Wastewater treatment performance and microbial community structure in the constructed wetland under double-pressure of low temperature and Ag NPs exposure

To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical flow constructed wetland was set up to treat synthetic wastewater under laboratory conditions.By measuring the effluent concentration of ammonia nitrogen(NH_(4)^(+)-N),total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),and the diversity,richness,and community structure of microorganisms of the upper and lower soil layers in the wetland,the nutrient removal effect of the constructed wetland and the changes in the microflora of the soil layer were studied.The results reveal that the correlation coefficients between the removal rates of TN and NH_(4)^(+)-N and the temperature are 0.463 and 0.692,respectively,indicating a significant positive correlation.From the warm to the cold season,both the diversity and richness of microorganisms in the lower soil layer of wetlands are inhibited under the double-pressure of Ag NPs and low temperature,and the abundances of the denitrogenation functional bacteria such as Candidatus nitrososphaera,Sulfuritalea,Anaeromyxobacter,Candidatus solibacter,Nitrospira,and Zoogloea are altered.Low temperature and Ag NPs exposure can thus affect the wastewater treatment performance of constructed wetlands,possibly because of the seasonal changes of the microflora.

Pilot study on treatment of low turbidity and low temperature water by coagulation-immersed membrane process

The objective of this paper was to investigate the practicability of coagulation-immersed membrane process during low-temperature period through the study of steady operation,chemical cleaning methods,water quality and agent consumption.Experimental results showed that:membrane performance decreases with the reduction of temperature,but low temperature has little effect on stable operation of immersed membrane when coagulation as pretreatment.EFM with 1200 mg/L sodium hypochlorite after every 48 filtration cycles was made for reducing membrane fouling efficiently,and the method,with 1.5% sodium hydroxide and 3500 mg/L sodium hypochlorite for 10 h and then 2% hydrochloric acid for 4 h,is an appropriate cleaning method under low temperature.Compared with convention treatment process,immersed membrane process not only has same agent consumption,but also permeated water quality is more superior such as fine removal effect on turbidity with average 0.10 NTU.Therefore,coagulation-immersed membrane process is more appropriate for increasing water quality demand and the treatment of low turbidity and low temperature water.

Form and Mechanism of Sulfate Attack on Cement-based Material Made of Limestone Powder at Low Water-binder Ratio under Low Temperature Conditions

The development of strength and the form of attack of cement-based material made of limestone powder at low water-binder ratio under low-temperature sulfate environment were studied. The results indicate that when water-binder ratio is lower than 0.40, the cement-based material with limestone powder has insignificant change in appearance after being soaked in 10% magnesium sulfate solution at low temperature for 120 d, and has significant change in appearance after being soaked at the age of 200 d. Expansion damage and exfoliation occur on the surface of concrete test cube at different levels. When limestone powder accounts for about 28 percent of cementitious material, with the decrease of water-binder ratio, the compressive strength loss has gradually decreased after the material is soaked in the magnesium sulfate solution at low temperature at the age of 200 d. After the specimen with the water-binder ratio of less than 0.4 and the limestone powder volume of greater than 20% is soaked in 10% magnesium sulfate solution at low temperature at the age of 200 d, gypsum attack-led destruction is caused to the concrete test cube, without thaumasite sulfate attack.

Distribution Characteristics of Winter Continuous Extreme Low Temperature in China

[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 observatories, the continuous extreme low temperature event (cold night) which happened in winter in China and the distribution characteristics of accumulated temperature anomaly in 48 years were analyzed by using the actual probability distribution threshold method. [Result] Besides in Northeast China, Northwest China and Qinghai-Tibet Plateau where the geographical position was northerly, and the altitude was high, the long-time (above 5 d) extreme low temperature event was also easy to happen in the south of Yangtze River, especially in Guizhou, Guangxi, Hunan and so on. The continuous extreme low temperature event in the middle and lower reaches of Yellow River was the least. Started from the metaphase of the 1980s, the frequency trend of continuous extreme low temperature event decreased. But in 1992, 2000 and 2007, the low temperature event which continued above 7 d was more than the average. The accumulated cold in January in 48 years was the strongest. The second one was in February, and the smallest was in December. The accumulated cold in Northeast China and the north of Inner Mongolia was the biggest in December and January. The accumulated cold in the north of Xinjiang was the biggest in February. In the whole winter, the accumulated cold in Qinghai-Tibet Plateau was the smallest. The chilling injury was easier to happen in Guizhou, Guangxi and Hunan than other south areas in December and February. The occurrence probability of chilling injury in most areas of Szechwan Basin, Yunnan and Qinling Mountains in central China was smaller than that in other areas. [Conclusion] The research provided the reference basis for analyzing the influence of chilling injury on the agriculture in China.

Reduction of Precursors of Chlorination By-products in Drinking Water Using Fluidized-bed Biofilm Reactor at Low Temperature

Objective To investigate the reduction of chlorination by-products （CBPs） precursors using the fluidized-bed biofdm reactor （FBBR）. Methods Reduction of total organic carbon （TOC）, ultraviolet absorbance （UV254）, tfihalomethane （THM） formation potential （THMFP）, haloacetic acid （HAA） formation potential （HAAFP）, and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3℃, however, it could quickly rise to over 50% above 3℃. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

Effects of Low Temperature-tolerant Microbial Inoculants from Municipal Solid Waste Compost on Turf Storage in Winter

Beneficial microorganisms were extracted from municipal solid waste compost and treated under low temperature stress to prepare complex microbial inoc- ulants. Turfgrass was inoculated with the prepared microbial inoculants to investigate the ecological effect of ~crobial inoculants on turf storage in winter. The re- suits showed that complex low temperature tolerant microbial inoculants significandy improved plant height and aboveground biomass of turfgrass. Compared with the non-inoculated control, plant height and biomass of the first batch of inoculated turfgrass were enhanced by 6.47% and 14.32%, respectively; and they were en- hanced by 6.94% and 17.41%, respectively, for the second batch of inoculated turfgrass. Under low temperature stress in winter, the reviving rate of inoculated tarfgrass was significandy higher than that of control, which was improved by 3.34% and 43.33% for the first and second batches of inoculated turfgrass respective- ly. After low temperature storage in winter, inoculated turfgrass revived in advance; specifically, the reviving date of the second batch of inoculated turfgrass was 3 d earlier than that of control. This low temperature tolerant microbial consortium was effective for turfgrass as an ecofriendly and acceptable technology to improve plant performance and development in winter and accelerate time to market of turf.

Effects of water application uniformity using a center pivot on winter wheat yield, water and nitrogen use efficiency in the North China Plain

In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP). The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) have become a research hotspot. In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers (the R3000 sprinklers were installed in the first span, the corresponding treatment was RS;the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85A impact sprinkler as the end gun (the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE. The results showed that the water application uniformity coefficients of R3000, D3000 and P85A along the radial direction of the pivot (CUH) were 87.5, 79.5 and 65%, respectively. While the uniformity coefficients along the traveling direction of the pivot (CUC) were all higher than 85%. The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant (P>0.05);however, the average grain yield of EG was significantly lower (P<0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively. The coefficients of variation (CV) of the grain yield had a negative correlation with the uniformity coefficient. The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments. The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons. Although the CUH of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE. However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers. Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP.

Proposal of a Solar Thermal Power Plant at Low Temperature Using Solar Thermal Collectors

To this day, only two types of solar power plants have been proposed and built: high temperature thermal solar one and photovoltaic one. It is here proposed a new type of solar thermal plant using glass-top flat surface solar collectors, so working at low temperature (i.e., below 100°C). This power plant is aimed at warm countries, i.e., the ones mainly located between -40° and 40° latitude, having available space along their coast. This land based plant, to install on the seashore, is technologically similar to the one used for OTEC (Ocean Thermal Energy Conversion). This plant, apart from supplying electricity with a much better thermodynamic efficiency than OTEC plants, has the main advantage of providing desalinated water for drinking and irrigation. This plant is designed to generate electricity (and desalinated water) night and day and all year round, by means of hot water storage, with just a variation of the power delivered depending on the season.

Behavioral Pattern of Native Food Isolates of <i>Yersinia</i><i>enterocolitica</i>and <i>Yersinia</i><i>intermedia</i>under Simulated Time-Temperature Combinations of the Food Chain

The public health significance of Yersinia spp. gives a new dimension to the prevailing food chain, wherein the foods do get exposed to heat and cold treatments. In this study, the effect of heat treatment on the native isolates of Yersinia enterocolitica CFR 2301 and Y. intermedia CFR 2303 revealed the D-values ranging from the lowest of 0.08 min at 65℃ in skim milk/beef gravy to the highest of 18.52 min at 50℃ in beef gravy. The heat sensitivity of both these cultures was in the order of Milli-Q water > 0.85% saline > skim milk > beef gravy. The z-values of the test cultures ranged from 7.55℃ for Y. intermedia to 12.08℃ for Y. enterocolitica. The heat sensitivity in Y. enterocolitica appeared to be related with growth incubation temperatures and also fatty acid profile of cell membrane. The effect of low temperature treatments (–20 ℃, 0℃ and 4℃ for 20 d) in water, saline and skim milk revealed the ability of Y. enterocolitica to survive more efficiently at –20℃, while Y. intermedia was more tolerant at 0℃. In packaged drinking water, Y. enterocolitica could survive and grow at 4℃ and 16℃, while at 30℃, inactivation was rapid. The findings did indicate that heat and cold treatments would not always ensure safety from Y. enterocolitica and Y. intermedia in the food chain.

Water deficit and cold stress on the evening primrose seed quality

Evening primrose is a valuable oilseed crop with pharmaceutical and nutritional supplementation. Due to presence of valuable and rare gamma linolenic fatty acid, research on this plant has been started since 1970s by German and Britain scientists. Information about evening primrose cultivation is going to rise. Following to pervious studies the goal of this experiment was to clarify the effect of water and temperature stresses on seed yield and seed quality. Results showed that seed yield was significantly influenced by low temperature and water deficit. Plants grown under cold stress during rosette stage produced a lower seed yield than controls. The lowest seed yield was observed in the plants grown under permanent stress. Although the oil content of seeds was not influenced by low temperature stress, water stress strongly influenced the oil content and water stress stimulates oil accumulation. Like oil content, the GLA production seems to be increased under water stress conditions.

A coupled cryogenic thermo-hydro-mechanical model for frozen medium:Theory and implementation in FDEM

This paper presents the development of a coupled modeling approach to simulate cryogenic thermo-hydro-mechanical(THM)processes associated with a freezing medium,which is then implemented in the combined finite-discrete element method code(FDEM)for multi-physics simulation.The governing equations are deduced based on energy and mass conservation,and static equilibrium equations,considering water/ice phase change,where the strong couplings between multi-fields are supplemented by critical coupling parameters(e.g.unfrozen water content,permeability,and thermal conductivity).The proposed model is validated against laboratory and field experiments.Results show that the cryogenic THM model can well predict the evolution of strongly coupled processes observed in frozen media(e.g.heat transfer,water migration,and frost heave deformation),while also capturing,as emergent properties of the model,important phenomena(e.g.latent heat,cryogenic suction,ice expansion and distinct three-zone distribution)caused by water/ice phase change at laboratory and field scales,which are difficult to be all revealed by existing THM models.The novel modeling framework presents a gateway to further understanding and predicting the multi-physical coupling behavior of frozen media in cold regions.

Low temperature hydrogen production from water and methanol over Pt/α-MoC catalysts

Subject Code:B03 With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Ma Ding(马丁)from Peking University,Prof.Zhou Wu(周武)from the University of Chinese Academy of Sciences,Prof.Wen Xiaodong(温晓东)from the Institute of

SO_2 poisoning and regeneration of Mn-Ce/TiO_2 catalyst for low temperature NO_x reduction with NH_3

SO2 poisoning and regeneration of Mn-Ce/TiO2 catalyst prepared by a novel co-precipitation method for low temperature selective catalytic reduction （SCR） of NOx with ammonia were investigated in this study. When 700 ppm SO2 was fed in, the Mn-Ce/TiO2 catalyst had good resistance to SO2, but the deactivation of Mn-Ce/TiO2 poisoned by SO2 still occurred. The NO conversion of Mn-Ce/TiO2 （the molar ra-tio of Ce to Ti is 0.075） catalyst decreased from 92.5% to 34.6% in 13 h. Characterizations of fresh and SO2-poisoned Mn-Ce/TiO2 catalysts were carried out by Brunauer-Emmett-Teller method （BET）, ion chromatography （IC）, X-ray photoelectron spectroscopy （XPS）, and X-ray diffraction （XRD）. The characterized results indicated that the deposition of sulfates and nitrates on the surface made the catalyst deactivated. Water washing, thermal regeneration and reductive regeneration were used to regenerate the deactivated Mn-Ce/TiO2. And water washing showed best performance on the regeneration of poisoned catalysts, especially with ultrasonic vibration. The Mn-Ce/TiO2 catalyst showed high stability under a series of deactivation-regeneration experiments for ten cycles.

The Impact of Water Level Decline on Water Quality in the Epilimnion of Lake Kinneret (Israel): Perennial Perspectives

Long term record (1933-2014) of Water Level (WL), nutrient concentrations, plankton densities, and temperatures in the epilimnion of Lake Kinneret was analyzed. The aim is to identify if water quality is deteriorated when the WL is low. It was found that water temperature increased and the composition and biomass of plankton communities were modified. Nitrogen and TDP decreased but TP slightly increased in the epilimnion during low WL conditions. The quality of epilimnetic water was not deteriorated and followed by a slight oligotrophism trend.

Study on the Reservoir Water Quality Change Rule in Northern China

Water quality index of reservoir source water were tracked during three years in a north frigid area,the effect on supplied water quality was also studied.Based on the analysis of the monitoring data during the same season,the reservoir source water had typical and seasonal variation characteristics that was divided into four periods including the icebound period,spring period(or peach blossom period),stable period in summer and autumn and winter period.The icebound period was charactered by the typical low temperature and turbidity,pH and oxygen consumption decreased gradually showed that the gradually anaerobic trend existed in the reservoir.In May as the reservoir completely thawed,upstream water inflow and the total pollutant in the reservoir gradually increased,but the bottom of reservoir bottom was stable in the anaerobic state temporarily.The state completely disappeared,various index increased significantly in the middle of July.The water had high chroma characteristics,chroma and turbidity increased significantly in the summer and autumn(7-11months),but stability of water quality was poor because of rainfall.The reservoir gradually froze after the middle of November and the flow of water decreased.The peak of chroma appeared a month later than the water temperature.Due to the water turbidity was low,and the floc was small and light,the conventional water purification process design based on removal of turbidity achieved removal of chroma through a lot dosing of coagulant.

Slag-washing water of blast furnace power station with supercritical organic Rankine cycle

Organic Rankine cycle(ORC) power plant operating with supercritical parameters supplied by low temperature slag-washing water(SWW) of blast furnace was investigated.A schematic of such installation was presented with a description of its operation and the algorithm of calculations of a supercritical power plant.Two typical organic fluids with sufficiently low critical parameters were selected as candidate working fluids in the plant to study the efficiency of the system with different organic fluids.An analysis of the influence on the effectiveness of operation of a plant was carried out.With the same temperature of slag-washing water,the specific work in turbine of fluid R143a is 45% higher than that obtained for the fluid R125,however,the specific work in pump of fluid R143a is approximate equal into that one of the fluid R125.

Effect of Agents on Hydrate Formation and Low-Temperature Rheology of Polyalcohol Drilling Fluid

In order to ensure safe drilling in deep water and marine gas hydrate bearing sediments, the needed characteristics of drilling fluid system were analyzed. Moreover, the effect of different agents on hydrate formation and the low-temperature rheology of designed polyalcohol drilling fluid were tested, respectively. The results show that clay can promote gas hydrate growth, while modified starch and polyalcohol can inhibit hydrate formation to some extent, and PVP K90 has a good performance on hydrate inhibition. The influence of clay on low-temperature rheology of polyglycols drilling fluid is notable. Therefore, the clay-free polyalcohol drilling fluid is suitable for deep water and marine gas hydrate drilling under optimal conditions.

Development and application of multi-field coupled high-pressure triaxial apparatus for soil

The increasing severity of ground subsidence,ground fissure and other disasters caused by the excessive exploitation of deep underground resources has highlighted the pressing need for effective management.A significant contributing factor to the challenges faced is the inadequacy of existing soil mechanics experimental instruments in providing effective indicators,creating a bottleneck in comprehensively understanding the mechanisms of land subsidence.It is urgent to develop a multi-field and multi-functional soil mechanics experimental system to address this issue.Based soil mechanics theories,the existing manufacturing capabilities of triaxial apparatus and the practical demands of the test system,a set of multi-field coupled high-pressure triaxial system is developed tailored for testing deep soils(at depths of approximately 3000 m)and soft rock.This system incorporates specialized design elements such as high-pressure chamber and horizontal deformation testing devices.In addition to the conventional triaxial tester functions,its distinctive feature encompass a horizontal deformation tracking measuring device,a water release testing device and temperature control device for the sample.This ensemble facilitates testing of horizontal and vertical deformation water release and other parameters of samples under a specified stress conditions,at constant or varying temperature ranging from-40℃–90℃.The accuracy of the tested parameters meets the requirements of relevant current specifications.The test system not only provides scientifically robust data for revealing the deformation and failure mechanism of soil subjected to extreme temperature,but also offers critical data support for major engineering projects,deep exploration and mitigation efforts related to soil deformation-induced disaster.

低温与无水胁迫下凡纳滨对虾肌肉品质劣变标记蛋白识别

【目的】探明凡纳滨对虾(Litopenaeus vannamei)保活流通过程中低温和无水双重胁迫诱导肌肉品质劣变与差异表达蛋白之间的相关性,识别品质劣变的潜在标记蛋白。【方法】在模拟的海水环境中[溶解氧质量浓度为7.2 mg/L,温度控制在(12±1)℃]观察对虾在低温和无水胁迫下的生理反应,通过串联质谱标签蛋白质组学方法,分析环境胁迫导致的肝胰腺蛋白质组显著差异性变化,并将其与肌肉品质进行相关性分析。【结果】与正常对照组相比,低温组和低温+无水组分别鉴定了33和44个显著差异蛋白质(DEPs),这些蛋白质大多在溶酶体、糖酵解或糖异生、黏附等通路显著富集(P<0.05),同时胰蛋白酶-1、二肽基肽酶显著上调(P<0.05),而磷酸丙糖异构酶和醛脱氢酶显著下调(P<0.05)。此外,颜色和质构指标的变化与微管蛋白、凝溶胶蛋白、层黏连蛋白、内源性蛋白酶和代谢酶表达水平显著相关。【结论】本研究初次探明肝胰腺DEPs与肌肉品质间的内在联系,识别的典型DEPs可作为品质劣变的潜在标志蛋白,为监测无水运输期间凡纳滨对虾肌肉品质劣变提供分子靶标。

某锂矿低温熟化—水浸提锂和提纯高纯石英新工艺

皖南低品位热液蚀变型锂矿Li_(2)O含量0.21%,属于新类型锂矿资源,主要矿物成分有长石、石英、白云母、绿泥石,锂主要以晶格形式赋存于锂绿泥石中。新工艺采用-1 mm原矿筛分,+0.425 mm粒级进入磨矿,制备-0.425+0.074 mm合格粒级。脱泥后合格粒级产品经磁选得云母精矿,非磁性物浮选得到长石精矿和石英精矿,长石精矿和云母精矿分别进行提锂,石英精矿进行酸处理提纯得高纯石英。将原矿筛出的-0.074 mm细泥、再磨产生的-0.074 mm细泥、合格粒级搅拌擦洗产生的-0.074 mm细泥,合并为总泥进行后续提锂。试验结果表明:总泥、云母、长石分别采用低温熟化—水浸工艺提锂,累计得Li_(2)O浸出率88.78%,酸浸后石英精矿含SiO_(2)99.942%,Fe 4.38 mg/kg,达到高纯石英低端产品要求,提锂后的长石和云母浸渣产率54.48%,可用于建筑材料。浸出前后样品的XRD和SEM分析表明,硫酸低温熟化破坏了锂绿泥石晶格结构,H+代替锂绿泥石中Li+,将锂释放出来。新工艺降低了磨矿成本,锂浸出率高,兼顾云母、石英、长石的回收,减少了尾矿排放,提高了低品位热液蚀变型锂矿的综合利用水平。