ng/L, 11.56-561.14 ng/L, and 1.07-28.94 ng/g dw, respectively. Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) were the dominant pollutants in surface water, with maximum concentrations of 867.68 ng/L, 288.28 ng/L, and 245.09 ng/L, respectively. Meanwhile, PFOS, perfluoroundecanoic acid (PFUdA), PFBS, and perfluorodecanoic acid (PFDA) were the major PFASs in the sediment samples, with maximum concentrations of 9.83 ng/g dw, 11.86 ng/g dw, 5.30 ng/g dw, and 5.23 ng/g dw, respectively. In addition, PFOA and PFOS resulted from similar sources in sediment and surface water samples (P < 0.05). The risk quotient value (RQ) results showed that the control of PFOS in the treatment of pollutants in the inland river basin of Longgang District deserves more attention.

A review on China's constructed wetlands in recent three decades: Application and practice.

Constructed wetlands (CWs) have been introduced to and developed in China for environmental engineering over the most prosperous three decades (1990-2020). To study the origin, development process, and future trend of CWs, this review summarized a wide range of literatures between 1990 and 2020 by Chinese authors. Firstly, the publication number over years, research highlights, and the author contributions with the most published papers in this field were conducted through bibliometric analysis. Secondly, the most principal components of CWs, substrates and macrophytes were summarized and analyzed. Thirdly, the typical application cases from traditional CWs, pond systems to combined pond-wetland systems were presented. In China, CWs were predominately distributed in the east of the so-called 'Hu Huanyong Line'. Therefore CWs were limited by the socio-economic level and climatic conditions. It is unquestionable that the overall level of China's CWs has improved significantly, and one of the most prominent features has started towards the plural pattern development. There has been a trend of large-scale or low-cost CW application in the recent years. However, lifecycle research and management are required for better strategies in the future.

Spectroscopic investigation of the interaction between extracellular polymeric substances and tetracycline during sorption onto anaerobic ammonium-oxidising sludge.

In this study, the interaction between extracellular polymeric substances (EPS) and tetracycline during sorption onto anaerobic ammonium-oxidising (anammox) sludge was investigated. The results showed that EPS significantly enhanced the adsorption efficiency of tetracycline by sludge, and the adsorption data were better fitted with the pseudo-second-order kinetics model. Further, the concentration of proteins in the EPS decreased from 12.31 ± 0.42 to 6.82 ± 0.46 mg/gVSS for various tetracycline dosages (0-20 mg/L), whereas the concentration of polysaccharides did not change. Multiple spectroscopic methods were used to analyze the interaction between EPS and tetracycline. A three-dimensional excitation-emission matrix revealed that the fluorescence intensity of protein-like substances obviously decreased with the increasing addition of tetracycline. According to synchronous fluorescence spectra analysis, static quenching was the major quenching process and there was one type of binding site in the protein-like substances. Additionally, two-dimensional correlation spectroscopy showed that tryptophan-like aromatic protein was more susceptible to tetracycline binding than tyrosine-like aromatic protein. Moreover, the main functional groups involved in complexation of tetracycline and EPS were C-O, C-C and C-N (stretching vibration) and the pyrrole ring of the tryptophan side chain. This study provides useful information on the interaction between EPS and tetracycline and demonstrates the role of EPS in protecting microorganism from tetracycline in the anammox process.

MiR-190b impedes pancreatic ß cell proliferation and insulin secretion by targeting NKX6-1 and may associate to gestational diabetes mellitus.

BACKGROUND: The dysfunction of pancreatic ß cells is related to the occurrence of gestational diabetes mellitus (GDM). This study aimed to investigate the mechanism underlying the effects of miR-190b on pancreatic ß cell proliferation and insulin secretion. METHODS: Quantitative real-time PCR was used to detect miR-190b expression in placenta tissues from GDM patients. The effects of miR-190b on islet cells activity, proliferation, and insulin secretion were measured using MTT assay, BrdU staining, and ELISA. The relationship between miR-190b and NK6 homeobox 1 (NKX6-1) was ensured by dual luciferase reporter assay. RESULTS: MiR-190b was overexpressed in placenta tissues from GDM patients compared to normal pregnant woman. MiR-190b inhibitor inhibited the cell activity, proliferation, and insulin secretion of islet ß cells, while miR-190b overexpression had an opposite effect. Additionally, miR-190b negatively regulated NKX6-1 expression. Overexpression of NKX6-1 reversed the inhibitory effect of miR-190b-mimics on islet ß cell activity, proliferation, and insulin secretion. In mouse islets, knockdown of miR-190b promoted insulin secretion by up-regulating NKX6-1 expression. CONCLUSION: Silence of miR-190b accelerated pancreatic ß cell proliferation and insulin secretion via targeting NKX6-1, which might be a mechanism underlying the effects of miR-190b on the progression of GDM.

Pyrrhotite-sulfur autotrophic denitrification for deep and efficient nitrate and phosphate removal: Synergistic effects, secondary minerals and microbial community shifts.

Pyrrhotite-sulfur autotrophic denitrification (PSAD) system, using mixture of pyrrhotite and sulfur particle as electron donor, was studied through batch, column and pilot experiments. Treating synthetic secondary effluent at HRT 3 h, the PSAD system obtained the effluent with NO3--N 0.28 ± 0.14 mg·L-1 and without PO43--P to be detected. Thiobacillus was the most abundant autotrophic denitrification bacteria; autotrophic, heterotrophic and sulfate-reducing bacteria coexisted in the PSAD system; phosphate was mainly removed in forms of graftonite, dufrenite, ardealite. The H+ produced in the SAD could accelerate the PAD through promoting pyrrhotite dissolution, and iron ions produced in the PAD could accelerate the SAD through Fe3+/Fe2+ shuttle. Because of the synergistic effects between the pyrrhotite and sulfur, the PSAD system removed nitrate and phosphate deeply and efficiently. It is a promising way to meet the stringent nitrogen and phosphorus discharge standards and to recover phosphorus resources from wastewater.

Assessing biochar application to immobilize Cd and Pb in a contaminated soil: a field experiment under a cucumber-sweet potato-rape rotation.

Cd and Pb are common toxic contaminants prevailing in agricultural soils contaminated by mining activities. In this study, biochar was used to stabilize Cd and Pb contaminated soil for safe with three crops rotation condition within one year. Field experiments were carried out to investigate the effect of Litchi branch biochar (BC), pyrolyzed at 600 °C and applied at 4 rates [(0 t ha-1 (T0), 10 t ha-1 (T1), 20 t ha-1 (T2) and 30 t ha-1 (T3)]) on remediation of Cd and Pb in agricultural soil near Dabaoshan Mine in South China under a cucumber-sweet potato-rape rotation. The results showed that the application of BC can significantly increase the pH, cation exchange capacity and soil organic matter. After cultivation of crops, the pH values decrease gradually, with the biggest drop of 0.45 pH units in T3 treatment after rape cultivation. BC application increased the yield of three crops up to onefold to twofold in T3 treatment as compared to the control. The uptake of Cd and Pb in all three crops decreases with the increase in BC doses, which is mainly related to the decrease in bioavailable metals in their respective soil treatments. Under 1-year crops rotation, the remediation ability of BC still remains, while Cd and Pb can exhibit different risk to different crops. The data of this study can provide scientific suggestions for the selection of suitable crops and proper BC amount in remediation of heavy metal contaminated soil.

The climatic space of European pollen taxa.

Pollen data are widely used to reconstruct past climate changes, using relationships between modern pollen abundance in surface samples and climate at the surface-sample sites as a calibration. Visualization of modern pollen data in multidimensional climate space provides a way to establish that taxon abundances are well behaved before using them in climate reconstructions. Visualization is also helpful for ecological interpretation of variations in pollen abundance in space and time. Here, we present Generalized Additive Models for the distribution of 195 European pollen and pteridophyte spore taxa in a bioclimate space defined by seasonal temperatures (as mean temperature of the coldest month and annual growing degree days) and an annual moisture index. These models can be used to explore the realized climate niche of pollen taxa and to build statistical models for palaeoclimate reconstruction. The data set is released under a Creative Commons BY license. When using the data set, we kindly request that you cite this article.

Effect of ageing process on bisphenol A sorption and retention in agricultural soils amended with biochar.

The ageing of biochar and organic pollutant itself in soils can both influence the retention of organic pollutant in field soils. In this study, column experiments were adopted to determine the effect of ageing process on bisphenol A (BPA) sorption and retention in two typical Chinese agricultural soils with lychee branch biochar added. The effect of biochar ageing on soil organic matter (SOM) was specially investigated. Experimental results showed that the addition of biochar significantly increased the condensation and rigid of SOM, which could further increase with biochar ageing in soils. As a result, the addition of biochar significantly increased BPA sorption capacity (5.86 times and 3.30 times) and retention rate (13.60 times and 4.47 times) in fluvo-aquic soil and phaeozem respectively, while BPA sorption capacity and retention rate decreased obviously after biochar ageing in the two soils for 2 months as compared with the freshly incorporated biochar treatments, which may be attributed to the surface coverage and/or pore blockage of some sorption sites owning to DOC. With biochar incorporated, 2 months of BPA ageing increased BPA retention rate by about 4.50 times in both soils as compared with BPA newly spiked treatments. The results of this study could provide important parameters for prediction and control of organic pollutants such as BPA in soils.

Feasibility and safety of papermaking wastewater in using as ecological water supplement after advanced treatment by fluidized-bed Fenton coupled with large-scale constructed wetland.

Reuse of pulp-and-paper industry wastewater as reclaimed water is an effective way to mitigate water resource shortage. In this study, the feasibility and safety of papermaking wastewater for the use as ecological water supplement after the treatment by fluidized-bed Fenton (FBF) coupled with constructed wetland (CW), were investigated from laboratory-scale to large-scale field. The optimum pH, H2O2, H2O2/Fe2+ ratio and hydraulic retention time (HRT) of FBF were 3.5, 0.93 mL/L, 4 and 60 min, respectively, based on reduction of both total organic carbon (TOC) and genotoxicity. Furthermore, the safety of effluent was evaluated using SOS/umu assay and 8-hydroxy-2-deoxyguanosine (8-OHdG) in zebrafish. Results showed FBF followed by CW improved the conventional water quality indicators and reduced the toxicity. Average removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN), total phosphorus (TP) and colority were 87.3%, 93.59%, 51.73%, 84.75% and 95.86%, respectively. The equivalent concentration of 4-nitroquinoline 1-oxide (4-NQO-EQ) decreased from 30.6 ±â€¯1.6 µg/L in influent to 12.4 ±â€¯1.0 µg/L after treated by FBF, then decreased to 5.9 ±â€¯0.4 µg/L after treated by CW and to 3.2 ±â€¯0.3 µg/L after 12-km downstream self-purification. The chronic survival rates of 21-d zebrafish significantly increased from 0.0% in influent to 58.8 ±â€¯4.0% in effluent of CW and gradually increased to 68.8 ±â€¯2.6% after 12-km downstream self-purification. Similarly, 8-OHdG level in zebrafish decreased from 120.0 ±â€¯19.3 ng/L in effluent of ecological oxidation pond to 94.0 ±â€¯7.5 ng/L in effluent of CW and gradually decreased to 42.0 ±â€¯3.0 ng/L after 12-km downstream self-purification. The study concluded that FBF-CW is an efficient detoxication and water quality improvement technology for papermaking wastewater to be used as an ecological water supplement.

Glyphosate and nutrients removal from simulated agricultural runoff in a pilot pyrrhotite constructed wetland.

Pyrrhotite is often considered as a gangue mineral, and discarded in mine wastes and tailings. Glyphosate and fertilizer, often excessively used in agriculture, flow into water bodies with agriculture runoff, and cause pollution of water bodies. In this study, the pyrrhotite was used as a substrate in a pilot constructed wetland (CW) to remove the glyphosate and nutrients from simulated agriculture runoff. In nearly one year, the pilot pyrrhotite constructed wetland (Pyrr-CW) removed 90.3 ±â€¯6.1% of glyphosate, 88.2 ±â€¯5.1 of total phosphorus (TP) and 60.40 ±â€¯5.60% of total nitrogen (TN) on average, much higher than the control CW. The abundances of sulfur-oxidizing bacteria, such as Sulfurifustis, Sulfuriferula and Thiobacillus, were much higher in the Pyrr-CW than those in the control CW. In the Pyrr-CW goethite was produced by pyrrhotite aerobic oxidation (PAO) and pyrrhotite autotrophic denitrification (PAD) continuously and spontaneously. Higher glyphosate and TP removals were resulted from adsorption on the goethite produced, and higher TN removal was attributed to the PAD. High glyphosate and nutrients removal could keep a long term until the pyrrhotite in the Pyrr-CW was used up. The phosphorus (P) sequestered in the Pyrr-CW existed mainly in organic P, (Fe + Al)P and (Ca + Mg)P, and their order was (Fe + Al)P > organic P > (Ca + Mg)P. No heavy metal ions released from the Pyrr-CW. With higher and lasting removal rate, and lower cost, the Pyrr-CW is a promising technology for simultaneous glyphosate and nutrients removal from agricultural runoff and wastewater.

[Control of Sludge Bulking Caused by Unknown Reason Through FeCl3 Coupled with Biochemical Methods].

Filamentous bulking could commonly influence effluent water quality in sewage treatment plants. Existing technologies are slowly effective, time consuming, and poorly adaptable. For now, enhancing organics substrates (COD) and dissolved oxygen (DO) concentration, adding FeCl3 into the reactor, and maintaining alternant aeration conditions are common methods to control filamentous bulking, but the effects of coupling techniques on the control of bulking are rarely reported. In this study, the filamentous bulking resulting from unintentionally erupted Candidatus Saccharibacteria was controlled by FeCl3 coupled with biochemical methods, which transforming step-feed A/O processes to the SBR process in the emergency by increasing DO to (7.45±0.49) mg·L-1 during aeration, enhancing COD to (332.73±106.06) mg·L-1, and adding FeCl3 into the reactor to set the starting concentration to 120 mg·L-1. As the results showed, FeCl3 coupled with the biochemical method quickly counteracted the bulking sludge mainly composed of Candidatus Saccharibacteria caused by unknown reason, while the Sludge Volume Index dropped from 274 mL·g-1 to 56 mL·g-1 within 14 days. The relative abundance of Candidatus Saccharibacteria decreased from 97.64% to 32.67% at the genus level because FeCl3 coupled with the biochemical method inhibited growth of Candidatus Saccharibacteria. Meanwhile, effluents of both COD and PO43--P met the effluent requirements of the I-A discharge standard in China and removal efficiency of NH4+-N increased from 65.33% to 74.65%. The results showed that FeCl3 coupled with the biochemical method exhibited good performance in the control of bulking caused by unknown reasons.

Preferential Alternatives to Returning All Crop Residues as Biochar to the Crop Field? A Three-Source 13C and 14C Partitioning Study.

The simultaneous effects of biochar on soil organic matter (SOM, C4) and sweet potato (SP) residue (Ipomoea batatas, C3) mineralization were studied over 180 days via 13C and 14C isotopic label partitioning. Upon concomitant SP residue addition, biochar mineralization decreased by 11% of the total added biochar-C. Compared to positive priming effects induced by biochar amendment alone on SOM (0.46 mg C g-1 soil) at 180 days, amendment solely with SP residues induced significantly larger effects (1.5 mg C g-1 soil). Combination biochar and SP residue addition reduced SOM mineralization by 20.5% and increased SP residue mineralization by 10.1%. Biochar addition caused preferential uptake of SP residues over SOM by microbes. Thus, the lower priming effects on SOM and CO2 emission induced by biochar amendment with or without SP residues compared to that from SP residue addition alone may result in crop residues being partly pyrolyzed to biochar in the cropland.

Sulfur-siderite autotrophic denitrification system for simultaneous nitrate and phosphate removal: From feasibility to pilot experiments.

Siderite (FeCO3) is one kind of abundant and cheap carbonate minerals, but it has never been used as inorganic carbon sources and pH buffer in the sulfur autotrophic denitrification before. In this study, sulfur-siderite autotrophic denitrification (SSAD) system was formed. Batch, column and pilot experiments of the SSAD system showed that siderite could provide inorganic sources and pH buffer for sulfur autotrophic denitrification. The optimal volume ratio of sulfur and siderite was 1:3 for the SSAD system. Siderite could not be used as an electron donor by the sulfur autotrophic denitrifiers. The SSAD column removed 28 mg/L NO3--N and 3.1 mg/L PO43--P completely at 12 h HRT. The SSAD pilot biofilter during treating secondary effluent obtained stable NO3- and PO43- removal, and controlled effluent NO3--N and PO43--P around 4 and 0.2 mg/L, respectively, at 4 h HRT, and no blocking occurred in operation of 401 days. In the SSAD system, the main bacteria were Thiobacillus (67.8%), Sulfurimonas (20.0%), and Simplicispira (3.5%); and Sulfurimonas (29.4%), Ferritrophicum (15.2%), and Thiobacillus (10.3%) during treating synthetic wastewater and secondary effluent, respectively. PO43- was removed through iron phosphate precipitate. The SSAD system was a promising way to remove NO3- and PO43- simultaneously from wastewater lack of organic carbon sources.

Impacting Microbial Communities and Absorbing Pollutants by Canna Indica and Cyperus Alternifolius in a Full-Scale Constructed Wetland System.

Wetland plants that cover the wetlands play an important role in reducing pollutants. The aim of this study was to investigate the effect of two plant species on microbial communities and nitrogen-removal genes and to evaluate the contributions of absorbing pollutants by Canna indica (CI) and Cyperus alternifolius (CA) to the removal performance in both a vertical subsurface flow constructed wetland and a horizontal subsurface flow constructed wetland, which were part of a full-scale hybrid constructed wetland system. The microbial assemblages were determined using 16S rRNA high-throughput sequencing. Results showed that the presence of CI and CA positively affected microbial abundance and community in general and which was positive for the total bacteria and ammonia nitrogen removal in the CWs. The higher abundance of Nitrospirae appeared in the non-rhizosphere sediment (NRS) than that in the rhizosphere sediment (RS). More denitrification genes were found in NRS than in RS. The copy numbers of narG, nirS and nosZ genes for CA were higher than those for CI. Wetland plant species can significantly (P < 0.05) affect the distribution of microbial communities in RS. Plant selection is important to promote the development of microbial communities with a more active and diverse catabolic capability and the contribution of plant absorption to the overall removal rate of wetland system can be neglected.

Nutrient removal through pyrrhotite autotrophic denitrification: Implications for eutrophication control.

This study investigated nutrient removal kinetics and main influencing factors of natural pyrrhotite autotrophic denitrification (PAD), and nutrient removal performance and the microbial community in the PAD biofilter (PADB). Results demonstrated that both NO3- and PO43- in wastewater were nearly completely removed, and biological N removal and chemical P removal took place simultaneously in the PAD process. NO3- removal kinetics of the PAD can be described with half-order kinetics. The PAD was effective across a wide temperature range of 11-34 °C, initial NO3--N range of 13-52 mg·L-1 and PO43--P below 60 mg·L-1. Both NO3- and PO43- decreased gradually with wastewater flowing along the PADB. The PADB operation results show that at 12 h HRT, when the PADB treated wastewater containing 30.95 ±â€¯0.97 mg·L-1 of NO3- and 3.02 ±â€¯0.10 mg·L-1 of PO43--P, the effluent contained 1.15 ±â€¯2.08 and 0.09 ±â€¯0.11 mg·L-1 of NO3--N and PO43--P on average, respectively. In the PADB the dominant bacteria were Thiobacillus and Sulfurimonas, which used pyrrhotite as the electron donor to reduce NO3-. The relative abundance of Thiobacillus at the bottom of the PADB increased from 0.81% to 58.65% and that of Sulfurimonas decreased from 97.22% to 12.30%, with exposure to pyrrhotite. From the bottom to the top of the PADB, the relative abundance of Thiobacillus increased from 58.65% to 86.23% and Sulfurimonas decreased from 12.30% to 0.52%. Technologies based on the PAD are promising ways to control eutrophication.

Natural pyrite to enhance simultaneous long-term nitrogen and phosphorus removal in constructed wetland: Three years of pilot study.

The searches for suitable substrates with high capacity for phosphorus (P) removal and promoting denitrification for enhancing nitrogen (N) removal have been a key work in constructed wetlands (CWs) research in the past several decades. But few substrates enhancing simultaneous long-term N and P removal in CWs have been found before. In this study, two subsurface flow pilot-scale wetlands using natural pyrite and limestone as substrates were constructed. After 3 year of operation, we found that pyrite had no negative effects on growth of reeds, removals of chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N), but enhanced long-term total nitrogen (TN) and total phosphorus (TP) removals in constructed wetland. In the three years, the average TP and TN removals of pyrite constructed wetland (PCW) were 87.7 ± 14.2% with 0.25 ± 0.20 mg/L of average effluent TP and 69.4 ± 21.4% with 4.0 ± 3.2 mg/L of average effluent TN, respectively. The main P form in the PCW was (Fe + Al)-bound P. The mechanisms of the PCW with enhanced simultaneous long-term N and P removals were anaerobic and aerobic oxidations of pyrite. The main bacteria were Anaeromyxobacter (4.9%), Ramlibacter (4.8%), Defluviicoccus (4.2%), Azoarcus (3.7%), Geobacter (3.4%), and they were highly related to anaerobic and aerobic oxidation of pyrite in the PCW.

Debromination of Hexabromocyclododecane by Anaerobic Consortium and Characterization of Functional Bacteria.

A microbial consortium which can efficiently remove hexabromocyclododecane (HBCD) under anaerobic condition have been successfully enriched over 300 days. Under the optimal conditions, the degradation efficiency was 92.4% removal after treatment of 12 days with original addition of 500 µg/L HBCD, yielding 321.7 µg/L bromide in total as well. A typical debromination product, dibromocyclododecadiene (DBCD), was detected during the degradation process. The debromination profiles of three main HBCD diastereomers fitted well with first-order model (R2: 0.96-0.99), with the rate constants ranging from 1.3 × 10-1 to 1.9 × 10-1. The microbial community analysis by high throughput sequencing showed that the composition of the microbial communities varied dynamically with time and the population of functional bacteria increase sharply after enrichment. The population of Bacteroidetes increased from 5 to 47%. And some bacteria which are relatively minority in population at the beginning, such as Azospira oryzae (OTU2), Microbacterium (OTU13), and Achromobacter insolitus (OTU39) increased more than 22 times after enrichment (from 0.5 to 13%, 12%, and 11%, respectively). However, no reported dehalogenating bacteria were found after enrichment. And the contribution for debromination may come from new dehalogenating bacteria. All in all, the present study provided in-depth information on anaerobic microbial communities for HBCD removal by debromination.