Search

In this research, the adaptive event-triggered neural network controller design problem is investigated for a class of state-constrained pure-feedback fractional-order nonlinear systems (FONSs) with external disturbances, unknown actuator saturation, and input delay. An auxiliary compensation function based on the integral function of the input signal is presented to handle input delay. The barrier Lyapunov function (BLF) is utilized to deal with state constraints, and the event-triggered strategy is applied to overcome the communication burden from the limited communication resources. By the utilization of a backstepping scheme and radial basis function neural network, an adaptive event-triggered neural state-feedback stabilization controller is constructed, in which the fractional-order dynamic surface filters are employed to reduce the computational burden from the recursive procedure. It is proven that with the fractional-order Lyapunov analysis, all the solutions of the closed-loop system are bounded, and the tracking error can converge to a small interval around the zero, while the state constraint is satisfied and the Zeno behavior can be strictly ruled out. Two examples are finally given to show the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This article focuses the event-triggered adaptive finite-time control scheme for the states constrained fractional-order nonlinear systems (FONSs) under uncertain parameters and external disturbances. The backstepping scheme is employed to construct the finite-time controller via a series of barrier Lyapunov function (BLF) to solve that all the state constraints are not violated. Different from the trigger condition with fixed value, the event-triggered strategy is applied to overcome the communication burden of controller caused by the limited communication resources. By utilizing fractional-order Lyapunov analysis, all variables in the resulted system are proven to be bounded, and the tracking error converges to the small neighborhood around origin in finite time and without the Zeno behavior. Finally, the effectiveness of the proposed control scheme is verified by the simulation analysis of a bus power system. [ABSTRACT FROM AUTHOR]

In this article, an event-triggered adaptive fuzzy finite-time dynamic surface control (DSC) is presented for a class of strict-feedback nonlinear fractional-order systems (FOSs) with full-state constraints. The fuzzy logic systems (FLSs) are employed to approximate uncertain nonlinear functions in the backstepping process, the dynamic surface method is applied to overcome the inherent computational complexity from the virtual controller and its fractional-order derivative, and the barrier Lyapunov function (BLF) is used to handle the full-state constraints. By introducing the finite-time stability criteria from fractional-order Lyapunov method, it is verified that the tracking error converges to a small neighborhood near the zero and the full-state constraints are satisfied within a predetermined finite time. Moreover, reducing the communication burden can be guaranteed without the occurrence of Zeno behavior, and the example is given to demonstrate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]

Soil net nitrogen (N) mineralization is a key biogeochemical process influencing plant available N and net primary productivity in terrestrial ecosystems. However, the spatial variations and controlling factors of soil net N mineralization (RPNM) in arid and semi‐arid grasslands are less studied and unclear.In this study, we investigated the soil RPNM by performing a laboratory incubation experiment. Soil samples were collected from 30 sites in three east–west transects on the Inner Mongolia Plateau (MP), Loess Plateau (LP) and Tibetan Plateau (TP) along a 3200 km arid and semi‐arid grassland gradient, with each transect containing three different grassland types (meadow steppe [MS], typical steppe [TS] and desert steppe [DS], respectively).Results showed that the average RPNM values ranged from −0.37 to 1.29 mg N kg−1 day−1, with a significantly lower RPNM found in the DS (0.08 ± 0.01 mg N kg−1 day−1) compared with those in the MS (0.30 ± 0.03 mg N kg−1 day−1) and in the TS (0.33 ± 0.03 mg N kg−1 day−1) in the MP and LP transects (p < 0.05). This difference could be explained by variations in climatic and soil factors, such as hydrothermal index (HT), the soil pH, soil organic matter (SOM) and precipitation. However, no significant differences in RPNM were found among different grassland types in the TP transect, possibly due to the similarly low microbial activity, as indicated by the microbial biomass carbon values. Across all three grassland transects, HT, SOM and microbial variables were the major factors controlling RPNM, which together explained 20.7% of the variation in RPNM. Further structural equation model analysis indicated HT was an integral predictor of RPNM, directly or indirectly via SOM, under different conditions of precipitation and temperature.Our findings provide field evidence and parameters for biogeochemical cycling to better predict future N transformation processes under changing precipitation and temperature regimes across a wide range of arid and semi‐arid grassland ecosystems. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Bacterial myocarditis is a key cause leading to myocardial damage and cardiac dysfunction. Mesencephalic astrocyte-derived neurotrophic factor (MANF) has been found to be an anti-inflammatory factor. This study is to explore the effect of MANF on LPS-induced myocardial inflammation and macrophage differentiation. The myocarditis mouse model was constructed by LPS treatment. Myocardial damage and serum inflammatory factors were evaluated by ELISA. RT-qPCR was used to detect mRNA of M1/M2 macrophage markers. Western blot, immunohistochemical, and immunofluorescent staining were used to examine myocardial M1/M2 macrophages and NF-κB activation. Mono-macrophage-derived MANF deficiency enhanced LPS-induced inflammatory response and increased M1 macrophages in myocardium tissues, further causing more severe myocardial injury and lower survival rate of mice. Also, LPS-induced myocardial NF-κB activation was strengthened after mono-macrophage-derived MANF knockout. Mono-macrophage-derived MANF inhibits bacterial myocarditis and myocardial M1 macrophage differentiation, which is potential to be used for bacterial myocarditis treatment clinically. [ABSTRACT FROM AUTHOR]

In contrast to the calibration of an engine volumetric efficiency map (or lookup tables) from steady-state data, a method for the identification of the engine volumetric efficiency map using transient condition data is developed in this article, which can reduce the time and cost of engine map calibration. To expediently identify the map parameters, the mathematical description of the volumetric efficiency for a spark ignition (SI) gasoline engine is approximated in terms of a piecewise bilinear interpolation model with unknown map parameters, which can be rewritten as a dot product between a regression vector and a parameter vector using a membership function. With the combination of a map regression model and an SI gasoline engine air path dynamic model, a finite-time adaptive observer is designed to estimate the constant map parameters, for which the parameter estimation error information is explicitly derived. To guarantee the convergence of the identification for all map parameters, a trajectory scheme of the transient condition data from the map input that passes through all of the interpolation regions is introduced. The performance of the proposed algorithm is validated against transient condition data generated by the engine simulation software enDYNA provided by Tesis. It is shown that the volumetric efficiency map of an SI gasoline engine simulated with enDYNA is approximated acceptably by the proposed method. [ABSTRACT FROM AUTHOR]

The high-density acquisition technique can improve subsurface imaging accuracy. However, it increases production cost rapidly and limits the wide application in practice. To solve this issue, the high productivity blending acquisition technology has emerged as a promising way to significantly increase the efficiency of seismic acquisition and reduce production cost. The great challenge of the blending acquisition technology lies in the severe interference noise of simultaneous sources. Therefore, the success of the blending acquisition technology relies heavily on the effectiveness of separating effective energy from the blended noise. We propose a blended noise suppression approach by using a hybrid median filter, normal moveout (NMO), and complex curvelet transform (CCT) approach. First, median filter is applied to original data after NMO correction. Second, the CCT-based thresholding denoising method is used to extract the remained effective energy from the data after median filtering to get the preliminary de-blended result. Next, the updated data are obtained by subtracting the pseudo-de-blended data of the de-blended result from the original data, and the process iterates. Last, the final de-blended result is obtained by adding the retrieved energy at each iteration until the signal-to-noise ratio satisfies the desired level. We demonstrate the effectiveness of the proposed approach on simulated synthetic and field data examples. [ABSTRACT FROM AUTHOR]

The necessity on controlling internal P pollution has been widely reported for lake restoration; thus far, cutting the migrations of soluble P from sediment to overlying water, especially under anoxic condition, is the main target of the internal P pollution control to achieve favorable ecological responses in lake. Here, according to the types of P directly available by phytoplankton, phytoplankton-available suspended particulate P (SPP) pollution, which mainly occurs under aerobic condition and due to sediment resuspension and soluble P adsorption by suspended particle, is found to be the other kind of internal P pollution. The SPP has long been a key index for environmental quality assessment, which could be indirectly reflected by the developed various methods for phytoplankton-available P pool analysis; also, the P has been demonstrated to be a major cause of phytoplankton breeding, typically in shallow lakes. Importantly, compared to the soluble P, SPP pollution clearly has more complicated loading pathways and P activation mechanisms and involves in different fractions of P, even part of which are with relatively high stability in sediment and suspended particle, leading to the potential control measures for the pollution being more complex. Considering the potential differences of internal P pollution among various lakes, this study is therefore calling for more research to focus on regulating phytoplankton-available SPP pollution. Recommendations are also offered to bridge knowledge gap of the regulation to design proper measures for lake restoration. [Display omitted] • Internal P pollution is divided based on types of P available by phytoplankton. • The pollution of suspended particulate P (SPP) is different from that of soluble P. • This study is calling for more research on regulating phytoplankton-available SPP. • Recommendations are offered to bridge knowledge gap for SPP regulation. [ABSTRACT FROM AUTHOR]

This study proposed a scheme for drinking water treatment residue (DWTR) pretreatment to eliminate concerns about potential unfavorable effects caused by excessive release of nutrients (typically N) during recycling in restoration of a water environment with relatively low pollution (e.g., eutrophic surface water). Inspired by soil washing, the pretreatment scheme was based on washing processes; correspondingly, the N desorption characteristics, possibility of recycling solutions for subsequent desorption, and variations in DWTR adsorption capabilities were investigated. The results showed that N, mainly as ammonia N (NH 4 +-N), was quickly desorbed from DWTR; the concentrations of desorbed NH 4 +-N were an order of magnitude higher than those of nitrate N (NO 3 −-N). After six rounds of desorption, most ion-exchangeable NH 4 +-N was desorbed, and NH 4 +-N released from the DWTR (after the desorption test) declined markedly from 11.1 to <0.70 mg L−1 in initial column tests for surface water treatment. The same desorption characteristics of NH 4 +-N were observed for six DWTR collected from Australia, Ireland, and China, respectively; after N desorption, the adsorption capability of the six DWTR changed negligibly. Furthermore, electrochemical treatment was found to be effective in removing desorbed NH 4 +-N in solutions from DWTR; the treated solutions can be recycled for subsequent desorption without weakening NH 4 +-N desorption efficiencies, although NH 4 +-N removal efficiencies by electrochemical treatment tended to decline as the recycling of solutions increased to five rounds. Overall, the pretreatment scheme is scientifically feasible and can be applied and optimized based on remediation requirements in practical scenarios. • The ion-exchangeable N, mainly as NH 4 +-N, was quickly desorbed from DWTR. • Similar N desorption were observed for DWTR collected from different countries. • After N desorption, the adsorption capability of DWTR changed little. • The washing pretreatment is feasible for DWTR reuse in surface water restoration. [ABSTRACT FROM AUTHOR]

Abstract: The loading of La can substantially enhance the adsorption capability of drinking water treatment residue (DWTR) for better recycling. Normally, the modification was based on incubation of DWTR and La solution at a certain ratio, following by solid-liquid separation and drying processes. This study attempted to simplify La loading procedures by adopting high ratio of DWTR and La solution to eliminate the solid-liquid separation, aiming to promote the potential actual production. According to the results of the short- (2 d) and long-term (30 d) P adsorption tests, the N 2 gas sorption and desorption analysis, the X-ray photoelectron spectroscopy analysis, and the metal fractionation, the substantial enhanced adsorption capability of the modified DWTR was maintained and the La loading mechanisms to DWTR changed little after eliminating solid-liquid separation processes during modification; typically, La loading increased the initial P adsorption rates from 1.00 (raw DWTR) to 6.08 and 6.03 mg g−1 d−1 for the modified DWTR with and without the separation processes. Furthermore, the DWTR before and after modification had little unfavorable effect on the survival of snail Bellamya aeruginosa , while eliminating the separation processes tended to reduce the bioavailability of Al, Fe, and La in the modified DWTR. These results demonstrated that solid-liquid separation was not the key step for DWTR modification and that the developed simple modification method was feasible for La loading to DWTR, promoting the beneficial recycling in environmental remediation. Highlights • This study simplified a normal La loading process for DWTR modification. • The substantial enhanced initial adsorption by modified DWTR was still achieved. • The La loading mechanisms to DWTR by the simple method changed little. • The Al, Fe and La bioavailability decreased in DWTR modified by the simple method. [ABSTRACT FROM AUTHOR]

Abstract The separation and recovery of pollutant-loaded magnetic carbon materials from organic contaminated environment is recently concerned, but the change of sorption ability and mechanism of activated carbon and biochar caused by magnetic particles modification still need to be explored. Here, the magnetic modification of two coconut shell-, coal-derived activated carbon and one biochar, and its effect on the removal of phenol from water were investigated. Magnetic activated carbon (MAC) and magnetic biochar (MBC) were prepared by co-precipitation. The increase of mass magnetic susceptibilities and energy dispersive X-ray spectroscopy (EDX) analysis showed that magnetic particles were successfully coated on the surface of virgin carbonaceous materials (VCMs). Magnetic modification enhanced the surface area and pore volume of activated carbon, and preserved those structure properties of biochar. Magnetic activated carbon had lower adsorption rates (10.641 g mg−1·min−1) than virgin activated carbon (20.575 g mg−1·min−1) while magnetic biochar exhibited higher adsorption rate (0.618 g mg−1·min−1) compared with virgin biochar (0.040 g mg−1·min−1), which were related to mass transport process. Data from Langmuir model results suggested that maximum adsorption capacities of three carbon adsorbents were increased by magnetic modification. The enhanced removal of phenol after magnetizing process may attribute to the increase of specific surface area and pore volume. Among VCMs/MCCs, magnetic coconut shell-derived carbon material with 951.84 m2/g surface area exhibited the most organic contaminant sorption performance. This finding gives insight into the adsorption mechanism of magnetic AC/BC for phenol, and provides a guidance to choose the appropriate magnetic composites to remove the organic contaminant effectively. Highlights • Magnetic particles were successfully coated on carbon materials surface. • Magnetic modification retained/increased BET surface area of adsorbents. • Magnetic coconut shell activated carbon had phenol removal efficiency of 93.9%. • The sorption capacities of carbons were promoted by magnetic modification. [ABSTRACT FROM AUTHOR]

A novel optical waveguide LP 01 /LP 02 mode converter is proposed using combination of bicone structure based on the coupled-mode theory. It is composed of a cladding, a tapered core and combined bicone structure. It is found that this mode converter can have operating bandwidth of 1350–1700 nm, i.e. 350 nm, with a conversion efficiency of ∼ 90% ( ∼ 0.5 dB) and low crosstalk from other modes [ABSTRACT FROM AUTHOR]

This study assesses the feasibility of recycling drinking water treatment residue (DWTR) to treat eutrophic surface water in a one-year continuous flow column test. Heat-treated DWTR was used as an additional medium (2%–4%) in columns in case excessive organic matter and N were released from the DWTR to surface water. The results indicated that with minimal undesirable effects on other water properties, DWTR addition substantially enhanced P removal, rendering P concentrations in treated water oligotrophic and treated water unsuitable for Microcystis aeruginosa breeding. Long-term stable P removal by DWTR–column treatment was mainly attributed to the relatively low P levels in raw water (<0.108 mg L −1 ) and high P adsorption capability of DWTR, as confirmed by increases in amorphous Al/Fe in DWTR after the tests and low adsorption of P in the mobile forms. The major components of DWTR showed minimal changes, and potential metal pollution from DWTR was not a factor to consider during recycling. DWTR also enriched functional bacterial genera that benefitted biogeochemical cycles and multiple pollution control (e.g., Dechloromonas , Geobacter , Leucobacter , Nitrospira , Rhodoplanes, and Sulfuritalea ); an apparent decrease in Mycobacterium with potential pathogenicity was observed in DWTR–columns. Regardless, limited denitrification of DWTR–columns was observed as a result of low bioavailability of C in surface water. This finding indicates that DWTR can be used with other methods to ensure denitrification for enhanced treatment effects. Overall, the use of DWTR as an additional medium in column systems can potentially treat eutrophic surface water. [ABSTRACT FROM AUTHOR]

This study presents an approach for developing inactivating materials to achieve an initial rapid and a long-term equilibrium P immobilization to control eutrophication based on drinking water treatment residue (DWTR), which is a byproduct of potable water production. By taking advantage of the long-term equilibrium P adsorption by DWTR, the La chemical properties, and the previous success of using La-modified bentonite clay (Phoslock ® ), we used DWTR as a La carrier with different ratios to develop the specific materials. The La loading mechanisms, the potentially toxic effect of La-modified DWTR on snail Bellamya aeruginosa (within 120 d), and the short- and long-term (within 80 d) P immobilization characteristics of the modified DWTR were investigated to understand the performance of the developed materials. The results showed that La loading into DWTR was based on ligand exchanges and the formation of new particles; DWTR loaded with <5% La had no toxicity against the snail. Most importantly, the loading of 5% La to DWTR substantially enhanced the rapid immobilization capacity of DWTR, achieving an initial rapid and a long-term equilibrium P adsorption in aqueous solutions. This study promotes the beneficial recycling of DWTR and results in a win-win situation for lake restoration. [ABSTRACT FROM AUTHOR]

Recycling of drinking water treatment residuals (DWTRs) in aquatic environment remediation can provide numerous benefits. The hazardous effect of DWTR metals on the environment is shown to be limited; however, DWTR may release excessive nitrogen and organic matter, hindering recycling in the aquatic environment. To eliminate any potential unfavorable effect, self-purification via intermittent aeration incubation for DWTRs was developed. Results indicated that after approximately 5–6 months of incubation, the easily released nitrogen and organic matter in the DWTRs were mostly removed. The removed nitrogen was found to mainly consist of ammonium nitrogen from inorganic and organic nitrogen groups in the DWTRs. The removed organic matter consisted mainly of humic-like substances associated with the carboxyl group, distributed on the surface of the DWTRs. Biological mechanisms for effective nitrogen and organic matter removal were further explored based on the analysis of bacterial community structure, which indicated that the dominant bacteria genera (e.g., Geothrix , Methylotenera , and Geobacter ) in the DWTRs after incubation were closely related to nitrogen and carbon cycles. In addition, the phosphorus adsorption of the DWTRs after incubation was maintained, and the specific surface area, total pore volume, microporosity, and mesoporosity of the DWTRs after incubation tended to increase because of organic matter removal. Accordingly, intermittent aeration not only addressed the concerns caused by potential excessive release of nutrients from DWTRs but also enhanced the favorable effect of DWTRs on biogeochemical cycles. Self-purification can potentially promote the beneficial recycling of DWTRs in the aquatic environment. [ABSTRACT FROM AUTHOR]

Abstract: Nitrogen (N) ammonification and nitrification are two primary microbial processes controlling the availability of soil ammonium (NH4+), a key nutrient for vegetative growth. The large‐scale patterns of gross ammonification (GA) and gross nitrification (GN) rates represent soil microbial adaptations to different vegetative and environmental conditions. In this study, we investigated GA and GN rates in nine forest soils along a 3,700‐km north–south transect in eastern China. We used 15N‐labelling techniques, along with field experiments and laboratory incubations, to assess in situ and potential rates of the GA and GN. The mean in situ GA rate was 4.9 ± 0.5 mg N kg−1 day−1, whereas the mean potential rate of GA was 32.0 ± 8.6 mg N kg−1 day−1. The mean in situ GN rate was 1.7 ± 0.3 mg N kg−1 day−1 (potential GN rate: 3.2 ± 0.6 mg N kg−1 day−1). GA was significantly higher than GN along the transect, and there were high variations in GA and GN among different forests. Significant relationships were identified between meteorological factors (temperature and precipitation) and the GA and GN rates during the sampling month (August 2013). However, the mean GA rate in primary forest was significantly lower in the Huzhong (HZ), Dongling (DL), Taiyue (TY) and Dinghu (DH) sites compared with other sites, whereas with the exception of the Liangshui (LS) sampling site, the mean GN rate in primary and secondary forests showed the same trends. Significant differences in GA rates were found between primary and secondary forests at the LS and Changbai (CB) sites, and differences were detected in GN rate at the HZ, LS and Jiulian (JL) sites. Structural equation modelling analysis suggested that soil N contents, microbial biomass N pool sizes and bacterial abundance are the primary determinants of the in situ rates of GA and GN. The strong control of edaphic factors on GA and GN indicates a need to improve soil N models with more explicit representation of edaphic factors and their control on soil N transformations. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

A novel method for mass air flow (MAF) sensor bias compensation and error map (or look-up table) adaptation with model error correction is proposed. A key feature of the approach is its method of handling and storing operating-point-dependent MAF sensor errors due to installation and ageing in diesel engines; such errors lead to adverse impacts on emission performance. The model of the MAF sensor error depending on the engine operating point is represented as a two-dimensional (2D) map, which is described as a piecewise bilinear interpolation model in the form of a vector–vector dot product. The mean-value engine model of a diesel engine with additional model biases is analysed and employed to improve the estimation precision of the 2D map. Based on the combination of the 2D map regression model and diesel engine mean-value engine model with additional model biases, a linear parameter varying adaptive sliding mode observer is designed, which achieves the disturbance suppression for the nonlinear model errors, as well as the simultaneous estimation of the system state, linear model errors and map parameters. The convergence of the proposed algorithm is proven under the conditions of the persistent excitation and given inequalities. The observer is validated against simulation data from the engine software enDYNA provided by TESIS. The results demonstrate that the estimation precision of the MAF sensor error map can be improved using the proposed method. [ABSTRACT FROM AUTHOR]

Phosphorus (P) immobilization by inactivating agents in the sediment of eutrophic lakes to reduce immediately available P in lake water is often crucial for mitigating nuisance eutrophication symptoms, such as cyanobacterial blooms. Macrophytes and phytoplankton, however, can directly utilize P from the sediment for growth. Accordingly, a comprehensive analysis of the P bioavailability in lake sediment amended with two promising P-inactivation agents, namely Phoslock ® and drinking water treatment residue (DWTR), was investigated in both short- and long-term studies (20 and 180 d). Phosphorus-availability was assessed using six chemical extraction methods and Hydrilla verticillata and Microcystis aeruginosa growth tests. The results showed that Phoslock ® and DWTR significantly reduced mobile P (NH 4 Cl and Na 2 S 2 O 4 /NaHCO 3 extractable P) in lake sediment, while P bioavailability that was assessed by different methods showed considerable deviations. Interestingly, appropriate bioavailable P chemical extraction methods were determined based on linear correlation analysis, and further comparison indicated that reduction of bioavailable P by DWTR (<55% for macrophyte available P) and Phoslock ® (<17% for cyanobacteria available P) were clearly less than the mobile P immobilization (>75%) at recommended dosages, which was probably caused by the capability of macrophyte and cyanobacteria to utilize various fractions of P (except the residual P) in amended sediment under proper illumination. Therefore, DWTR and Phoslock ® can effectively reduce P release from lake sediment, but the potential bioavailable P may pose uncertainties for eutrophication control in lakes that typically have regular sediment re-suspension. Overall, an evaluation of the bioavailable P pool in the lake ecosystem should be essential for successful lake geo-engineering. [ABSTRACT FROM AUTHOR]

Soil net nitrogen (N) mineralization (Nmin) is a pivotal process in the global N cycle regulating the N availability of plant growth. Understanding the spatial patterns of Nmin, its temperature sensitivity ( Q10) and regulatory mechanisms is critical for improving the management of soil nutrients. In this study, we evaluated 379 peer-reviewed scientific papers to explore how Nmin and the Q10 of Nmin varied among different ecosystems and regions at the global scale. The results showed that Nmin varied significantly among different ecosystems with a global average of 2.41 mg N soil kg−1 day−1. Furthermore, Nmin significantly decreased with increasing latitude and altitude. The Q10 varied significantly among different ecosystems with a global average of 2.21, ranging from the highest found in forest soils (2.43) and the lowest found for grassland soils (1.67) and significantly increased with increasing latitude. Path analyses indicated that Nmin was primarily affected by the content of soil organic carbon (C), soil C:N ratio, and clay content, where Q10 was primarily influenced by the soil C:N ratio and soil pH. Furthermore, the activation energy ( Ea) of soil N mineralization was significantly and negative correlated with the substrate quality index among all ecosystems, indicating the applicability of the carbon quality temperature hypothesis to soil N mineralization at a global scale. These findings provided empirical evidence supporting that soil N availability, under global warming scenarios, is expected to increase stronger in colder regions as compared with that low-latitude regions due to the higher Q10. This may alleviate the restriction of N supply for increased primary productivity at higher latitudes. [ABSTRACT FROM AUTHOR]

The beneficial recycling of drinking water treatment residue (DWTR) for environmental remediation has attracted growing attention, and oxygen-limited heat treatment has a high potential to improve DWTR adsorptive properties for better recycling. In this study, physicochemical property variation induced by oxygen-limited heat treatment was evaluated for six DWTR obtained from different drinking water treatment plants in Australia, China, and Ireland. The results showed that the changes in many properties, typically amorphous Al and Fe contents, mesopores, specific surface area (SSA), and total pore volume (TPV) of DWTR after treatment, showed inconsistent trends. The treatment also led to the varied lability of metals and As in DWTR although the human bioaccessibility and plant bioavailability of most metals decreased. Accordingly, oxygen-limited heat treatment may not be applicable for all DWTR improvement. Based on these findings, pre-screening processes to evaluate adsorptive properties and metal and metalloid lability were determined. Oxygen-limited heat treatment was more applicable to DWTR with neutral and weak alkaline properties (pH 7.0–7.8), low humic acid (HA) content (<2.09 mg g −1 ), and high amorphous Fe and HA ratio (>5.93), as well as with relatively high amorphous Al and HA ratio and high humin content. [ABSTRACT FROM AUTHOR]

Drinking water treatment residue (DWTR) seems to be very promising for controlling lake sediment pollution. Logically, acquisition of the potential toxicity of DWTR will be beneficial for its applications. In this study, the toxicity of DWTR and sediments amended with DWTR to Aliivibrio fischeri was evaluated based on the Microtox ® solid and leachate phase assays, in combination with flow cytometry analyses and the kinetic luminescent bacteria test. The results showed that both solid particles and aqueous/organic extracts of DWTR exhibited no toxicity to the bacterial luminescence and growth. The solid particles of DWTR even promoted bacterial luminescence, possibly because DWTR particles could act as a microbial carrier and provide nutrients for bacteria growth. Bacterial toxicity (either luminescence or growth) was observed from the solid phase and aqueous/organic extracts of sediments with or without DWTR addition. Further analysis showed that the solid phase toxicity was determined to be related mainly to the fixation of bacteria to fine particles and/or organic matter, and all of the observed inhibition resulting from aqueous/organic extracts was identified as non-significant. Moreover, DWTR addition not only had no adverse effect on the aqueous/organic extract toxicity of the sediment but also reduced the solid phase toxicity of the sediment. Overall, in practical application, the solid particles, the water-soluble substances transferred to surface water or the organic substances in DWTR had no toxicity or any delayed effect on bacteria in lakes, and DWTR can therefore be considered as a non-hazardous material. [ABSTRACT FROM AUTHOR]

The carbon- and nitrogen-rich soils of montane grasslands are exposed to above-average warming and to altered precipitation patterns as a result of global change. To investigate the consequences of climatic change for soil nitrogen turnover, we translocated intact plant-soil mesocosms along an elevational gradient, resulting in an increase of the mean annual temperature by approx. 2 °C while decreasing precipitation from approx. 1500 to 1000 mm. Following three years of equilibration, we monitored the dynamics of gross nitrogen turnover and ammonia-oxidizing bacteria ( AOB) and archaea ( AOA) in soils over an entire year. Gross nitrogen turnover and gene levels of AOB and AOA showed pronounced seasonal dynamics. Both summer and winter periods equally contributed to cumulative annual N turnover. However, highest gross N turnover and abundance of ammonia oxidizers were observed in frozen soil of the climate change site, likely due to physical liberation of organic substrates and their rapid turnover in the unfrozen soil water film. This effect was not observed at the control site, where soil freezing did not occur due to a significant insulating snowpack. Climate change conditions accelerated gross nitrogen mineralization by 250% on average. Increased N mineralization significantly stimulated gross nitrification by AOB rather than by AOA. However, climate change impacts were restricted to the 2-6 cm topsoil and rarely occurred at 12-16 cm depth, where generally much lower N turnover was observed. Our study shows that significant mineralization pulses occur under changing climate, which is likely to result in soil organic matter losses with their associated negative impacts on key soil functions. We also show that N cycling processes in frozen soil can be hot moments for N turnover and thus are of paramount importance for understanding seasonal patterns, annual sum of N turnover and possible climate change feedbacks. [ABSTRACT FROM AUTHOR]

Drinking water treatment residuals (WTRs) have a potential to realize eutrophication control objectives by reducing the internal phosphorus (P) load of lake sediments. Information regarding the ecological risk of dewatered WTR reuse in aquatic environments is generally lacking, however. In this study, we analyzed the eco-toxicity of leachates from sediments with or without dewatered WTRs toward algae Chlorella vulgaris via algal growth inhibition testing with algal cell density, chlorophyll content, malondialdehyde content, antioxidant enzyme superoxide dismutase activity, and subcellular structure indices. The results suggested that leachates from sediments unanimously inhibited algal growth, with or without the addition of different WTR doses (10% or 50% of the sediment in dry weight) at different pH values (8–9), as well as from sediments treated for different durations (10 or 180 days). The inhibition was primarily the result of P deficiency in the leachates owing to WTR P adsorption, however, our results suggest that the dewatered WTRs were considered as a favorable potential material for internal P loading control in lake restoration projects, as it shows acceptably low risk toward aquatic plants. [ABSTRACT FROM AUTHOR]

Lake restoration (typically sediment dredging) commonly involves producing a new sediment-water interface (SWI). This study comprehensively investigated the migration and transformation of P during the formation of a new SWI under different dissolved oxygen (DO) levels in the overlying water, based on Fe/Al-rich sediment. The results suggest that DO had a profound effect on the 0–7 cm sediment layer properties and higher DO levels in the overlying water resulted in the diffusion of DO deeper into the sediments. Importantly, besides preventing Fe reductive dissolution and sulfides competition, higher DO levels inhibited the release of P from sediment by inducing the mitigation of P from the upper (0–3 cm) into the bottom (3–7 cm) sediments. The migration of P was found to be closely related to the interactions between organic matter and Al, Fe, and Ca in the sediment profile caused by higher DO levels in overlying water. Particularly, the decrease in organic matter in the upper sediments increased the mobility of Ca and promoted aging of Al and Fe, which increased the migration of the different forms of P. The increased organic matter in the bottom sediments retained the mobile Ca and increased amorphous Fe, which immobilized the P that had migrated from the upper sediments. These results demonstrate the relatively high mobility of P in the upper sediments and the importance of P immobilization capability of bottom sediments on regulating P release from SWI under higher DO levels in overlying water. Accordingly, measures for lake restoration with producing a new SWI were recommended to be applied in combination with P immobilization method to develop more feasible strategies. [Display omitted] • Higher dissolved oxygen levels induce P mitigation from upper to bottom sediments. • P mobility enhances by increased Al/Fe aging and Ca mobility at upper sediment. • The accumulated amorphous Fe and Ca promote P immobilization at bottom sediment. • Al, Fe, and Ca distributions are regulated by organic matter in sediment profile. [ABSTRACT FROM AUTHOR]

Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (> 150 d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed. [ABSTRACT FROM AUTHOR]

Thein situimmobilization technique is a typical method of geoengineering in lakes for eutrophication control. The method reduces internal phosphorus loading from sediments by dosing chemicals, which means that selecting appropriate chemicals are essential. Therefore, the authors present a comprehensive review of the current available knowledge of chemicals used for thein situtechnique. Chemicals are classified into nine categories, and the control effectiveness and stability of the chemicals as well as the physicochemical and ecological responses to the control are reviewed. The authors also address challenges of chemicals in practical application and offers recommendations for future research. [ABSTRACT FROM PUBLISHER]

The present work provides an alternative straight-forward process protocol to achieve a binder-free electrode material with optimal performance for the large scale fabrication and application in electrochemical energy storage. The conventional method for the preparation of electrodes, also called slurry-coating technique, suffers some difficulty in boosting the high performance and large-scale industrial fabrication of electrode materials. It becomes equally urgent to develop advanced electrode materials and to design superior electrode architectures. Here, we prepared a flexible binder-free electrode material by anchoring ethylene glycol (EG) intercalated cobalt and nickel layered double hydroxide nanosheets on Ni foam (E–Co–Ni LDH/Ni foam) via a facile effective vacuum freeze-drying technique, following a modified coprecipitation. By this way, the complex steps in the slurry-coating process were avoided and excessively aggregating of the E–Co–Ni LDH nanosheets was refrained from, which supply high accessible surface area and large number of micro/mesopores for electrochemical reaction. When directly used as a supercapacitor electrode, the E–Co–Ni LDH/Ni foam displayed a high specific capacitance of 774 F g −1 at the current density of 0.2 A g −1 with a unique cyclability at a high load mass of 3.27 mg cm −2 . [ABSTRACT FROM AUTHOR]

As a by-product generated increasingly during potable water production, drinking water treatment residue (DWTR) recycling for environmental remediation can lead to a win–win situation. In this study, oxygen-limited heat treatment was applied to DWTR, attempting to tune the properties of DWTR for better recycling. The results showed that after the treatment, N 2 sorption capacity of DWTR was enhanced significantly: the specific surface area (SSA) and total pore volume (TPV) increased from 72.7 to 148–184 m 2 g −1 and from 0.0746 to 0.189–0.201 cm 3 g −1 , respectively. The treatment also relatively increased the amorphous Al/Fe contents in DWTR although Al/Fe aging and transformation from hydroxides to oxides with high stability were observed. The retained organic matter (OM) was dominant in humin, with higher aromaticity and lower aliphaticity as the treatment temperature increased. Further analysis suggested that aromaticity increase induced higher SSA, the combined effect of OM aromaticity increase, OM loss (e.g. C in COO − ), and metal oxides formation resulted in larger TPV, OM inhibited Al/Fe aging, while Al/Fe oxides formation in turn enhanced OM aromaticity. Additionally, the maximum Hg adsorption capacity of DWTR treated at 200–400 °C (estimated by Langmuir model) increased from 53.5 to 69.9–147 mg g −1 , and the lability of heavy metals (e.g. Cu) in DWTR tended to decrease after treatment. The overall results demonstrated that oxygen-limited heat treatment sequestrated C, making DWTR be a more reliable adsorbent. [ABSTRACT FROM AUTHOR]

Aluminum and Fe-based drinking water treatment residuals (DWTRs) have shown a high potential for use by geoengineers in internal P loading control in lakes. In this study, aging of Al/Fe-based DWTRs in lake water under different pH and redox conditions associated with their P immobilization capability was investigated based on a 180-day incubation test. The results showed that the DWTRs before and after incubation under different conditions have similar structures, but their specific surface area and pore volume, especially mesopores with radius at 2.1–5.0 nm drastically decreased. The oxalate extractable Al contents changed little although a small amount of Al transformed from oxidizable to residual forms. The oxalate extractable Fe contents also decreased by a small amount, but the transformation from oxidizable to residual forms were remarkable, approximately by 14.6%. However, the DWTRs before and after incubation had similar P immobilization capabilities in solutions and lake sediments. Even the maximum P adsorption capacity estimated by the Langmuir model increased after incubation. Therefore, it was not necessary to give special attention to the impact of Al and Fe aging on the effectiveness of DWTRs for geoengineering in lakes. [ABSTRACT FROM AUTHOR]

Internal P pollution in lakes is being increasingly recognized as a dominant cause of eutrophication. Lake geo-engineering is a commonly used method to accelerate P deposition and control pollution. This study aimed to bridge the gap between the theory and practice of such geo-engineering methods based on a comprehensive investigation of sediment P reactivation using 171 samples from 64 lakes in China. Given the importance of pH on sediment P lability, sediment pH was hypothesized to structure the potential of the lake's internal P pollution. The results showed that the reactivation of sediment P tended to be promoted by lower Al, Fe, and Ca and higher loss of ignition (LOI) at different sediment pH; it was also promoted with increasing pH at sediment pH < 7 and with decreasing pH at sediment pH > 7. Notably, the key properties, besides total P, affecting the release of soluble P from sediments under anoxic conditions were pH at sediment pH > 7 and Fe content at sediment pH < 7. The factors affecting the potential sediment P pool available for Microcystis aeruginosa were LOI and pH at sediment pH > 7 and LOI, pH, Fe, and Ca at sediment pH < 7. These results verified our hypothesis and suggested that the mechanisms affecting bioavailable P pollution were more complex compared to those of soluble P. The sediment pH effect was further verified owing to the varied coupling of sediment properties with P distributions at different pH. Therefore, the sediment pH effect on the potential of internal P pollution should be taken into full consideration to design appropriate geo-engineering methods for lake restoration. [Display omitted] • Sediment P reactivation mechanism was studied based on 171 samples from 64 lakes. • Key sediment properties affecting P re-activation varied at different sediment pH. • Sediment mobile P and bioavailable P had different key affecting properties. • Sediment pH could be the fundamental data to develop lake geo-engineering. Accordingly, higher Al, Fe, Ca, and pH, as well as lower LOI and TP reduced the release of soluble P and the potential of M. aeruginosa to utilize P from sediments at pH > 7. Similar trends were observed in sediments at pH < 7, except that higher pH was favorable for P reactivation in sediments with pH < 7. Based on the best correlations determined here, the key properties (besides TP) affecting the soluble P release were pH at sediment pH > 7 and Fe at sediment pH < 7; those affecting the available P pool in sediment for M. aeruginosa were LOI and pH at sediment pH > 7 and LOI, pH, Fe, and Ca at sediment pH < 7. [ABSTRACT FROM AUTHOR]

Great efforts have long been made to control sediment pollution from persistent organic pollutants and phosphorus for aquatic ecosystem restoration. This study proposed a novel recycling of drinking water treatment residue (DWTR) to synchronously control sediment polycyclic aromatic hydrocarbons (PAHs) and phosphorus pollution based on a 350-day incubation test. The results suggested that DWTR addition reduced approximately 88%− 96% of potential bioavailable PAHs and 76% of mobile phosphorus in sediment. The dominant mechanisms for both reductions by DWTR were immobilization, mainly through increasing sediment amorphous aluminum and iron. The tendency of enhanced PAHs degradation by DWTR was also observed, especially for high molecular weight PAHs (e.g., chrysene, indeno(1, 2, 3-cd)pyrene, and benzo(g, hi)perylene), which decreased by approximately 21.1%− 22.0% of the total. Additionally, accompanying a clear increase in the connections of microbial cooccurrence networks, the variations in bioavailable PAHs, amorphous aluminum and iron, and other properties (e.g., pH, nitrogen, and organic matter) significantly (p < 0.01) enhanced Flavobacterium enrichment, although the enrichment of many other microbes potentially related to PAHs degradation (e.g., C1-B045) decreased after DWTR addition. Therefore, DWTR could promote the construction of a "PAHs immobilization with microbial augmentation" system while immobilizing phosphorus in sediment, indicating the high feasibility of controlling multiple sediment pollution. [Display omitted] • Drinking water treatment residue (DWTR) synchronously reduced PAHs and P pollution. • Dominant mechanism for both reductions was immobilization by amorphous Al and Fe. • DWTR induced to build a microbial augmentation system to degrade PAHs in sediment. • DWTR affected microbial effect by changing pH, PAHs, P, N, Al, Fe, and organics. [ABSTRACT FROM AUTHOR]

In this work, the labilities of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in air-dried (for 60 days) and fresh dewatered WTRs were compared using the Toxicity Characteristic Leaching Procedure (TCLP), fractionation,in vitrodigestion and a plant enrichment test. The results showed that the air-dried and fresh dewatered WTRs had different properties, e.g., organic matter composition and available nutrients. The air-dried and fresh dewatered WTRs were non-haf zardous according to the TCLP assessment method used in the United States; however, the metals in the two types of WTRs had different lability. Compared with the metals in the fresh dewatered WTRs, those in the air-dried WTRs tended to be in more stable fractions and also exhibited lower bioaccessibility and bioavailability. Therefore, air-drying can decrease the metal lability and thereby reduce the potential metal pollution risk of WTRs. [ABSTRACT FROM AUTHOR]

Nitrification is a central component of the terrestrial nitrogen (N) cycle, but the contribution of autotrophic and heterotrophic nitrification to total gross nitrification remains poorly understood. To clarify their relative importance in neutral and moderate acid soils, an incubation experiment was conducted with 15 N-ammonium isotopic pool dilution techniques and combined with acetylene (C 2 H 2 , 10 Pa) as a specific inhibitor of autotrophic nitrification and sodium chlorate (NaClO 3 ) as a potential inhibitor of heterotrophic nitrification. Additionally, CO 2 , N 2 O and CH 4 fluxes were measured to identify potential side-effects of inhibitors on soil respiration and CH 4 fluxes. The presence of C 2 H 2 completely eliminated gross nitrification in all investigated soil samples. The addition of NaClO 3 affected neither gross nitrification nor gross ammonification in soils of both investigated grassland sites. This provided strong evidence that heterotrophic nitrification was not an important process in the investigated grassland soils. Acetylene but not NaClO 3 decreased net CH 4 uptake, likely due to homology of the enzymes ammonia monooxygenase. Overall, the present study shows a dominant role of autotrophic nitrification in gross nitrate production for both neutral and slightly acid soils and illustrates the potential of acetylene as an inhibitor of gross autotrophic nitrification. [ABSTRACT FROM AUTHOR]

• Resuspension-induced material redistribution varied sediment P immobilization. • Surface sediment P immobilization was lower than that in bottom sediment. • Redistribution of potential target P was typically regulated by < 8 μm sediment. • Redistribution of material was typically regulated by > 63 μm particles. Lake geoengineering with phosphorus (P)-inactivating materials to reduce sediment P loading is often used for eutrophication control. The redistribution of materials in sediment, especially those induced by resuspension, is reportedly a common phenomenon during practical applications, which may interfere with the pollution control. Notably, a recent study by the authors initially found that the heterogeneous properties of materials and sediments varied the P immobilization in different sized sediments which exhibited diverse movement characteristics. Therefore, this study hypothesizes a particle size-related vertical redistribution of materials in the sediment profile induced by resuspension, which shapes sediment P immobilization at different depths. Based on two differently sized materials, lanthanum (La)-modified bentonite clay (Phoslock) and drinking water treatment residue (DWTR), this study found a weakened reduction of mobile P and bioavailable P pool by both DWTR and Phoslock in surface sediment after resuspension. As the depth decreased from >12 to surface 0–1 cm, the remaining mobile P increased from 7.11%–10.8% to 11.0%–17.8% of the total P in the sediment with Phoslock and from 1.66%–4.73% to 9.70%–20.7% of the total P in the sediment with DWTR; meanwhile, bioavailable P pool reduction proportions decreased from 48.6%–72.3% to 3.23%–45.1% for Phoslock and from 51.5%–71.4% to 4.94%–25.2% for DWTR. Further analysis verified the hypothesis of this study; importantly, the redistributions of the potential target P (including mobile and bioavailable P) for immobilization were regulated by relatively small sediments (e.g., <8 μm fraction), which tended to become enriched in surface sediment after resuspension, while relatively large materials (e.g., >63 μm fraction) regulated their redistributions and were more likely to be buried at the bottom of the sediments. Accordingly, to design appropriate strategies for lake geoengineering, relatively small materials (e.g., <8 μm) targeting to immobilize both mobile and bioavailable P are typically recommended to be developed for restoration of lakes with frequent sediment resuspension. [Display omitted] [ABSTRACT FROM AUTHOR]

As an inevitable by-product of potable water production, drinking water treatment residue (DWTR) recycling to make ceramsite can provide both environmental and economic benefits in constructing filtration treatment system for water environment remediation. Given the varied properties of DWTR from different waterworks, this study aims to identify the key factors affecting ceramsite production from DWTR as main ingredient based on five different DWTR with using clay as the auxiliary material. The results showed that of sintering temperature (500–1000 °C), DWTR:clay ratio (5:5 to 9:1), sintering time (5–60 min), and granule diameter (5–15 mm), the sintering temperature was the key parameter. Increasing temperatures from 500 to 1000 °C gradually promoted DWTR sintering by enhancing Si and Al crystallization, which typically increased the formation of SiO 2 and CaAl 2 Si 2 O 8 crystals in ceramsite. Ceramsites made from different DWTR tended to have different properties, mainly resulting from varied contents of Si (20.2%–48.6%), K (0.0894%–2.39%), Fe (4.56%–14.3%), and loss on ignition (11.7%–39.5%). During ingredients preparation to produce up-to-standard ceramsite, supplying additional Si and diluting loss on ignition were necessary for all DWTR, while supplying K and diluting Fe may be required for specific DWTR, due to the potential varied DWTR compositions caused by different water production processes applied (e.g., type of flocculants). Further toxicity characteristic leaching procedure analysis indicated the increased leaching of Cu. However, DWTR based ceramsite was identified as non-hazardous material; even, sintering treatment reduced the leachability of Ba, Be, Cd, and Cr. DWTR based ceramsite also had relatively high specific surface area (22.1–50.5 m2/g) and could adsorb Cd, Cu, and Pb from solution. Overall, based on appropriate management, DWTR can be recycled as the main ingredient in the production of ceramsite for water environment remediation. [Display omitted] • Factors affecting ceramsite made from water treatment residue (DWTR) were studied. • Higher sintering temperature promoted SiO 2 /CaAl 2 Si 2 O 8 producing to make ceramiste. • Varied Si, K, Fe, and loss on ignition (LOI) of DWTR regulated ceramsite property. • Supplying Si and diluting LOI to DWTR was necessary for ingredients preparation. • DWTR based ceramiste was non-hazardous and feasible to adsorb Cd, Cu, and Pb. [ABSTRACT FROM AUTHOR]

Miniaturized micro‐spectrometers with high‐resolution and large‐bandwidth are of great importance for on‐site spectroscopic analysis applications. Here, a novel high‐resolution and large‐bandwidth micro‐spectrometer is presented, which operates at dual‐wavelength band by utilizing a (N + 3) × (N + 3) arrayed waveguide grating (AWG) and three dual‐wavelength grating couplers on a silicon‐on‐insulator (SOI) platform. The AWG working in a counter‐propagating manner can be viewed as two 3 × N AWGs, and the dual‐wavelength grating coupler acts as a prefilter. Three time‐division‐multiplexing inputs with wavelength spacings of 4/3 times that of N output waveguides are employed to improve the resolution of the micro‐spectrometer. Combining the corresponding outputs of three inputs, a micro‐spectrometer with resolution enhanced to one‐third wavelength spacing of output waveguides and effective channel number enlarged to 3 × (N − 2) is achieved, only using N output channels at each wavelength band. A micro‐spectrometer with 63 effective channels and resolutions of 0.5 and 0.442 nm at 1550 and 1310 nm bands, respectively, is experimentally demonstrated. The footprint of the fabricated micro‐spectrometer is 2 × 0.81 mm2, with measured on‐chip losses of −4.6 to −2.8 dB (−7.0 to −3.1 dB) and crosstalk levels < −18.5 (−16.8) dB at the 1550 (1310) nm band. [ABSTRACT FROM AUTHOR]

Highlights: [•] The lability of 18 metals in WTR was studied using an anaerobic incubation test. [•] Most metals in WTR were stable. [•] Certain metals (e.g., Mn) lability in WTR increased substantially. [•] Metal lability in WTRs was recommended to be determined before application. [ABSTRACT FROM AUTHOR]

Abstract: Drinking water treatment residuals (WTRs), non-hazardous by-products generated during potable water production, can effectively reduce the lake internal phosphorus (P) loading and improve water quality in lakes. It stands to reason that special attention regarding the beneficial reuse of WTRs should be given not only to the effectiveness of P pollution control, but also to the effects on the migration and transformation of other nutrients (e.g., nitrogen (N)). In this work, based on laboratory enrichment tests, the effects of WTRs addition on nitrification in lake sediment were investigated using batch tests, fluorescence in situ hybridization, quantitative polymerase chain reaction and phylogenetic analysis techniques. The results indicated that WTRs addition had minor effects on the morphologies of AOB and NOB; however, the addition slightly enhanced the sediment nitrification potential from 12.8 to 13.2 μg-N g−1-dry sample h−1 and also increased the ammonia oxidation bacteria (AOB) and nitrite oxidizing bacteria (NOB) abundances, particularly the AOB abundances (P < 0.05), which increased from 1.11 × 108 to 1.31 × 108 copies g−1-dry sample. Moreover, WTRs addition was beneficial to the enrichment of Nitrosomonas and Nitrosospira multiformis and promoted the emergence of a new Nitrospira cluster, causing the increase in AOB and NOB diversities. Further analysis showed that the variations of nitrification in lake sediment after WTRs addition were primarily due to the decrease of bioavailable P, the introduction of new nitrifiers and the increase of favorable carriers for microorganism attachment in sediments. Overall, these results suggested that WTRs reuse for the control of lake internal P loading would also lead to conditions that are beneficial to nitrification. [Copyright &y& Elsevier]

Highlights: [•] The dosage of WTRs required to immobilize mobile P in sediments was investigated. [•] The P immobilization capacity of WTRs can be expressed as an equation. [•] Most of mobile P in sediments can be immobilized by WTRs at determined dosages. [ABSTRACT FROM AUTHOR]

Highlights: [•] WTRs had low metals leaching risk in lake water. [•] The P adsorption capacity of the raw and settled WTRs had little difference. [•] The raw and settled WTRs had the same ability to immobilize P in lake sediments. [ABSTRACT FROM AUTHOR]

Highlights: [•] WTRs promoted the aggregation of anammox bacteria in lake sediments. [•] WTRs strengthened the activity of anammox bacteria in lake sediments. [•] WTRs increased the abundance of anammox bacteria in lake sediments. [•] WTRs caused anammox bacteria to be more closely related to Candidatus Brocadia. [ABSTRACT FROM AUTHOR]

The classical lake internal phosphorus (P) pollution control using P-inactivating materials is typically carried out by reducing the release of soluble P from sediments to overlying water; however, particulate P loading through sediment resuspension could also cause internal P pollution for algae breeding. Therefore, based on lanthanum modified bentonite clay (Phoslock®) and drinking water treatment residues (DWTR), the effect of P inactivating materials on sediment resuspension and settlement were comprehensively investigated to assess the variations in particulate P pollution from sediment. Results showed that both materials could effectively control soluble P pollution from sediment, while both had limited effect on the supplement of particulate P to overlying water. The reason may be that hydrodynamic disturbance was the key factor regulating sediment resuspension and settlement. The disturbance induced the resuspension of different sized sediments, especially <8 μm fractions, while increasing disturbing intensities promoted resuspension of relatively larger sized sediments (e.g., <63 μm). Further analysis suggested that after resuspension and settlement, the efficiencies of reducing bioavailable P by Phoslock® in relatively large sized sediment fraction (e.g., <63 μm) were substantially less than those in relatively small sized sediment (<8 μm). Although the reducing efficacies of DWTR had limited changes in different sized sediments, the remaining bioavailable P were clearly higher in smaller sized sediments with DWTR. The different performances on bioavailable P reduction mainly resulted from the distributions of materials and original P in different sized sediments. These findings indicated the potential supplement of particulate P for algal growth during resuspension and settlement of sediments amended by P inactivating materials. Overall, understanding the sediment P bioavailability and hydraulic properties at different sizes and the lake hydrodynamic conditions is essential to develop appropriate methods to control lake internal P pollution. • Phoslock® and water treatment residue had limited effect on particulate-P loading. • Phoslock® is more feasible to reduce bioavalible P in <8 μm fraction of sediment. • The residue to reduce bioavalible P in different sized sediments was similar. • Sediment particulate-P required more attention for lake eutrophication control. [ABSTRACT FROM AUTHOR]

Abstract: The reuse of drinking water treatment residuals (WTRs) to immobilize phosphorus (P) in sediments is a novel application for lake restoration. The recycling of WTRs is beneficial from both environmental and economic standpoints. This work assessed the stability of P in sediments found in Lake Taihu and Lake Baiyangdian before and after being amended with WTRs. The results indicated that WTRs had similar effects on the stability of P in each of the lake's sediments. WTRs can significantly reduce the P desorption potential of the sediments at pH values less than 11. WTRs can also inhibit the competitive adsorption of SiO4 2− with P. Compared with the raw sediments, the organic matter in the sediments, ion strength and anaerobic conditions presented minor undesirable effects on the stability of P in the WTRs-amended sediments. Moreover, WTRs can increase the P adsorption rate and capacity of the sediments. Overall, these results demonstrated that WTRs can make P more stable in lake sediments under various conditions. [Copyright &y& Elsevier]

Highlights: [•] Water treatment residuals (WTRs) reduced internal P loading from lake sediments. [•] The retained-P by WTRs was stable in lake sediments. [•] WTRs presented minimum changes to the surroundings. [Copyright &y& Elsevier]

Abstract: The use of drinking water treatment residuals (WTRs) to immobilize P in sediments is a novel approach for lake restoration. However, the lability of P in WTRs-amended sediments may vary with many factors, e.g., hydrogen sulfide content. Earlier works in our laboratory have demonstrated that WTRs are effective sorbents for hydrogen sulfide in water. Thus, we hypothesized that the lability of P in WTRs-amended sediments would not be increased by hydrogen sulfide. The results of this work suggested that this hypothesis was tenable. Compared to the raw sediments, the amended sediments had significantly lower P desorption potential in the presence of hydrogen sulfide at different times, pH and concentrations. Moreover, the amended sediments were also better able to adsorb hydrogen sulfide. In the amended sediments, the P, which was easily desorbed due to the effect of hydrogen sulfide, was transformed into the Fe/Al bound P. [Copyright &y& Elsevier]

Abstract: In this work, the remediation of soils contaminated with multiple metals using ferric and alum water treatment residuals (FARs) in Baiyin, China, was investigated. The results of metals fractionation indicated that after the soil was treated with FARs, arsenic (As), lead (Pb), nickel (Ni), zinc (Zn) and copper (Cu) could be transformed into more stable forms, i.e., As bound in crystalline Fe/Al oxides and other metals in the oxidable and residual forms. However, the forms of chromium (Cr) and cadmium (Cd) were unaffected. Interestingly, due to the effect of FARs, barium (Ba) was predominantly transformed into more mobile forms. The bioaccessibility extraction test demonstrated that the FARs reduced the bioaccessibility of As by 25%, followed by Cu, Cr, Zn, Ni and Pb. The bioaccessibility of Cd and Ba were increased; in particular, there was an increase of 41% for Ba at the end of the test. In conclusion, the FARs can be used to remedy soil contaminated with multiple metals, but comprehensive studies are needed before practical applications of this work. [Copyright &y& Elsevier]

Abstract: This work investigated the potential for reusing water treatment residuals (WTRs) to immobilize phosphorus (P) in the sediments of Lake Taihu and Lake Baiyangdian. The results indicated that WTRs made inorganic P more stable in the sediments, although the sediments from each lake had dissimilar properties. Conversely, WTRs had no effect on the activity of organic P. However, after the sediment was mixed with WTRs, the inorganic P was immobilized in 10days. Microbiological analyses further revealed that WTRs could alter the structures of the microbial community within the sediments but exert no adverse effect on the bacterial diversity. Moreover, WTRs were found to be beneficial to microorganism growth. Because of the effects exerted by WTRs, the total abundance of bacteria in the sediments increased from 5.10×1012 to (0.66–4.81)×1014 copies g−1 for Lake Baiyangdian sediments and from 1.16×1013 to (1.08–7.14)×1014 for Lake Taihu sediments. Therefore, WTRs can be safely used to immobilize P in sediments for the purpose of lake restoration. [Copyright &y& Elsevier]

Abstract: This work investigated the characteristics and mechanisms of hydrogen sulfide adsorption by ferric and alum water treatment residuals (FARs) in solution. The results indicated that FARs had a high hydrogen sulfide adsorption capacity. pH 7 rather than higher pH (e.g. pH 8–10) was favorable for hydrogen sulfide removal. The Yan model fitted the breakthrough curves better than the Thomas model under varied pH values and concentrations. The Brunauer–Emmett–Teller surface area and the total pore volume of the FARs decreased after the adsorption of hydrogen sulfide. In particular, the volume of pores with a radius of 3–5nm decreased, while the volume of pores with a radius of 2nm increased. Therefore, it was inferred that new adsorption sites were generated during the adsorption process. The pH of the FARs increased greatly after adsorption. Moreover, differential scanning calorimetry analysis indicated that elemental sulfur was present in the FARs, while the derivative thermal gravimetry curves indicated the presence of sulfuric acid and sulfurous acid. These results indicated that both oxidization and ligand exchange contribute to the removal of hydrogen sulfide by FARs. Under anaerobic conditions, the maximum amount of hydrogen sulfide released was approximately 0.026mgg−1, which was less than 0.19% of the total amount adsorbed by the FARs. The hydrogen sulfide that was released may be re-adsorbed by the FARs and transformed into more stable mineral forms. Therefore, FARs are an excellent adsorbent for hydrogen sulfide. [Copyright &y& Elsevier]

Abstract: Nanostructured NiCo2O4 spinel was fabricated with a facile, low-cost coprecipitation process. The ethylene glycol was applied to serve as a stabilizer to govern over the nucleation, growth, and agglomeration processes. The influence of the calcination time was also studied on the coprecipitation reaction. Both the reaction conditions have statistically significant effects on the size distribution, crystallinity, electronic conductivity and the electrochemical performances of the products. The optimized, 5–10nm NiCo2O4 spinel, calcinated at 375°C for 8h, had excellent crystallinity and electric conductivity. It showed a superior-specific capacitance of 671Fg−1 at a current density of 1Ag−1. The delay in the specific capacitance was insignificant, after a 7000-cycle test, revealing the high stability of the product. The simplicity and practicability of the modified coprecipitation process may facilitate the successful commercial applications in electrochemical capacitors for nanostructured NiCo2O4 spinel. [Copyright &y& Elsevier]