The Influence of Varying Algal Biomass On Contaminant Exposure in Benthic-Planktonic Mesocosms: Copper (Ii)

A series of mesocosms was exposed to a suite of light treatments and nutrient enrichment in order to generate algal communities of varying biomass. the influence of this biomass on the speciation of copper (II) was studied. Distribution coefficients (_Kd,Lkg-1) were relatively high (log_Kd = 5 to 7), indicative of robust trace metal sequestration, and were likely controlled by the particulate organic carbon content (foc). Differences in _Kd over time and among treatments were significant, as was the relationship between _Kd and foc. Fluorescence quenching was used to determine binding capacities (_Lt, M) and their associated binding constants (_Kcond,M^-1) in order to model the solid phase copper speciation. the _Kcond ranged between 2.1 and 5.2 × 10¹²M^-1, indicating a very strong copper-ligand complex, and was higher in mesocosms that received more light. the light _Lt increased over time, dramatically after the nutrient enrichment, but did not vary systematically among light treatments. _Lt ranged from 7.2 × 10- 7 to 4.9 × 10- 5 M. the large magnitudes of _Kd, _Kcond and _Lt ensured that greater than 97% of total copper in the mesocosms was complexed by organic matter. the total copper concentration ([Cu]_T, M) needed to reach a target dissolved copper concentration of 10^-12.5 M (pCu = 12.5) was determined for each mesocosm over time. [Cu]_T was between 8.02 × 10^-5 and 3.41 × 10^-2 M, and increased over time. the [Cu]_T normalized to the target pCu (Effective Dose Ratio, EDR) increased directly with increases in algal biomass, indicating a direct link between system productivity and copper exposure. Approximately 45% of the variance in EDR was explained by variance in total biomass, while the residual variance in EDR was due likely to differences in the strengths of particle associations and magnitude of binding capacities.     

The Freshwater Mussel Parreysia Favidens (Benson) As A Biological Indicator of Polonium - 210 in A Riverine System

The concentration of ²¹⁰Po, an alpha emitter from the natural uranium series was measured in the soft tissues (total), shell, and different organs - digestive glands, gills, mantle and foot - of the freshwater mussel, Parreysia favidens (Benson), collected from the river Kaveri, at Tiruchirapalli in South India. the analyses were made in three size groups based on shell length (Group 1: 2-4 cm; Group 2: 4-5 cm; Group 3: 5-6 cm). the soft tissues of the mussel accumulated higher concentrations of ²¹⁰Po (74.0-125.5 Bq kg^-1 fresh) than the shell (2.9-3.9 Bq kg^-1 fresh). Further, younger mussels (1 group) showed higher concentrations (125.5+2.0 Bq kg^-1 fresh) in total soft tissues than older ones (III Group) (74.0+1.6 Bq kg^-1 fresh); concentration factors were 1.59x 10⁵ in I group and 9.37 × 10⁴ in III group. the ²¹⁰Po was observed to be non-uniformly distributed among the internal organs, which maintained the following descending order with reference to ²¹⁰Po accumulation: digestive glands, ranging from 286.2+3.5 Bq kg^-1 fresh to 43+1.3 Bq kg^-1 fresh. the concentration of ²¹⁰Po in the mussels was distinctly higher than that in the grass, Echinochloa colonum (J. Koenig), and carp, Cirrhinus cirrhosa (Bloch), from the same river. These data indicate that younger mussels could be used as an excellent biological indicator of ²¹⁰Po and among soft tissues, digestive glands are preferable to other tissues to monitor the distribution of ²¹⁰Po in the riverine system.     

Discriminating zooplankton assemblages through multivariate methods: A case for a tropical polluted harbour and Bar-built estuary

A comparative study (June-July 2001) on zooplankton community structure amid polluted conditions in a stagnant harbour and relatively unaffected tidal estuary near Visakhapatnam, on the east coast of India, revealed a marked disparity in species composition and abundance. While the harbour supported a rich population of calanoids (46.4%), the estuary sustained mostly cyclopoids (55.2%). Univariate and multivariate techniques (species diversity, clustering, non-metric multi-dimensional scaling and one-way ANOSIM) revealed the existence of two differing zooplankton assemblages and associated water quality (similarity 50.6%). While the estuary is typified by high amounts of dissolved silica (67.4 ± 17.7 μmol l^-1) linked with monsoon influx, the harbour waters revealed abnormal levels of phosphate (40.9 ± 9.2 μmol l^-1) and nitrate (15.3 ± 5.41 μmol l^{- 1}) suggestive of intense eutrophication, caused by the discharge of fertilizer-factory waste and domestic sewage. On the basis of routines (e.g. BVSTEP, SIMPER) implemented in Plymouth Routines in Multivariate Ecological Research, it was possible to demonstrate that while species such as Oithona rigida, Oithona brevicornis, crustacean nauplii, gastropod veligers, Acartia spinicauda, and Acartia centrura played a key role in discriminating the zooplankton assemblage in the estuary, Acrocalanus spp. (mainly Acrocalanus gracilis) played a keyed role in harbour waters. Canonical Correspondence Analysis revealed species-environment relationships; for example, while the distribution of Oithona spp. and its associates in the estuary corresponded intimately with high silicate, temperature, and low salinity, it was high salinity, phosphate, and nitrate in the harbour channel that supported a different assemblage of copepods dominated by calanoids.     

Prediction of high-density polyethylene pyrolysis using kinetic parameters based on thermogravimetric and artificial neural networks

● Reducting the sampling frequency can enhance the modelling process. ● The pyrolysis of HDPE was investigated at three different heating rates. ● The average E_a and k₀ were calculated by Friedman, KAS, FWO, and CR methods. ● ANN was employed to predict the HDPE weight loss with the optimal MSE and R². Pyrolysis is considered an attractive option and a promising way to dispose waste plastics. The thermogravimetric experiments of high-density polyethylene (HDPE) were conducted from 105 °C to 900 °C at different heating rates (10 °C/min, 20 °C/min, and 30 °C/min) to investigate their thermal pyrolysis behavior. We investigated four methods including three model-free methods and one model-fitting method to estimate dynamic parameters. Additionally, an artificial neural network model was developed by providing the heating rates and temperatures to predict the weight loss (wt.%) of HDPE, and optimized via assessing mean squared error and determination coefficient on the test set. The optimal MSE (2.6297 × 10⁻²) and R² value (R² > 0.999) were obtained. Activation energy and pre-exponential factor obtained from four different models achieves the acceptable value between experimental and predicted results. The relative error of the model increased from 2.4 % to 6.8 % when the sampling frequency changed from 50 s to 60 s, but showed no significant difference when the sampling frequency was below 50 s. This result provides a promising approach to simplify the further modelling work and to reduce the required data storage space. This study revealed the possibility of simulating the HDPE pyrolysis process via machine learning with no significant accuracy loss of the kinetic parameters. It is hoped that this work could potentially benefit to the development of pyrolysis process modelling of HDPE and the other plastics.     

Unveiling the interaction mechanisms of key functional microorganisms in the partial denitrification-anammox process induced by COD

● The availability of PD-anammox was investigated with higher NO₃^––N concentration. ● NO₃^––N concentration affects NO₃^––N accumulation during denitrification. ● COD concentration is determinant for N removal pathways in PD-anammox process. ● The synergy/competition mechanisms between denitrifiers and anammox was explored. Partial denitrification-anammox (PD-anammox) is an innovative process to remove nitrate (NO₃^––N) and ammonia (NH₄⁺–N) simultaneously from wastewater. Stable operation of the PD-anammox process relies on the synergy and competition between anammox bacteria and denitrifiers. However, the mechanism of metabolic between the functional bacteria in the PD-anammox system remains unclear, especially in the treatment of high-strength wastewater. The kinetics of nitrite (NO₂^––N) accumulation during denitrification was investigated using the Michaelis-Menten equation, and it was found that low concentrations of NO₃^––N had a more significant effect on the accumulation of NO₂^––N during denitrification. Organic matter was a key factor to regulate the synergy of anammox and denitrification, and altered the nitrogen removal pathways. The competition for NO₂^––N caused by high COD concentration was a crucial factor that affecting the system stability. Illumina sequencing techniques demonstrated that excess organic matter promoted the relative abundance of the Denitratesoma genus and the nitrite reductase gene nirS, causing the denitrifying bacteria Denitratisoma to compete with Cadidatus Kuenenia for NO₂^––N, thereby affecting the stability of the system. Synergistic carbon and nitrogen removal between partial denitrifiers and anammox bacteria can be effectively achieved by controlling the COD and COD/NO₃^––N.     

Deciphering the effect of sodium dodecylbenzene sulfonate on up-flow anaerobic sludge blanket treatment of synthetic sulfate-containing wastewater

• UASB reactor can work efficiently with high COD/SO₄^2- ratios when SDBS exists. • Outcome of the competition between SRB and MPA was affected by SDBS. • Presence of SDBS makes methanogens with H₂/CO₂ as a substrate dominant. • Microbial diversity decreases in the presence of SDBS. In this study, the effects of organic sulfur on anaerobic biological processes were investigated by operating two up-flow anaerobic sludge blanket (UASB) reactors with sodium dodecylbenzene sulfonate (SDBS) as a representative of organic sulfur. The results indicated that the specific methanogenic activity (SMA) and chemical oxygen demand (COD) removal efficiency of R2 (with SDBS added) were higher than those of R1 (without SDBS) when the COD/SO₄²⁻ ratio was above 5.0. However, when the COD/SO₄²⁻ ratio was lower than 5.0, the sulfate reduction efficiency of R2 was higher than that of R1. These results and the observed SDBS transformation efficiency in anaerobic reactors indicate that low concentrations of SDBS accelerate methane production and the continuous accumulation of SDBS does not weaken the reduction of sulfate. Similarly, the calculated electron flux for a COD/SO₄²⁻ ratio of 1.0 indicates that the utilization intensity of electrons by sulfate-reducing bacteria (SRB) in R2 was 36.48% higher than that of SRB in R1 and exceeded that of methane-producing archaea (MPA) under identical working conditions. Moreover, the addition of SDBS in R2 made sulfidogenesis the dominant reaction at low COD/SO₄²⁻, and Methanobacterium and Methanobrevibacter with H₂/CO₂ as the substrate and Desulfomicrobium were the dominant MPA and SRB, respectively. However, methanogenesis was still the dominant reaction in R1, and Methanosaeta with acetic acid as the substrate and Desulfovibrio were the dominant MPA and SRB, respectively.     

上海市公园绿地常见落叶树木叶片汞浓度时空特征及环境意义

植物叶片汞浓度与大气气态单质汞(GEM/Hg0)浓度的线性关系表明叶片汞浓度大小可用于指示植物生长区内GEM浓度的高低水平.通过分析上海市绿地公园(25座)中常见落叶树木樱花、水杉、法桐叶片汞浓度的时空变化特征,探究区域内GEM含量水平及分布特征.2017年5-10月对7座公园中这3种树木叶汞浓度进行连续监测,结果显示...     

磷肥种类对李氏禾富集铜、铬的影响及其生理响应

植物修复是现下环境和生态领域研究的热门话题。环境中的铜、铬等重金属复合污染问题越发严重,在水环境修复和治理的方法中,植物修复技术的优越性越发显著。该文旨在加深磷对李氏禾累积重金属铜和铬复合污染的认识。施磷是一种重要的农艺措施,其在提高植物修复复合污染水体效率方面的效果不容忽视。该实验研究李氏禾(Leersia Hexandra Swartz)分别在磷酸氢二铵(DAP)、磷酸二氢铵(MAP)、磷酸氢钙(DCP)、过磷酸钙(SSP)4种磷肥的不同质量浓度(无磷0 mg·L^?1、低磷11.38 mg·L^?1、中磷22.76 mg·L^?1和高磷45.52 mg·L^?1),Cu(II)、铬(VI)质量浓度均为10 mg·L^?1的复合污染水体下的重金属累积影响和生理响应。结果表明:在中磷浓度下,施加SSP后李氏禾对铜、铬的富集能力最大,为0P处理组的1.8—3.4倍,均高于其他处理组且存在显著性差异(P<0.05)。在高磷浓度处理下,施加(NH4)2HPO4处理组李氏禾生物量为9.260 g·10 plants?1,株高为59.07 cm,叶绿素含量为4.889 mg·g^?1,可溶性蛋白含量为10.77 g·L?1,均高于其他处理组且达到显著性差异(P<0.05)。在中磷浓度处理下,SSP处理组李氏禾叶片中丙二醛(MDA)含量为1.251μmol·g?1,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的含量分别为4.765、3.077、10.16 U·mg^?1(以prot.计),均高于其他处理组且达到显著性差异(P<0.05)。适量施加磷肥可以有效地提高李氏禾的生物量,以及各组织对铜、铬的累积作用,这一结果提高了我们对磷在植物修复技术中的作用的认识。     

Removal of ammonium and nitrate through Anammox and FeS-driven autotrophic denitrification

● Simultaneous NH₄⁺/NO₃^– removal was achieved in the FeS denitrification system ● Anammox coupled FeS denitrification was responsible for NH₄⁺/NO₃^– removal ● Sulfammox, Feammox and Anammox occurred for NH₄⁺ removal ● Thiobacillus, Nitrospira , and Ca. Kuenenia were key functional microorganisms An autotrophic denitrifying bioreactor with iron sulfide (FeS) as the electron donor was operated to remove ammonium (NH₄⁺) and nitrate (NO₃⁻) synergistically from wastewater for more than 298 d. The concentration of FeS greatly affected the removal of NH₄⁺/NO₃⁻. Additionally, a low hydraulic retention time worsened the removal efficiency of NH₄⁺/NO₃⁻. When the hydraulic retention time was 12 h, the optimal removal was achieved with NH₄⁺ and NO₃⁻ removal percentages both above 88%, and the corresponding nitrogen removal loading rates of NH₄⁺ and NO₃⁻ were 49.1 and 44.0 mg/(L·d), respectively. The removal of NH₄⁺ mainly occurred in the bottom section of the bioreactor through sulfate/ferric reducing anaerobic ammonium oxidation (Sulfammox/Feammox), nitrification, and anaerobic ammonium oxidation (Anammox) by functional microbes such as Nitrospira, Nitrosomonas, and Candidatus Kuenenia. Meanwhile, NO₃⁻ was mainly removed in the middle and upper sections of the bioreactor through autotrophic denitrification by Ferritrophicum, Thiobacillus, Rhodanobacter, and Pseudomonas, which possessed complete denitrification-related genes with high relative abundances.     

Cultivation of Chlorella sp. HQ in inland saline-alkaline water under different light qualities

• Optimal growth of Chlorella in inland saline-alkaline water was achieved by blue LED. • Lipids of Chlorella sp. HQ were mainly composed of C16:0 and C18:2 under various LEDs. • The BiodieselAnalyzer^© software was used to evaluate the Chlorella biodiesel quality. • Chlorella sp. HQ was a high-quality feedstock for biodiesel production. Inland saline-alkaline water can be used for the low-cost cultivation of microalgae, but whether algal biomass under various light sources has the potential to produce biodiesel remains to be developed. Herein, the influence of different light-emitting diode (LEDs) light colors (blue, red, white, mixed blue-red, and mixed blue-white LED) on the growth performance, lipid accumulation, and fatty acid composition of Chlorella sp. HQ cultivated in inland saline-alkaline water was investigated. The highest algal density was obtained under blue LEDs at the end of cultivation, reaching 1.93±0.03 × 10⁷ cells/mL. White LEDs can improve biomass yield, total lipid yield, and triacylglycerol yield per algal cell. The main fatty acid components of Chlorella from inland saline-alkaline water were palmitic acid and linoleic acid. The BiodieselAnalyzer^© software was used to predict algal biodiesel quality by estimating different quality parameters. The cetane number, kinematic viscosity, and density of Chlorella biodiesel were 51.714–67.69, 3.583–3.845 mm²/s, and 0.834–0.863 g/cm³, respectively. This further proved that the Chlorella biomass obtained from inland saline-alkaline water has the potential to be used as a high-quality biodiesel feedstock.     

Trace Metal Uptake By Pichia Spartinae, an Endosymbiotic Yeast in the Salt Marsh Cord Grass Spartina Alterniflora

The ascosporogenous marine yeast Pichia spartinae is a dominant endosymbiont of the marsh grass Spartina alterniflora. Results of previous studies suggested that P. spartinae is involved in iron transport processes in the grass. of particular interest has been the mechanisms of metal uptake and metabolism by the yeast, and the ecological and plant biochemical significance of these processes. This investigation examined the uptake of iron and other metals (Zn, Cu, Cd, Ni, Pb, Cr) by P. spartinae, and provides data on possible mechanisms of this activity. the results suggest a) the yeast can assimilate divalent and trivalent forms of inorganic iron, as well as large organic-Fe(III) complexes, b) the uptake of inorganic trivalent iron under soluble iron-deficient conditions proceeded by a different mechanism than that of soluble Fe(II), with intracellular loadings of iron much increased under the former conditions; c) trivalent iron uptake is not mediated by hydroxamate siderophores at levels detectable by sensitive screening assays; d) the assimilation of some trace metals (Cu, Zn, Cd, Ni) is likely to be mediated by low molecular weight cysteine rich proteins, possibly metallothionein, and; e) siderophores from other fungi can provide iron for P. spartinae. the iron assimilation data suggested that multiple mechanisms are involved, and are influenced by the concentration and speciation of iron in the system. in general, iron assimilation mechanisms are comparable to those described for closely related yeasts, such as Saccharomyces cerevisiae. Among other things, these results indicated that future studies of trace metal mobilization and plant assimilation in salt marsh ecosystems must account for the activities of microbial symbionts associated with the plants.     

城市森林大气PM2.5中水溶性无机离子沉降特征

森林被誉为"地球之肺",在防霾治污方面有其独特不可替代的作用,不同树种沉降PM_2.5的功能有很大差别.本文选取代表性城市森林——奥林匹克森林公园为研究对象,设置垂直监测塔观测大气PM_2.5的浓度垂直分布,以考察不同季节城市森林对PM_2.5中各组分的影响.在冬季、春季和夏季各采集PM_2.5样品,分析并计算PM_2.5中Na⁺、NH₄⁺、K⁺、Mg2⁺、Ca2⁺、Cl^-、NO₃^-和SO₄^2-等典型水溶性无机离子的浓度.结果表明,PM_2.5中水溶性无机离子总浓度呈规律性变化特征:冬季((56.90±27.38)μg·m-3)>春季((46.69±12.24)μg·m^-3)>夏季((23.16±8.75)μg·m^-3).其中SO₄^2-和NO₃^-浓度和占PM_2.5主要水溶性无机离子总浓度的50%以上.3个季节中,除冬季外,在春季和夏季,8种离子有明显的垂直方向上的沉降,夏季的沉降速率高于春季,但是春季由于大气颗粒物浓度高,沉降通量高于夏季.NO₃^-和SO₄^2-垂直方向的沉降量在所有可溶性无机离子中最高.植被密度、叶面积指数、气象条件等因素对于PM_2.5的沉降特征有明显影响.     

Influence of arsanilic acid,Cu2+, PO43− and their interaction on anaerobic digestion of pig manure

The methanogenesis was severely inhibited with 0.46 mM ASA addition.PO₄³⁻ didn’t attenuate the methanogenesis inhibition in the existence of ASA.ASA was transformed to As(III), As(V), MMA and DMA in anaerobic digestion.Cu²⁺ mitigated the methanogenesis inhibition via impeding the degradation of ASA.Arsanilic acid (ASA), copper ion (Cu²⁺) and phosphate (PO₄³⁻) are widely used as feed additives for pigs. Most of these three supplemented feed additives were excreted in feces and urine. Anaerobic digestion is often used for the management of pig manure. However, the interaction of ASA with Cu²⁺ or PO₄³⁻ on anaerobic digestion is still not clear. In this study, the influence of ASA, Cu²⁺, PO₄³⁻ and their interaction on anaerobic digestion of pig manure and the possible mechanisms were investigated. The initial concentrations of ASA, Cu²⁺ and PO₄³⁻ were 0.46 mM, 2 mM and 2 mM in the anaerobic digester, respectively. The methanogenesis was severely inhibited in the assays with only ASA addition, only Cu²⁺ addition and ASA+ PO₄³⁻ addition with the inhibition index of 97.8%, 46.6% and 82.6%, respectively, but the methanogenesis inhibition in the assay with ASA+ Cu²⁺ addition was mitigated with the inhibition index of 39.4%. PO₄³⁻ had no obvious impacts on the degradation of ASA. However, Cu²⁺ addition inhibited the degradation of ASA, mitigating the methanogenesis inhibition. The existence of ASA would inhibit methanogenesis and generate more toxic inorganic arsenic compounds during anaerobic digestion, implying the limitation of anaerobic digestion for ASA- contaminated animal manure. However, the co-existence of ASA and Cu²⁺ could mitigate the inhibition. These results could provide useful information for the management of anaerobic digestion of pig manure containing ASA with Cu²⁺.     

The Relationship Between Iodine, Chlorinity, Ph, Reactive Phosphate, Nitrite and Organic Matter in the Coastal Water of Alexandria

Water samples were taken from 12 stations at El-Dikheila Harbour, El-Mex Bay, Western Harbour, Qayet Bey outfall, Eastern Harbour, El-Ibrahemiya, Gleem, Sidi Bishr and Mandara, during January, April, August and November 1995. the area lies between latitude 31˚ 8' and 31˚ 17' North and longitude 29˚ 47' and 30˚ East. the annual mean of chlorinity (11.69-20.5%₀), pH (7.9-8.3), reactive phosphate (0.31-2.24 μM), nitrite (0.18-1.98 μM), oxidizable organic matter (1.97-8.95 mgO₂ 1^-1), iodide (21.14-46.74 μg 1^-1) and iodate (4.61-2.04 μg 1^-1) were measured. Iodide content in water is three times higher than iodate. Iodide is positively correlated with chlorinity (r=0.65) and iodate (r=0.45), while it is negatively correlated with nitrite (r= -0.72), oxidizable organic matter (r= -0.55) and pH (r= -0.4).     

Fate and risk assessment of emerging contaminants in reclaimed water production processes

• PPCPs had the highest removal efficiency in A²O combined with MBR process (86.8%). • ARGs and OPFRs were challenging to remove (6.50% and 31.0%, respectively). • Octocrylene and tris(2-ethylhexyl) phosphate posed high risks to aquatic organisms. • Meta-analysis was used to compare the ECs removal in wastewater treatment. • Membrane treatment technology is the most promising treatment for ECs removal. Reclaimed water has been widely applied in irrigation and industrial production. Revealing the behavior of emerging contaminants in the production process of reclaimed water is the first prerequisite for developing relevant water quality standards. This study investigated 43 emerging contaminants, including 22 pharmaceuticals and personal care products (PPCPs), 11 organophosphorus flame retardants (OPFRs), and 10 antibiotic resistance genes (ARGs) in 3 reclaimed wastewater treatment plants (RWTPs) in Beijing. The composition profiles and removal efficiencies of these contaminants in RWTPs were determined. The results indicated that the distribution characteristics of the different types of contaminants in the three RWTPs were similar. Caffeine, sul2 and tris(1-chloro-2-propyl) phosphate were the dominant substances in the wastewater, and their highest concentrations were 27104 ng/L, 1.4 × 10⁷ copies/mL and 262 ng/L, respectively. Ofloxacin and sul2 were observed to be the dominant substances in the sludge, and their highest concentrations were 5419 ng/g and 3.7 × 10⁸ copies/g, respectively. Anaerobic/anoxic/oxic system combined with the membrane bioreactor process achieved a relatively high aqueous removal of PPCPs (87%). ARGs and OPFRs were challenging to remove, with average removal rates of 6.5% and 31%, respectively. Quantitative meta-analysis indicated that tertiary treatment processes performed better in emerging contaminant removal than secondary processes. Diethyltoluamide exhibited the highest mass load discharge, with 33.5 mg/d per 1000 inhabitants. Octocrylene and tris(2-ethylhexyl) phosphate posed high risks (risk quotient>1.0) to aquatic organisms. This study provides essential evidence to screen high priority pollutants and develop corresponding standard in RWTPs.     

Microbial electrolysis cells with biocathodes and driven by microbial fuel cells for simultaneous enhanced Co(II) and Cu(II) removal

Cobalt and copper recovery from aqueous Co(II) and Cu(II) is one critical step for cobalt and copper wastewaters treatment. Previous tests have primarily examined Cu(II) and Co(II) removal in microbial electrolysis cells (MECs) with abiotic cathodes and driven by microbial fuel cell (MFCs). However, Cu(II) and Co(II) removal rates were still slow. Here we report MECs with biocathodes and driven by MFCs where enhanced removal rates of 6.0±0.2 mg?L⁻¹?h⁻¹ for Cu(II) at an initial concentration of 50 mg?L⁻¹ and 5.3±0.4 mg?L⁻¹ h⁻¹ for Co(II) at an initial 40 mg?L⁻¹ were achieved, 1.7 times and 3.3 times as high as those in MECs with abiotic cathodes and driven by MFCs. Species of Cu(II) was reduced to pure copper on the cathodes of MFCs whereas Co(II) was removed associated with microorganisms on the cathodes of the connected MECs. Higher Cu(II) concentrations and smaller working volumes in the cathode chambers of MFCs further improved removal rates of Cu(II) (115.7 mg?L⁻¹?h⁻¹) and Co(II) (6.4 mg?L⁻¹?h⁻¹) with concomitantly achieving hydrogen generation (0.05±0.00 mol?mol⁻¹ COD). Phylogenetic analysis on the biocathodes indicates Proteobacteria dominantly accounted for 67.9% of the total reads, followed by Firmicutes (14.0%), Bacteroidetes (6.1%), Tenericutes (2.5%), Lentisphaerae (1.4%), and Synergistetes (1.0%). This study provides a beneficial attempt to achieve simultaneous enhanced Cu(II) and Co(II) removal, and efficient Cu(II) and Co(II) wastewaters treatment without any external energy consumption.     

Comparison of growth and lipid accumulation properties of two oleaginous microalgae under different nutrient conditions

This study compared the growth and lipid accumulation properties of two oleaginous microalgae, namely, Scenedesmus sp. LX1 and Chlorella sp. HQ, under different nutrient conditions. Both algal species obtained the highest biomass, lipid content and lipid yield under low-nutrient conditions （mBGll medium）. The biomass, lipid content and lipid yield of Scenedesmus sp. LX1 were 0.42g·L^-1, 22.5% and 93.8mg·L^-1, respectively. These values were relatively higher than those of Chlorella sp. HQ （0.30g·L^-1, 17.1% and 51.3mg·L^-1, respectively）. These algae were then cultivated in an SE medium that contained more nutrients; as a result, the biomass and lipid yield of Scenedesmus sp. LX1 reduced more significantly than those of Chlorella sp. HQ. Opposite results were observed in lipid and triacylglycerols （TAGs） contents. The cell sizes of both algal species under low-nutrient conditions were larger than those under high-nutrient conditions. Chlorella sp. HQ cells did not aggregate, but Scenedesmus sp. LX1 cells flocculated easily, particularly under low-nutrient conditions. In summary, low-nutrient conditions favour the growth and lipid production of both algae, but Scenedesmus sp. LX1 outperforms Chlorella sp. HQ.     

Preparation of nZVI embedded modified mesoporous carbon for catalytic persulfate to degradation of reactive black 5

• The MCNZVI is prepared as an interesting material for PS activation. • Graphitized carbon shells facilitate electron transfer from Fe⁰. • The MCNZVI exhibits excellent performance to degrade RB5 by ¹O₂. • The MCNZVI has high stability and reusability in the oxidation system. High-efficiency and cost-effective catalysts with available strategies for persulfate (PS) activation are critical for the complete mineralization of organic contaminants in the environmental remediation and protection fields. A nanoscale zero-valent iron-embedded modified mesoporous carbon (MCNZVI) with a core-shell structure is synthesized using the hydrothermal synthesis method and high-temperature pyrolysis. The results showed that nZVI could be impregnated within mesoporous carbon frameworks with a comparatively high graphitization degree, rich nitrogen doping content, and a large surface area and pore volume. This material was used as a persulfate activator for the oxidation removal of Reactive Black 5 (RB5). The effects of the material dosage, PS concentration, pH, and some inorganic anions (i.e., Cl⁻, SO₄²⁻) on RB5 degradation were then investigated. The highest degradation efficiency (97.3%) of RB5 was achieved via PS (20 mmol/L) activation by the MCNZVI (0.5 g/L). The pseudo-first-order kinetics (k = 2.11 × 10⁻² min⁻¹) in the MCNZVI/PS (0.5 g/L, 20 mmol/L) was greater than 100 times than that in the MCNZVI and PS. The reactive oxygen species (ROS), including ¹O₂, SO₄^·−, HO^·, and ·O₂⁻, were generated by PS activation with the MCNZVI. Singlet oxygen was demonstrated to be the primary ROS responsible for the RB5 degradation. The MCNZVI could be reused and regenerated for recycling. This work provides new insights into PS activation to remove organic contamination.     

Nitrate removal to its fate in wetland mesocosm filled with sponge iron: Impact of influent COD/N ratio

• CW-Fe allowed a high-performance of NO₃^‒-N removal at the COD/N ratio of 0. • Higher COD/N resulted in lower chem-denitrification and higher bio-denitrification. • The application of s-Fe⁰ contributed to TIN removal in wetland mesocosm. • s-Fe⁰ changed the main denitrifiers in wetland mesocosm. Sponge iron (s-Fe⁰) is a porous metal with the potential to be an electron donor for denitrification. This study aims to evaluate the feasibility of using s-Fe⁰ as the substrate of wetland mesocosms. Here, wetland mesocosms with the addition of s-Fe⁰ particles (CW-Fe) and a blank control group (CW-CK) were established. The NO₃^‒-N reduction property and water quality parameters (pH, DO, and ORP) were examined at three COD/N ratios (0, 5, and 10). Results showed that the NO₃^‒-N removal efficiencies were significantly increased by 6.6 to 58.9% in the presence of s-Fe⁰. NH₄⁺-N was mainly produced by chemical denitrification, and approximately 50% of the NO₃^‒-N was reduced to NH₄⁺-N, at the COD/ratio of 0. An increase of the influent COD/N ratio resulted in lower chemical denitrification and higher bio-denitrification. Although chemical denitrification mediated by s-Fe⁰ led to an accumulation of NH₄⁺-N at COD/N ratios of 0 and 5, the TIN removal efficiencies increased by 4.5%‒12.4%. Moreover, the effluent pH, DO, and ORP values showed a significant negative correlation with total Fe and Fe (II) (P<0.01). High-throughput sequencing analysis indicated that Trichococcus (77.2%) was the most abundant microorganism in the CW-Fe mesocosm, while Thauera, Zoogloea, and Herbaspirillum were the primary denitrifying bacteria. The denitrifiers, Simplicispira, Dechloromonas, and Denitratisoma, were the dominant bacteria for CW-CK. This study provides a valuable method and an improved understanding of NO₃^‒-N reduction characteristics of s-Fe⁰ in a wetland mesocosm.     

Algae (Raphidocelis subcapitata) mitigate combined toxicity of microplastic and lead on Ceriodaphnia dubia

• Micro-plastics (MPs) significantly increase Pb toxicity. • Algae reduce the combined toxicity of MP and Pb. • The toxicity increase comes from high soluble Pb and MP-Pb uptake. • The toxicity reduction might come from energy related pathway. Microplastics (MPs) have been recognized as a new class of emerging contaminants in recent years. They not only directly impact aquatic organisms, but also indirectly impact these organisms by interacting with background toxins in the environment. Moreover, under realistic environmental conditions, algae, a natural food for aquatic organisms, may alter the toxicity pattern related to MPs. In this research, we first examined the toxicity of MPs alone, and their effect on the toxicity of lead (Pb) on Ceriodaphnia dubia (C. dubia), a model aquatic organism for toxicity survey. Then, we investigated the effect of algae on the combined toxicity of MPs and Pb. We observed that, MPs significantly increased Pb toxicity, which was related to the increase in soluble Pb concentration and the intake of Pb-loaded MPs, both of which increased the accumulation of Pb in C. dubia. The presence of algae mitigated the combined toxicity of MPs and Pb, although algae alone increased Pb accumulation. Therefore, the toxicity mitigation through algae uptake came from mechanisms other than Pb accumulation, which will need further investigation.