Histological and functional assessment of a Takotsubo cardiomyopathy model established by immobilization stress.

INTRODUCTION: Takotsubo cardiomyopathy (TTC), also known as stress-induced cardiomyopathy, resembles acute heart failure syndrome but lacks disease-specific diagnosis and treatment strategies. TTC accounts for approximately 5-6% of all suspected cases of acute coronary syndrome in women. At present, animal models of TTC are often created by large amounts of exogenous catecholamines such as isoproterenol. However, isoproterenol injection cannot fully simulate the onset of stress-induced cardiomyopathy in humans since stress is not an instantaneous event. METHODS: Rats were immobilized for 6 h per day for 1-14 days. To examine whether the TTC model was successful, echocardiography was employed; Elisa detected serum sympathetic activation markers; and the Open-Field test (OFT) was used to analyze behavioral changes in rats after stress. Western blot and histology were used to assess sympathetic remodeling, inflammation levels, and fibrosis; qRT-PCR was used to explore the levels of fibrosis and myocardial hypertrophy. The electrical stability of ventricular was determined by electrophysiological testing. RESULTS: The rats showed severe stress behavior and local sympathetic remodeling of the heart after only 1 day of stress. After 3 days of stress, the induction of ventricular tachyarrhythmia increased prominently. The highest incidence of TTC in rats was at 5 days of immobilization stress. The pathological left ventricular remodeling caused by immobilization (IMO) stress includes inflammatory infiltration, fibrosis, and myocardial hypertrophy. CONCLUSIONS: Our study confirms the hypothesis that IMO stress can mimic Takotsubo cardiomyopathy, and the various effects on the heart depending on the duration of IMO stress. We observed the highest incidence of TTC occurred after 5 days of stress. Furthermore, there is a gradual occurrence of electrical and structural remodeling as the stress duration prolongs.

Induced domestication of humic reduction-denitrification coupled bacteria improved treatment of sediment: Performance, remediation effect, and metabolic mechanisms.

The high organic matter in river sediment primarily induces black and odorous rebound. Traditional humic-reducing bacteria demonstrate relatively single metabolic functions and restrain the remediation within complex sediment environments. In addition, Ca(NO3)2 is commonly utilized in synergistic with bioremediation to improve the reducing environment of sediments. In this study, a multifunctional bacterial community with humic reduction-denitrification coupled bacteria was domesticated by the step-feeding strategy in an anaerobic baffle reactor (ABR). The performance, remediation effect, and metabolic mechanisms were analyzed. The results indicated that humic-reducing bacteria (HRB) and denitrifying-humic-reducing bacteria (DF/HRB) have quinone-reduction and denitrification capabilities. The synergistic effect of DF/HRBs and Ca(NO3)2 was superior to HRBs and Ca(NO3)2 on the removal of total organic matter(TOM). Microbial community structure analysis revealed an enhanced relative abundance of denitrification and humic-reducing bacteria (e.g., Thauera, Pseudomonas, Sulfurospirillum, Desulfovibrio, Geobacter) in the DF/HRB, resulting in a superior synergistic effect of DF/HRBs with Ca(NO3)2. This work helps to present an innovative approach to domesticate humic-reducing bacteria suited for the remediation environment effectively. It also expands the application of humic-reducing bacteria for in-situ anaerobic remediation of river sediments.

The mechanism of C-N-S interconnection degradation in organic-rich sediments by Ca(NO3)2 - CaO2 synergistic remediation.

The rebound of black-odorous occurred in organic-rich sediments has become a critical issue due to its great harm to the ecological environment. Elements such as S, C, and N play a crucial role in the biogeochemical cycle of black-odorous rivers. As electronic acceptors, Ca(NO3)2 and CaO2 can effectively remove acidified volatile sulfide (AVS) and organic matter to control the black-odorous rebound. However, the remediation mechanisms in organic-rich sediments by Ca(NO3)2 and CaO2 are unclear. The present study explored the mechanism of C-N-S interconnection degradation in organic-rich urban river sediments by adding different ratios and sequences of Ca(NO3)2 and CaO2. The results showed that Ca(NO3)2 remediation followed by CaO2 and the accepted electron ratio 1:1 of Ca(NO3)2 to CaO2 is an effective method for controlling the rebound of black-odorous and reducing the accumulation NO2--N. Mainly attributed to that, CaO2 enhanced the degradation of organic matter by stimulating enzymatic activities in the sediments, which is also the main reason for controlling the rebound of black-odorous. Since CaO2 releases O2 and •OH, which inhibit nosZgenes, NO2--N accumulates when remedied simultaneously with Ca(NO3)2 and CaO2. Co-occurrence network analysis illustrated that sulfur-driven autotrophic denitrification bacteria, heterotrophic denitrifying bacteria, and sulfate-reducing bacteria interact strongly inside one module, clarifying a solid interaction of C-N-S substances among these bacteria. Our results reveal the C-N-S interconnection degradation mechanism and provide a new perspective on applying biochemical remediation in organic-rich urban river sediments.

Fluorescein diacetate hydrolytic activity as a sensitive tool to quantify nitrogen/sulfur gene content in urban river sediments in China.

The relative abundance of functional genes used to quantify the abundance of functional genes in communities is controversial. Quantitative PCR (qPCR) technology offers a powerful tool for quantifying functional gene abundance. However, humic substances can inhibit qPCR in sediment/soil samples. Therefore, finding a convenient and effective quantitative analysis method for sediment/soil samples is necessary. The functional genes and physicochemical properties in sediments with different-level pollutions were analyzed in this study. Correlations between physicochemical properties and the relative abundance of functional genes were used to test whether relative abundance in gene prediction quantifies the abundance of functional genes. The abundance of functional genes could be corrected by multiplying the fluorescein diacetate (FDA) hydrolytic rates by the relative abundance of functional genes since the FDA assay has been widely used as a rapid and sensitive method for quantifying microbial activity in sediments. Redundancy analysis showed significant interrelations between the functional genes and the physicochemical properties of sediments. The relative abundance of functional genes is unreliable for quantifying the abundance of functional genes because of the weak correlation (R < 0.5, P < 0.05) between different pollutants and the relative abundance of functional genes. However, a significant positive correlation between concentrations of different pollutants and the activities of associated enzymes was obtained (R > 0.933, P < 0.05), which revealed that the abundance of functional genes could be reliably quantified by the relative abundance and FDA hydrolytic rate. This study proposed an alternative method besides qPCR to quantify the absolute abundance of functional genes, which overcomes the problem of humic interference in the quantitative analysis of sediment/soil samples.

Single-cell sequencing combined with machine learning reveals the mechanism of interaction between epilepsy and stress cardiomyopathy.

Background: Epilepsy is a disorder that can manifest as abnormalities in neurological or physical function. Stress cardiomyopathy is closely associated with neurological stimulation. However, the mechanisms underlying the interrelationship between epilepsy and stress cardiomyopathy are unclear. This paper aims to explore the genetic features and potential molecular mechanisms shared in epilepsy and stress cardiomyopathy. Methods: By analyzing the epilepsy dataset and stress cardiomyopathy dataset separately, the intersection of the two disease co-expressed differential genes is obtained, the co-expressed differential genes reveal the biological functions, the network is constructed, and the core modules are identified to reveal the interaction mechanism, the co-expressed genes with diagnostic validity are screened by machine learning algorithms, and the co-expressed genes are validated in parallel on the epilepsy single-cell data and the stress cardiomyopathy rat model. Results: Epilepsy causes stress cardiomyopathy, and its key pathways are Complement and coagulation cascades, HIF-1 signaling pathway, its key co-expressed genes include SPOCK2, CTSZ, HLA-DMB, ALDOA, SFRP1, ERBB3. The key immune cell subpopulations localized by single-cell data are the T_cells subgroup, Microglia subgroup, Macrophage subgroup, Astrocyte subgroup, and Oligodendrocytes subgroup. Conclusion: We believe epilepsy causing stress cardiomyopathy results from a multi-gene, multi-pathway combination. We identified the core co-expressed genes (SPOCK2, CTSZ, HLA-DMB, ALDOA, SFRP1, ERBB3) and the pathways that function in them (Complement and coagulation cascades, HIF-1 signaling pathway, JAK-STAT signaling pathway), and finally localized their key cellular subgroups (T_cells subgroup, Microglia subgroup, Macrophage subgroup, Astrocyte subgroup, and Oligodendrocytes subgroup). Also, combining cell subpopulations with hypercoagulability as well as sympathetic excitation further narrowed the cell subpopulations of related functions.

Utilization of brewery wastewater for culturing yeast cells for use in river water remediation.

Successful in situ bio-augmentation of contaminated river water involves reducing the cost of the bio-agent. In this study, brewery wastewater was used to culture yeast cells for degrading the COD(Cr) from a contaminated river. The results showed that 15 g/L of yeast cells could be achieved after being cultured in the autoclaved brewery wastewater with 5 mL/L of saccharified starch and 9 g/L of corn steep liquor. The COD(Cr) removal efficiency was increased from 22% to 33% when the cells were cultured using the mentioned method. Based on the market price of materials used in this method, the cost of the medium for remediating 1 m3 of river water was 0.0076 US dollars. If the additional cost of field implementation is included, the total cost is less than 0.016 US dollars for treating 1 m3 of river water. The final cost was dependent on the size of remediation: the larger the scale, the lower the cost. By this method, the nutrient in the brewery wastewater was reused, the cost of brewery wastewater treatment was saved and the cost of the remediation using bio-augmentation was reduced. Hence, it is suggested that using brewery wastewater to culture a bio-agent for bio-augmentation is a cost-effective method.

Analysis of the Influence of Network Continuous Care on the Quality of Life of Patients with Coronary Artery Disease (CAD) after PIC.

Studies have shown that most patients after PCI cannot adhere to the cardiac rehabilitation program. The survey found that due to the lack of secondary prevention of cardiac rehabilitation, the phenomenon of drug reduction and withdrawal after PCI is very common after discharge, leading to recurrence of the patient's disease or worsen and repeated hospitalizations, so continuity of care is very important. In this paper, in addition to proposing a network care continuum with artificial intelligence handler in order to improve the healthcare system and provide new ideas for improving the postoperative recovery of CHD patients, we analyze the impact of PCI on the coronary heart disease patients' PCI postoperative quality of life. In the method part, this article introduces the concepts of continuation care and PCI after surgery, introduces the marker delivery algorithm in the field of artificial intelligence, and introduces the SF-36 scale for patient quality of life analysis. This article designs an experiment combining artificial intelligence processors to carry out network continuity care for patients and divides 100 eligible patients into an experimental group and a control group. In the analysis part, the two groups of patients were analyzed in terms of general data comparison, physical function, biochemical indicators, quality of life, and dependence. It can be seen from the experimental analysis that the anxiety and depression of the two groups of subjects have different degrees of decline. The HAMA value of the experimental group is 9.06 ± 0.77, and the HAMD value is 9.18 ± 1.20, which is significantly lower than that of the control group, P < 0.05. It can be seen that the use of network continuation care can reduce the negative emotions of patients more than general care. Through psychological counseling and postoperative follow-up, it can improve the optimism and positive emotions of the patients, reduce the negative emotions of the patients, and improve it to a certain extent.

Control of membrane fouling during hyperhaline municipal wastewater treatment using a pilot-scale anoxic/aerobic-membrane bioreactor system.

Membrane fouling limits the effects of long-term stable operation of membrane bioreactor (MBR). Control of membrane fouling can extend the membrane life and reduce water treatment cost effectively. A pilot scale anoxic/aerobic-membrane bioreactor (A/O-MBR, 40 L/hr) was used to treat the hyperhaline municipal sewage from a processing zone of Tianjin, China. Impact factors including mixed liquid sludge suspension (MLSS), sludge viscosity (micro), microorganisms, extracellular polymeric substances (EPS), aeration intensity and suction/suspended time on membrane fouling and pollution control were studied. The relationships among various factors associated with membrane fouling were analyzed. Results showed that there was a positive correlation among MLSS, sludge viscosity and trans-membrane pressure (TMP). Considering water treatment efficiency and stable operation of the membrane module, MLSS of 5 g/L was suggested for the process. There was a same trend among EPS, sludge viscosity and TMP. Numbers and species of microorganisms affected membrane fouling. Either too high or too low aeration intensity was not conducive to membrane fouling control. Aeration intensity of 1.0 m3/hr (gas/water ratio of 25:1) is suggested for the process. A long suction time caused a rapid increase in membrane resistance. However, long suspended time cannot prevent the increase of membrane resistance effectively even though a suspended time was necessary for scale off particles from the membrane surface. The suction/suspended time of 12 min/3 min was selected for the process. The interaction of various environmental factors and operation conditions must be considered synthetically.

The remediation of urban freshwater sediment by humic-reducing activated sludge.

Organic pollution of urban rivers caused by stormwater discharge is a global problem. Traditional bioremediation of organic matters (OM) by aerobes could be restrained in anaerobic environments, which usually occurr in polluted river sediments. In this study, an anaerobic remediation technology has been developed to enhance the in-situ removal of organic matters in river sediments, humic-reducing sludge (HRS) was adapted from traditional activated sludge; it exhibited a strong humic-reducing ability. Nitrate and biostimulants were used to stimulate HRS. The change of microbial community between AQDS-adapted and non-AQDS-adapted was analyzed, and the effect of HRS augmentation and Nitrate/biostimulant addition on TOM removal were discussed from the perspective of light and heavy fraction organic matters (LFOM and HFOM). The results have indicated that, after adaptation, HRS had increased the bacterial population of Anaerolineales and Desulfuromonadales, which was related to the carbon metabolism and electron-transfer ability. On the other hand, the adaptation decreased the population of bacteria related to the sulfur/sulfate circulation. This characteristic of the HRS was potentially benificial to reducing the occurrence of black-odor phenomenon. Also, the removal efficiency of TOM in sediment was significantly improved by using HRS because HRS could facilitate the removal of HFOM. Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated that the advantage of decomposing HFOM using HRS resulted from the fact that the HFOM contained redox mediators to facilitate humic-reducing respiration. In addition, nitrate appeared to be crucial for the enhancement of HRS in sediments. These findings have allowed for the development of a technology for in-situ anaerobic remediation of urban river sediments. They could also help to understand humic-reducing mechanism in the sediment during anaerobic bioremediation.

Evaluation and correction on quinones' quantification errors: Derived from the coexistence of different quinone species and pH-sensitive feature.

Quinones are becoming an essential tool for refractory organics treatment, while their quantification may be not well-considered. In this paper, two kinds of potential errors in quantification were evaluated in multiple pH conditions. They were derived from the coexistence of oxidized/reduced quinone species (Type I) and pH-sensitive feature (Type II), respectively. These errors would remarkably influence the accuracy of quantification while they haven't been emphasized. Thus, to elaborate the relationship between the two types of errors and the absorbance or pH conditions, three typical quinones [Anthraquinone-1-sulfonate (α-AQS), anthraquinone-2,6-disulfonate (AQDS) and lawsone] were selected and their acid dissociation coefficients (pKa) as well as UV-Vis spectra were determined. Results revealed that, for Type I, the relative error (RE) of α-AQS concentration would exceed the limit (5%) when reduced α-AQS was below 48% of total α-AQS. Similar results were found for lawsone. However, the RE can be eliminated by the equation established in this paper. For Type II, the pH-sensitive feature was related to the pKa values of quinones. Absorbances of α-AQS and lawsone would change remarkably with pH variation. Therefore, a model for correction was established. Analog data showed high consistency with experimental data [r = 0.995 (n = 25, p < 0.01) and r = 0.997 (n = 36, p < 0.01), for lawsone and α-AQS respectively]. Especially, the determination of AQDS concentrations was noticed to be pH-independent at 437 nm under pH 4.00 to 9.18 conditions. Based on these features, a comprehensive data solution was proposed for handling these errors.

Application potential of aerobic denitrifiers coupled with a biostimulant for nitrogen removal from urban river sediment.

Aerobic denitrifiers coupled with a denitrification agent were applied in the sediment of an urban river for the bioremediation of nitrogen pollution. The results revealed that 14.7% of the total nitrogen in the sediment was removed after 115 days of treatment and the nitrate nitrogen concentration removal rate was enhanced in the overlying water. Compared with the control, the total transferable nitrogen in the sediment increased from 0.097 to 0.166 mg/g, indicating that more nitrogen is likely to be involved in the biogeochemical cycling of nitrogen. Increased urease activity indicated the possible further potential of nitrogen biodegradation, while the decreased protease pointed to the low concentration of protein remaining in the sediment. Sequencing revealed that the bacterial community diversity in the sediment increased significantly after 43 days of treatment and that the effect persisted. Compared with other microcosms, the dominant phyla in the sediment after 43 days were Firmicutes, Elusimicrobia, Spirochaetae and Fibrobacteres; whereas, after 115 of treatment, the dominant bacteria were Nitrospirae, Deferribacteres and Chloroflexi. The dominant bacteria in the sediment are mainly associated with nitrogen cycling and thus contributed considerably to nitrogen removal in the sediment. Overall, the direction of species succession was similar to natural succession; namely, there were no undesirable ecological risks involved. This study highlights the possible benefits and feasibility of using bioaugmentation technology coupled with biostimulation to remediate nitrogen-polluted sediments.

[Characteristics of Advanced Treatment of Treated Petrochemical Water by O3-BAC and Analysis of Consortium Structure].

The advanced treatment of treated petrochemical water by Ozone-Biological Activated Carbon (O3-BAC) was carried out in this study. The effect of O3 on the removal of Chemical Oxygen Demand (COD) and Spectral Absorption Coefficient (UV254) were investigated. The characteristics of organic matter and the microbial consortium structure of BAC were also investigated at 20 mg·L-1 of O3 dosage concentration, 40 min of O3 single stage contact time and 1.5 h of the empty bed residence time of BAC. Results showed that the effluent COD concentration of O3-BAC was 24 mg·L-1 with the removal efficiency of 40.4%. The COD removal efficiency of O3-BAC was higher than that for the BAC process. The UV254 removal efficiency of O3-BAC was 55.1%. Meanwhile, UV254 correlated with COD with a correlation coefficient of 0.89. The percentage of dissolved organic matters with relative molecular weight less than 1×103 increased from 69.0% to 87.0% after O3 oxidation. The NPOC removal efficiency of O3-BAC (45.8%) was higher than that of the BAC process (23.0%). The NPOC removal efficiency of the BAC unit was mainly achieved by reduction of dissolved organic matters with relative molecular weight less than 1×103. GC-MS analysis results showed that organic substances such as alkanes, unsaturated esters, and phenols had been removed by O3 oxidation. The micro ecological environment of the BAC unit had been significantly improved after O3 oxidation, and the genera with relative abundance over 1.0% increased from 6 to 11. The combined O3-BAC system can be applied to the advanced treatment of petrochemical treated water.

Characterization of primary precipitate composition formed during co-removal of Cr(VI) with Cu(II) in synthetic wastewater.

BACKGROUND, AIMS AND SCOPE: Hexavalent chromium [Cr(VI)] cannot react with either carbonate or hydroxide to form chromium precipitates. However, by using a precipitation technology to treat plating wastewater containing Cr(VI), Cu(II), Ni(II) and Zn(II), approximately 78% of Cr(VI) (initial 60 mg/L) was co-removed with the precipitation of Cu(II), Ni(II) and Zn(II) (each 150 mg/L) by dosing with Na2CO3 (Sun 2003). Direct precipitation by forming Cu(II)-Cr(VI) precipitates followed by adsorption of Cr(VI) onto freshly formed Cu-precipitates was subsequently found to be the main mechanism(s) involved in Cr(VI) co-removal with Cu(II) precipitation by dosing Na2CO3 stepwise to various pH values (Sun et al. 2003). This study was. carried out to further characterize the formation of primary precipitates during the early stages of copper precipitation and simultaneous removal of Cr(VI) with Cu(II). METHODS: Test metal-solutions were prepared with industrial grade chemicals: CuCl2 x 2H2O, Na2SO4 and K2Cr2207. NaCO3 was added drop-wise to synthetic metal-solution to progressively increase pH. For each pH increment, removal of soluble metals was detected by atomic absorption spectrophotometer (AAS) and surface morphology of precipitates was analyzed by scanning electron microscope (SEM). To further characterize the formation of primary precipitates, a series of MINEQL+ thermodynamic calculations/analyses and equilibrium calculations/ analyses were conducted. RESULTS AND DISCUSSION: MINEQL+ thermodynamic calculation indicated that, for a system containing 150 mg/L Cu(II) and 60 mg/L Cr(VI) with gradual Na2CO3 dosing, if any precipitates can be formed at pH 5.0 or lower, it should be in the form of CuCrO4. Comparison tests using systems containing the same equivalent of Cu(II) plus Cr(VI) and Cu(II) plus SO4(2-) showed that the precipitation occurred at a pH of around 5.0 in the Cu(II)-Cr(VI) system and around 6.0 in the Cu(II)-SO4(2-) system. The discrepancy of the precipitation was indeed caused by the formation of Cu-Cr precipitates. The initiation of copper removal at pH around 5.0 for the Cu-Cr co-removal test was not attributable to the formation of Cu-CO3 precipitates, instead, it was most likely through the formation of insoluble Cu-Cr precipitates, such as CuCrO4 and CuCrO4 x 2Cu(OH)2. Experimental tests, equilibrium calculations, MINEQL+ thermodynamic calculations and surface morphologies for systems using higher concentrations of Cu(II) and Cr(VI) further verified the most probable composition of primary precipitates is copper-chromate. CONCLUSION: In the Cu-Cr co-removal test with Na2O3 dosing to increase pH and induce metal precipitation, copper-chromate precipitates are the primary precipitates produced and contribute to the initial simultaneous removal of copper and chromium.

The influence of chemically enhanced backwash by-products (CEBBPs) on water quality in the coagulation-ultrafiltration process.

This study was conducted to investigate the typical types of chemically enhanced backwash by-products (CEBBPs) produced in the chemically enhanced backwash (CEB) process and the influence of CEB parameters on typical CEBBPs in the coagulation-ultrafiltration process. Health risk assessment was applied to assess the potential adverse health effect from exposure to effluent after the optimal CEB. The results indicated that backwash reagent of sodium hypochlorite reacted with organic matter to produce CEBBPs, including 12 species of volatile halogenated organic compounds (VHOCs) and 9 species of haloacetic acids (HAAs) during CEB process. The amount of HAAs was higher than that of VHOCs indicating that the content of primary HAA precursor (hydrophilic organic matter) was high in raw surface water and the coagulation process could not lower the hydrophilic organic matter concentration. After comprehensive consideration of the influence of single factors on the CEBBP formation and membrane cleaning effect, the optimal CEB parameters was 4 min of backwash duration, 120 min of backwash interval, 20 L/(m(2)·h) of backwash flux, and 25 mg/L of reagent concentration. Under the optimum CEB cleaning parameters, the effluent did not pose non-carcinogenic risk to local residents but could pose potential carcinogenic risk.

A case study of an enhanced eutrophication model with stoichiometric zooplankton growth sub-model calibrated by Bayesian method.

Urban lakes in China have suffered from severe eutrophication over the past several years, particularly those with relatively small areas and closed watersheds. Many efforts have been made to improve the understanding of eutrophication physiology with advanced mathematical models. However, several eutrophication models ignore zooplankton behavior and treat zooplankton as particles, which lead to the systematic errors. In this study, an eutrophication model was enhanced with a stoichiometric zooplankton growth sub-model that simulated the zooplankton predation process and the interplay among nitrogen, phosphorus, and oxygen cycles. A case study in which the Bayesian method was used to calibrate the enhanced eutrophication model parameters and to calculate the model simulation results was carried out in an urban lake in Tianjin, China. Finally, a water quality assessment was also conducted for eutrophication management. Our result suggests that (1) integration of the Bayesian method and the enhanced eutrophication model with a zooplankton feeding behavior sub-model can effectively depict the change in water quality and (2) the nutrients resulting from rainwater runoff laid the foundation for phytoplankton bloom.

Characterization of adsorbent composition in co-removal of hexavalent chromium with copper precipitation.

Mechanisms of hexavalent chromium co-removal with copper precipitation by dosing Na2CO3 were studied with a series of well-designed batch tests using solutions containing 150 mg l-1 Cu(II) and 60 mg l-1 Cr(VI). It was found that direct precipitation of chromium through formation of copper-chromium bearing precipitates (in the form of CuCrO4) was one of the main mechanisms contributing to chromium co-removal at pH close to 5.0, and adsorption of chromium at a higher pH by freshly formed copper-carbonate precipitates (adsorbent) contributed to further chromium co-removal. Since, according to solubility products, neither copper-carbonate nor copper-hydroxide precipitates can be produced at pH around 5.0 for a pure 150 mg l-1 copper precipitation, characterization of copper-carbonate precipitates (adsorbent) was carried out through developing pC-pH curves of the systems by both equilibrium calculations and MINEQL+ 4.5 (a chemical equilibrium modeling software), and also through laboratory determination of the precipitate composition, such as gravimetric analyses, inorganic carbon percentage and EDAX spectrum analyses. CuCO3.Cu(OH)2, or a combination of CuCO3.Cu(OH)2 (in majority) and Cu(OH)2 (in minority) were suggested to be the major constituent of the precipitates obtained from the copper solution with Na2CO3 dosing.

[EPS, SMP and microbial biodiversity under the oligotrophic environment].

In order to investigate the extracellular polymeric substances (EPS), soluble microbial product (SMP) and microbial biodiversity of the sludge lacking of nutrition, to provide evidence for optimizing MBR's operation and lessening membrane fouling, a series of experiments were undertaken under the oligotrophic environment using the sludge from the MBR of Tianjin University. The contents of EPS and SMP were determined, and microbial biodiversity was analyzed by PCR-DGGE technology and cloning-sequencing. Furthermore, the sequences were used for homology analysis and then the phylogenetic tree was constructed. In the initial stage, the EPS and SMP contents raised from 15.04 mg/g and 0 mg/g to 17.99 mg/g and 3.29 mg/g, respectively. Along with the experiment progress, the EPS content dropped to 2.40 mg/g; but the SMP content varied around 3.5 mg/g. This indicates that the EPS and SMP possess the buffer action towards the variation of the environment, and the microorganism can utilize the EPS and SMP under the condition of oligotrophic. Because of the utilization of the EPS and SMP, the Shannon index of the sludge raised from 0.81 to 1.09. Then, it began to decline and stabilized at 0.95 finally. The clone and sequence results reflect that the microbial structure is very rich, and most of the dominant species are uncultured bacterium. Some of the bacterium, which are mostly belong to Bacteroidetes, Flavobacterium, Saprospiraceae and Firmicutes, can degrade the EPS and SMP by secreting protein and polysaccharide hydrolyzing enzymes.

[Roles of EDTA on phytoremediation of combined contamination in dredged sewage river sediment].

Pot experiments were conducted to study the roles of EDTA in phytoremediation of heavy metal-organic contaminated dredged sewage river sediment by Lolium multiflorum L. 3 mmol x kg(-1) EDTA was added to sediment through three manners (once, twice and three times, respectively). The results showed that: with adding EDTA to the sediment. (1) The accumulation amount of heavy metals to Lolium multiflorum L. increased, especially by added EDTA three times. Compared with the control, the accumulation of Pb, Zn, Cu, Ni, Cd in shoots increased 2.74, 1.99, 1.59, 1.55 and 7.78 times by added EDTA three times. The net increment was 32.33 mg x kg(-1), 1 393.56 mg x kg(-1), 64.42 mg x kg(-1), 36.57 mg x kg(-1) and 10.33 mg x kg(-1), respectively. Furthermore, the concentration of chlorophyll decreased by 42% with 3 times EDTA addition, while the concentration of chlorophyll has no significant change with once EDTA addition. (2) pH hasn't much change, while NH4OAc and DTPA extractable heavy metal amount from sediment increased significantly. (3) The bulk percentage of big particle sediment increased. By added EDTA three times to sediment, the average particle size of sediment increased, while specific surface area and crystal lattice intensity decreased, which were contributed to the desorption of heavy metal from sediment particle. (4) Compared with the control, the amount of microorganism in sediment was increased 1.33 times and 1.47 times with adding EDTA twice and three times. The urease activity decreased, while the catalase activity hasn't much change. (5) TOC content was increased.

[Effect of freeze-thaw treatment on characteristics and dewaterability of sewage river sediment].

This research employed the freeze-thaw treatment method under nature and manual condition to reduce the moisture content of the contaminated sewage river sediment, thus reduce the secondary pollution to environment during remediation of sewage river. Experimental results show that the freeze-thaw treatment influences the sediment dewaterability and characteristics, such as specific resistance to filtration, moisture content, granule distribution, pollutant content of leachate. After freeze-thaw treatment, the surface area of the sediment became decreased, average granule diameter increased and the solid and water separated clearly. Moisture content was decreased from 83% - 85% to 50% - 60%. Volume cavernous water, capillary water and adhesion water dissociated from the sediment, thus sediment dewaterability is enhanced greatly. The specific resistance was reduced from (1.2 - 4.1) x 10(9)s(2)/g to (3.8 - 5.2) x 10(7)s(2)/g. On the other hand, leachate characteristics changed a lot: suspend solid (SS) content was reduced from 1 000 - 1 200 mg/kg to 340 - 380 mg/kg, ammonia nitrogen content was reduced from 150 - 170 mg/kg to 100 - 120 mg/kg, BOD5 content was reduced from 300 - 310 mg/kg to 50 - 60 mg/kg, however oil content was increased from 1 - 2 mg/kg to 11 - 12 mg/kg. Therefore, if the sediment is not contaminated by oil, the leachate pollution can be reduced by freeze-thaw treatment method.

Co-removal of hexavalent chromium through copper precipitation in synthetic wastewater.

The mechanisms of hexavalent chromium [Cr(VI)] co-removal with copper [Cu(II)] during homogeneous precipitation were studied with batch tests using a synthetic solution containing Cr(VI) and Cu(II). Metal precipitation was induced by adding Na2CO3 stepwise to different pH, and the respective removals of Cu(II) and Cr(VI) were measured. At the same time, the relative quantities of Cu(II) and Cr(VI) in the precipitates were also analyzed to establish their stoichiometric relationship. The results indicated that, in a solution containing 150 mg/L Cu(II) and 60 mg/L Cr(VI), the initial co-removal of Cr(VII with Cu(II) began at pH 5.0 and completed at pH 6.2. At pH 5.0-5.2, coprecipitation took place through the formation of copper-chromium-bearing solids [such as CuCrO4 and/or CuCrO4 x 2Cu(OH)2]. Thereafter, the remaining soluble copper started to react with carbonate in a heterogeneous environment to form the negatively charged basic copper carbonate precipitates [CuCO3 x Cu(OH)2], which subsequently adsorbed additional Cr(VI) (or HCrO4-) at pH 5.2-6.2. The maximum Cr(VI) co-removal took place at pH 6.2. Between the two mechanisms, co-precipitation accounted for about 29% of the total chromium's co-removal while the remaining 71% was attributed to surface adsorption, mainly through electrostatic attraction and ligand exchange. When the solution pH was increased to beyond 7.5, a surface charge reversal took place on the basic copper carbonate solids, and this led to some Cr(VI) desorption. Thus, the extent of Cr(VI) adsorption is highly pH dependent.