Stimulating anaerobic digestion to degrade recalcitrant organic pollutants: Potential role of conductive materials-led direct interspecies electron transfer.

This review aims to provide a comprehensive understanding of the potential of CMs-dominated DIET in the degradation of recalcitrant organic pollutants in AD. The review covers the mechanisms and efficiencies of recalcitrant organic pollutant degradation by CMs-dominated DIET, the comparison of degradation pathways between DIET and chemical treatment, recent insights on DIET-enhanced degradation, and the evaluation of the potential and future development of CMs-dominated DIET. The review emphasizes the importance of coupled syntrophic microorganisms, electron flux, and physicochemical properties of CMs in enhancing the degradation performance of AD. Additionally, it highlights the advantages of DIET-led syntrophic metabolism over traditional oxidation technologies in terms of environmental friendliness and efficiency. Finally, the review acknowledges the potential risks associated with introducing CMs into AD systems and provides guidance for waste treatment and energy recovery.

Conductive materials as fantastic toolkits to stimulate direct interspecies electron transfer in anaerobic digestion: new insights into methanogenesis contribution, characterization technology, and downstream treatment.

Direct interspecies electron transfer (DIET) stimulated by conductive materials (CMs) enables intercellular metabolic coupling that can address the unfavorable thermodynamical dilemma inherent in anaerobic digestion (AD). Although the DIET mechanism and stimulation have been extensively summarized, the methanogenesis contribution, characterization techniques, and downstream processes of CMs-led DIET in AD are surprisingly under-reviewed. Therefore, this review aimed to address these gaps. First, the contribution of CMs-led DIET to methanogenesis was re-evaluated by comparing the effect of various factors, including volatile fatty acids, free ammonia, and functional enzymes. It was revealed that AD systems are usually intricate and cannot allow the methanogenesis stimulation to be singularly attributed to the establishment of DIET. Additionally, considerable attention has been attached to the characterization of DIET occurrence, involving species identification, gene expression, electrical properties, cellular features, and syntrophic metabolism, suggesting the significance of accurate characterization methods for identifying the syntrophic metabolism interactions. Moreover, the type of CMs has a significant impact on AD downstream processes involving biogas purity, sludge dewaterability, and biosolids management. Finally, the central bottleneck consists in building a mathematical model of DIET to explain the mechanism of DIET in a deeper level from kinetics and thermodynamics.

Nitrogen removal of decentralized swine wastewater by pilot-scale source reduction - anaerobic baffled reactor - zoning constructed wetlands at low temperatures.

The study developed a cost-effective integrated technology to treat swine wastewater at the pilot-scale small pigsty. The swine wastewater, which was separated rinse water after flowing through the slatted floor and the innovatively constructed liquid-liquid separate collection device, was subsequently pumped into an anaerobic baffled reactor (ABR) and then through zoning constructed wetlands (CWs) comprised of CW1, CW2, and CW3. The liquid-liquid separate collection device effectively reduced COD, NH4-N, and TN by 57.82%, 52.39%, and 50.95%, respectively. The CW1 and CW2 enhanced TN removal and nitrification, respectively, through rapid adsorption-bioregeneration of zeolite. Moreover, rice straws were used as solid carbon sources in CW3 to successfully promote denitrification at 16.0 g/(m3·d). The integrated technology (slatted floor-liquid liquid separate collection-ABR-CWs) reduced COD, NH4-N, and TN by 98.17%, 87.22%, and 87.88%, respectively, at approximately 10 °C. Microbial analysis results confirmed that the CWs exhibited apparent functional zoning, with denitrifiers dominating in CW3, nitrifiers dominating in the zeolite layers of CW1 and CW2, and denitrifiers dominating in the brick slag layers of CWs. This cost-effective integrated technology demonstrated significant potential for treating swine wastewater at low temperatures.

Development, dilemma and potential strategies for the application of nanocatalysts in wastewater catalytic ozonation: A review.

With the continuous development of nanomaterials in recent years, the application of nanocatalysts in catalytic ozone oxidation has attracted more and more researchers' attention due to their excellent catalytic properties. In this review, we systematically summarized the current research status of nanocatalysts mainly involving material categories, mechanisms and catalytic efficiency. Based on summary and analysis, we found most of the reported nanocatalysts were in the stage of laboratory research, which was caused by the nanocatalysts defects such as easy aggregation, difficult separation, and easy leakage. These defects might result in severe resource waste, economic loss and potentially adverse effects imposed on the ecosystem and human health. Aiming at solving these defects, we further analyzed the reasons and the existing reports, and revealed that coupling nano-catalyst and membrane, supported nanocatalysts and magnetic nanocatalysts had promising potential in solving these problems and promoting the actual application of nanocatalysts in wastewater treatment. Furthermore, the advantages, shortages and our perspectives of these methods are summarized and discussed.

Inhibition of biological acidification and mechanism of crotonaldehyde removal with glucose cometabolism.

Biological acidification is an effective method in the treatment or pretreatment of industrial wastewater. Crotonaldehyde is a typical characteristic organic pollutant in petrochemical wastewater, but its effect on biological acidification is unclear. To investigate the inhibitory characteristic of crotonaldehyde on biological acidification and the mechanism of crotonaldehyde removal, variations in volatile fatty acid (VFA) yields, enzyme activities, biodegradation products, and microbial community structures were investigated by batch experiments in the presence of crotonaldehyde. The results showed that crotonaldehyde caused a 50% effect concentration (EC50) on the specific acidogenic activity (SAA) of 204.17 mg/L before 24 h, and then, the inhibitory effect was removed after 48 h as the dosage of crotonaldehyde was less than 1000 mg/L. Accordingly, crotonaldehyde was completely reduced to crotonyl alcohol by nicotinamide adenine dinucleotide (NADH) or oxidized to (E)-crotonic acid by aldehyde dehydrogenase (DHO) after 48 h. Next, 1-buanol and n-butyric acid were further metabolites, while the n-hexanoic acid detected with high-concentration crotonaldehyde might be due to the ORB pathway with 1-buanol as an electron donor. The dominant bacterial communities were Clostridium_sensu_stricto_1, Clostridium_sensu_stricto_11, Clostridium_sensu_stricto_12, which were related to the biodegradation process of crotonaldehyde. The findings of this research could provide a theoretical underpinning for developing the biological technologies to pretreat crotonaldehyde wastewater.

Inhibitory effect of individual and mixtures of nitrophenols on anaerobic toxicity assay of anaerobic systems: Metabolism and evaluation modeling.

The single and combined inhibitory effects of different nitrophenols on the anaerobic toxicity assay (ATA) of anaerobic sludge and the variations in the content of extracellular polymeric substances (EPS) were investigated. The results indicated that 2,4-dinitrophenol (2,4-DNP) demonstrated the highest inhibitory effect, followed by 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP), and the combined effects of binary and ternary nitrophenols induced additive toxicity. Furthermore, 2,4-DNP, the dominant toxic nitrophenol, at various concentrations and toxicant ratios, was the major contributor to the combined inhibitory effects of the nitrophenol mixtures. Abundant EPS could be secreted by the anaerobic sludge under the inhibitory effects of toxic 2-NP, 4-NP, and 2,4-DNP at concentrations from 0 to 200 mg/L to resist the adverse effects of the external environment. The protein contents of both loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) exhibited a better linear positive correlation relationship (R2 > 0.92) with the inhibitory rates of 2-NP, 4-NP, and 2,4-DNP, indicating that the proteins generated in the EPS of anaerobic sludge could be a stress response. Therefore, increasing the concentration of the toxic nitrophenols could enhance the stress response and increase protein production. Parallel factor (PARAFAC) analysis for TB-EPS and LB-EPS further confirmed that the major proteins were tyrosine, tryptophan, and aromatic proteins. Moreover, with an increase in the concentrations of 2-NP, 4-NP, and 2,4-DNP from 0 to 200 mg/L, microbial cell lysis and death in anaerobic sludge could be increasingly severe. Thus, this study provides new insights into the inhibitory effects of nitrophenol mixtures, which are frequently found in pharmaceutical and petrochemical effluents, on anaerobic sludge.

Effect of carbon source conditions on response of nitrifying sludge to 3,5-dichlorophenol.

Nutritional conditions of activated sludge had a significant influence on nitrification inhibition response. This study comprehensively investigated the inhibition of 3,5-dichlorophenol (3,5-DCP) on nitrification of activated sludge with different C/N ratios and carbon source types. The corresponding extracellular polymeric substances (EPS), microbial communities and functional genes were analysed. The results indicated that the addition of carbon source would reduce the nitrification activity and nitrification sensitivity to 3,5-DCP, and the order of the EC50 was sequenced as sodium acetate > methanol > glucose. The response mechanisms of activated sludge under diverse carbon source conditions to 3,5-DCP were summarised as follows. When the 3,5-DCP content was increased from 0.4 mg/L to 0.8 mg/L, the protein content increased from 73.2 ± 2.6 mg/g SS ∼122.4 ± 4 mg/g SS to 92.2 ± 11.2 mg/g SS ∼130.8 ± 9.6 mg/g SS in the tightly bound EPS (TB-EPS). The increase of protein content was attributed to cellular self-protection mechanisms. Furthermore, fluorescence characteristic analysis revealed that tyrosine and tryptophan in loosely bound EPS (LB-EPS) might account for higher EC50 in activated sludge fed with methanol and sodium acetate. In addition, the redundancy analyses (RDA) showed activated sludge with organics enriched the resistant species, such as Proteobacteria and Patescibacteria, while activated sludge without organics enriched the sensitive species, such as Ferruginibacter. Finally, the nitrification genes were found to be consistent with nitrification activity. Thus, the findings provide new insights into nitrification inhibition mechanism under different carbon source conditions.

Single and joint inhibitory effect of nitrophenols on activated sludge.

In this study, single and joint inhibitory effects of nitrophenols on activated sludge and variations on the content of extracellular polymeric substances (EPS) were investigated. Results indicate that the nitrophenols adversely affected the organic and NH3-N removal of activated sludge and the adverse effect of nitrophenols on autotrophic bacteria was higher than that on heterotrophic bacteria. Further, 2,4-dinitrophenol (2,4-DNP) demonstrated the highest inhibitory effect, followed by 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP), and the combined effects of binary and ternary nitrophenols induced additive toxicity. At various concentrations and toxicant ratios, 2,4-DNP, as the dominant toxic nitrophenol, was the major contributor to the joint inhibition effects of the mixed nitrophenols. At lower concentrations of 2-NP (below 100 mg/L), 4-NP (below 50 mg/L), and 2,4-DNP (below 10 mg/L), large amounts of both tightly bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) were secreted for the normal physiological activities of the microbiological cells. After further stimulation with higher concentrations of 2-NP (above 100 mg/L), 4-NP (above 50 mg/L), and 2,4-DNP (above 10 mg/L), the inhibitory effect of nitrophenols on bacterial metabolism evidently increased. However, the EPS production sharply reduced, particularly with respect to protein production. Parallel factor analysis for TB-EPS and LB-EPS further confirmed that the major proteins were tyrosine, tryptophan, and aromatic proteins. Thus, this study provides new insights into the inhibitory effects of mixed nitrophenols, which are frequently found in pharmaceutical and petrochemical effluents.

Association of Thiamine Intake with Human Papillomavirus (HPV) Infection in American Women: A Secondary Data Analysis Based on the National Health and Nutrition Examination Survey from 2003 to 2016.

BACKGROUND Studies have shown that thiamine intake is associated with cervical cancer, but the relationship between thiamine and HPV infection remains unclear. In the present study, we used the National Health and Nutrition Examination Survey (NHANES) database to investigate whether HPV infection was associated with thiamine intake. MATERIAL AND METHODS A total of 13 471 women ages 18-59 years were selected from the NHANES database from 2003 to 2016. Using thiamine intake as the independent variable, HPV infection as the dependent variable, and sociodemographic data and other data as the covariates, we analyzed the relationship between thiamine and HPV infection by conducting a weighted logistic regression model in a cross-sectional research design. RESULTS The two-piecewise linear model indicated the inflection point of thiamine intake was 2.07 mg. On the left side of the inflection point, the difference in the thiamine intake of log2 conversion was related to the difference of 0.82 in HPV infection, which means that the increase of every 1 unit increase in thiamine intake is associated with the decrease of the HPV infection by 18%. On the right side of the inflection point, we did not observe a correlation between HPV infection and thiamine intake. CONCLUSIONS Thiamine intake is negatively correlated with HPV infection. Intake of an appropriate amount of thiamine can prevent HPV infection. The best preventive effect can be achieved when the intake is about 2 mg, and excessive intake will not increase the preventive effect.

A quantitative evaluation method for wastewater toxicity based on a microbial fuel cell.

A microbial fuel cell (MFC) was successfully developed as a toxicity biomonitoring system to enable a quick response to wastewater with unknown toxicity in toxic events. The objective was to quantitatively assess the toxicity of wastewater by a rapid method. Different concentrations of formaldehyde were introduced into the anode chamber, which led to different stages of voltage change. A relationship between the linear slope of the voltage drop stage and the formaldehyde concentration was established through dose-response fitting results. This relationship makes it possible to convert an unknown toxicity of wastewater into the equivalent concentration of formaldehyde. The minimum detection limit in this study was 13 mg/L formaldehyde equivalents. As the toxicity of the wastewater increased, the test time could be reduced to as low as 921 s or even shorter, with a detection error of 3-12 mg/L. By using this evaluation method, oxidized tail gas scrubber wastewater was identified as the main toxic wastewater component in a phenol acetone production plant.

Effect of influent pH on hydrolytic acidification performance and bacterial community structure in EGSB for pretreating crotonaldehyde manufacture wastewater after ozonation.

The objective of this work was to evaluate the effect of influent pH on the hydrolytic acidification (HA) performance and microbial community structure in an expanded granular sludge bed (EGSB) pretreating crotonaldehyde manufacture wastewater (CMW) after ozonation. The results showed that higher chemical oxygen demand (COD) removal rate (40.1%) and acidification degree (27.6%) were obtained at pH 8.0 than those at pH 6.0 and pH 4.0. The concentration of extractable extracellular polymeric substance (EPS) in the sludge gradually decreased with the pH decreasing from 8.0 to 4.0. A similar change was also observed for the concentration of total volatile fatty acids (TVFA) in the effluent. The optimal detoxification efficiency by the HA process was obtained at pH 8.0, with higher removal efficiency (all higher than 90%) of the main toxic pollutants (crotonaldehyde, 5-formyl-6-methyl-4,5-dihydropyran, etc.) and higher anaerobic biodegradation rate (44.5%) in biochemical methane potential (BMP) assay. Among the predominant genera, the Acinetobacter and Pseudomonas were possibly related to biodegradation of pollutants, since their higher relative abundance also coincided with the better performance of the HA process at pH 8.0.

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks.

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.

Advanced treatment of petrochemical secondary effluent by Fenton: performance and organics removal characteristics.

The Fenton process was used to treat petrochemical secondary effluent. The effects of initial pH, H2O2, and FeSO4·7H2O dosages on chemical oxygen demand (COD) removal, the dissolved organic matter (DOM) removal and the transformation and migration of typical organic matters during the treatment process were investigated. The results showed that the optimum conditions were initial pH of 3.0, H2O2 (30%) dosage of 0.4 mL/L, and FeSO4·7H2O dosage of 1.0 g/L. The highest COD removal efficiency of 61.9% could be achieved for this condition when the average influent COD was 78.5 mg/L. Most of the DOM in the petrochemical wastewater could be removed effectively by Fenton through direct oxidation and coagulation. For example, for trans-1,2-dichlorocyclopentane, results showed that 56.3% of it could be removed by Fenton oxidation, while 13.3% of it could be absorbed by the in situ generated Fenton chemical sludge. The Fenton process is simple and it is suitable for the advanced treatment of petrochemical secondary effluent.

The activated sludge metabolic characteristics changing sole carbon source from readily biodegradable acetate to toxic phenol.

A sequencing batch reactor was used to investigate the effect of carbon sources on the metabolism of activated sludge. Acetate and phenol, with the chemical oxygen demand (COD) of 330-350 mg L(-1), was used as the carbon source in Periods I and II, respectively. Acetate decreased in the initial 120 min with the intracellular storage materials (XSTO), extracellular polymeric substances (EPS), and the soluble microbial products (SMP) accumulating to 131.0 mg L(-1), 347.5 mg L(-1), and 35.5 mg L(-1), respectively. Then, XSTO and EPS decreased to 124.5 mg L(-1) and 340.0 mg L(-1), respectively, in the following 120 min. When acetate was replaced by phenol, it could not be used at the beginning due to its toxicity. The XSTO decreased from 142 mg L(-1) to 54.6 mg L(-1) during the aeration period. The EPS had a significant increase, with the highest value of 618.1 mg L(-1), which then decreased to 245.6 mg L(-1) at 240 min. The phenol was gradually degraded with the acclimation and it can be fully degraded 18 d later. Meanwhile, the usage ratio of the internal carbon source decreased. The effluent SMP in Period II was 1.7 times that in Period I.

[The Study on the Characteristics of Organic Pollution in Typical Herbicide Plant Wastewater].

Herbicide wastewater is one of tne industrial wastewater, it has high salt content, poor biodegradability, biodegradable characteristics. Nitrogen-containing organic compounds are dominated in dissolved organic matter and dissolved organic matter of wastewater, BOD: COD = 0.045, C:N:P = 692:426:1. Applying static headspace, purg and trap, solid-phase extraction, solid-phase microextraction and liquid-liquid extraction as pretreatment methods combined with gas chromatography/mass spectrometry (GC/MS), which qualitatively analyzed the organic components of the Atrazine, acetochlor herbicide production wastewater and researched the UV spectrum, three-dimensional fluorescence spectroscopy of the wastewater and its major pollutants. The study of GC/MS indicated that Wastewater contained chlorinated hydrocarbons, BTEX and triazines, amides herbicides etc. 38 kinds of volatile and semi-volatile organic compounds, atrazine and acetochlor herbicides accounted for 87. 99%. Affected monocyclic or heterocyclic substances, the ultraviolet absorption spectrum of the wastewater in 210-230 and 250-270 nm in that the amino group lead to the UV absorption red shift 20 nm. Wastewater generated 5 fluorescence peak in λ(ex)/λ(em) = 200-280/300-400 nm, such as a(225/305 nm), b(265/365 nm), c(275/305 nm), d(285/390 nm), e(320/375 nm). Based on three-dimensional fluorescence results of the different functional groups of the characteristics organic, fluorescent area of unsaturated bond is in λ(ex)/λ(em) = 215-230/290-340 nm, the main contribution of the fluorescent substance in the region were olefins, benzene, heterocyclic in the wastewater; fluorescent area of Phenolic hydroxyl and carbonyl is in λ(ex)/λ(em) = 270/300 nm, the main contribution of the fluorescent substance in the region were phenols, ketones.

Bacteria morphology and diversity of the combined autotrophic nitritation and sulfur-carbon three-dimensional-electrode denitrification process.

The bacterial morphology and diversity in the reactors of a combined autotrophic nitritation and sulfur-carbon three-dimensional-electrode denitrification (CANSCTED) process operating under steady-state conditions were investigated by scanning electron microscopy and partial 16S rDNA cloning and sequencing. The CANSCTED process consisted of two parts, i.e., the nitritation membrane bioreactor (NMBR) and the sulfur-carbon three-dimensional-electrode denitrification reactor (SCTED). When the influent NH4(+) concentration of NMBR ranged from 854 to 1086 mg N L(-1), with about 50% NH4(+) removal efficiency and NO2(-) accumulation rate, the spherical and spheroidal ammonia-oxidizing bacteria were predominant, with community successions of ß-Proteobacteria (60.0%), Bacteroidetes (28.3%) and Chloroflexi (11.7%). The NMBR effluent with 429∼543 mg N L(-1) NH4(+) and 519∼578 mg N L(-1) NO2(-) was continuously supplied to SCTED for sulfur denitrification, bioelectrochemical hydrogen denitrification, and anaerobic ammonium oxidation. The predominant bacterial community successions were ß-Proteobacteria (78.3%) and ϵ-Proteobacteria (21.7%). When the SCTED influent was supplied with only NO2(-) (412-525 mg N L(-1)) as nitrogen substrate, the predominant bacteria in SCTED were short-bacilliform and spheroidal denitrification bacteria, ß-Proteobacteria (82.0%), ϵ-Proteobacteria (16.4%) and γ-Proteobacteria (1.6%). Although the predominant bacterial communities were both ß-Proteobacteria and ϵ-Proteobacteria in SCTED, the species and quantity of each community varied with the change of SCTED influent composition, which indicated that the composition influence the bacterial morphology and diversity in SCTED.

Passivation process and the mechanism of packing particles in the Fe0/GAC system during the treatment of ABS resin wastewater.

This study provides mechanistic insights into the passivation of the packing particles during the treatment of acrylonitrile-butadiene-styrene (ABS) resin wastewater by the Fe0/GAC system. The granular-activated carbon (GAC) and iron chippings (Fe0) were mixed together with a volumetric ratio of 1:1. GAC has a mean particle size of approximately 3-5 mm, a specific surface of 748 m2 g(-1), a total pore volume of 0.48 mL g(-1) and a bulk density of 0.49 g cm(-3). The iron chippings have a compact and non-porous surface morphology. The results show that the packing particles in the Fe0/GAC system would lose their activity because the removal of TOC and PO4(3-) for ABS resin wastewater could not carried out by the Fe0/GAC system after 40 days continuous running. Meanwhile, the availability of O2 and intrinsic reactivity of Fe0 play a key role on the form of passive film with different iron oxidation states. The passive film on the surface of iron chippings was formed by two phases: (a) local corrosion phase (0-20 d) and (b) co-precipitation phase (20-40 d), while that of GAC was mainly formed by the co-precipitation of corrosion products with SO4(2-) and PO4(3-) because SO4(2-) and PO4(3-) would not easily reach the Fe0 surface. Therefore, in order to avoid the occurrence of filler passivation, high concentrations of SO4(2-) and PO4(3-) in wastewater should be removed before the treatment process of the Fe/GAC system.

[Variation characteristics and removal rate of fluorescence organic matter in the petrochemical wastewater treatment process].

Petrochemical wastewater is of huge quantity released during the production and complicated contaminants of petrochemical wastewater will have immense negative impact on ecology environment. Three-dimensional excitation-emission matrix fluorescence(3D-EEM) was used to investigate the characteristic fluorescence of influent and effluent from each processing unit of Hydrolysis-acidification +A/O+ Contact-oxidation Process in a typical petrochemical wastewater treatment plant . The results showed that there were 4 fluorescence peaks named Peak A, Peak B, Peak D, Peak E in the spectrum chart of influent, they are around lambda(ex/lambda(em) = 220/300, 225/340, 270/300, 275/340 nm, the primary source of fluorescence organic matter(FOM) is industrial wastewater. The fluorescence intensity of each fluorescence peak was decreased, while location was unchanged in the effluent of Hydrolysis-acidification. Peak C appeared from the effluent of anaerobic tank at lambda(ex)/lambda(em) = 250/425 nm, then the fluorescence intensity of Peak C was enhanced in the effluent of aerobic tank. Peak A disappeared from the effluent of secondary sedimentation tank. The spectrum chart of the wastewater had no obvious variation after secondary sedimentation tank. The removal rate of FOM was expressed with the degradation percentage of the fluorescence intensity, the total FOM was reduced by 92.0% after processing, and the removal rate of the FOM fluoresce around Peak A, Peak B, Peak D, Peak E were 100.0%, 91.2%, 80.3%, 92.0% respectively. A volatile I(Peak B)/I(Peak E) value of influent but a relatively stable value of effluent demonstrated that the wastewater treatment plant operated steadily and the process has higher capacity in resistance to shock loading.

[A method for determination of trace naphthalene and phenanthrene in water using constant-wavelength synchronous fluorescence spectrometry].

In view of synchronous fluorescence possessing the character of good selectivity, high sensitivity, less interference, etc. it can be used for simultaneous determination of multi-component mixtures of polycyclic aromatic hydrocarbons (PAHs). A new method of constant-wavelength synchronous fluorescence spectrometry to determine two naphthalene and phenanthrene of PAHs was developed in this study. The effect of different experimental conditions, such as different disolvents for character of fluorescence spectra and the choose of the optimal wavelength difference were studied. Experiment showed that the simultaneous indentification and quantitative determination of the two PAHs when delta lambda = 100 was chosen. The fluorescence intensity was linearly related to naphthalene and phenanthrene concentration in the range of 0.5-25.0 microg x L(-1) with correlation coefficient 0.999 5 and 0.999 7, respectively. The detection limits were all lower than 0.03 microg x L(-1), and the relative standard deviations for naphthalene and phenanthrene were 1.19% and 180% (n=7), respectively. Results show that the compounds can be analyzed qualitatively and quantitatively by synchronous fluorescence spectrometry.

Enhanced denitrification of dispersed swine wastewater using Ca(OH)2-pretreated rice straw as a solid carbon source.

In a pilot-scale packed bed reactor, the denitrification performance and microbial community structure of the dispersed swine wastewater treatment using calcium hydroxide (Ca(OH)2) pretreated rice straw as a carbon source were investigated. In a Ca(OH)2-pretreated rice straw supported denitrification system (Ca(OH)2-RS), the removal efficiency of NO3--N was 96.39% at an influent NO3--N load of 0.04 kg/(m3•d). Meanwhile, there was no obvious accumulation of NO2--N or chemical oxygen demand (COD) in the effluent of Ca(OH)2-RS. The contents of soluble microbial byproduct-like substances and tryptophan-like substances in the effluent of Ca(OH)2-RS were reduced by 46.2% and 43.4%, respectively, compared with the influent. Overall, the Ca(OH)2-pretreated rice straw system had a strong resistance to fluctuations in water quality conditions, such as influent NO3--N and COD concentrations. According to the microbial assay results, the Ca(OH)2 pretreatment enriched more denitrifying bacteria. Among them, Proteobacteria (42.33%) and Bacteroidetes (35.28%) were the dominant bacteria. Moreover, the main denitrifying functional bacteria, generanorank_f_Saprospiraceae (13.32%), norank_f_Porphyromonadaceae (4.22%), and Flavobacterium (3.25%), were enriched in Ca(OH)2-RS. This suggested that using Ca(OH)2-pretreated rice straw as a carbon source was a stable and efficient technology to enhance the denitrification performance of dispersed swine wastewater.