Thermodynamics of the interaction between antibiotics and extracellular polymeric substances within activated sludge.

The removal of antibiotics in biological wastewater treatment plants (WWTPs) has attracted an ever-increasing interest. Extracellular polymeric substances (EPS) play a crucial role in antibiotics' bio-adsorption using activated sludge, but the interaction mechanism between antibiotics and EPS remains unclear. In this study, the thermodynamics of interactions between EPS and antibiotics (acetaminophen (ACT) and sulfamethazine (SMZ)) were investigated via isothermal titration calorimetry (ITC). The results show that the extracellular proteins strongly combined with ACT and SMZ, and the binding process depended on entropy driven by the hydrophobic interaction as the main driving force. Environmental conditions have a significant impact on the adsorption performance. Therefore, binding of antibiotics and EPS at different pH and ionic strength were investigated to determine the optimal pH and ionic strength. At the near-neutral condition of pH 6.8, the binding reaction of EPS and antibiotics was the most favorable and the conformational change was the maximal. Ionic strength has an obvious effect on the interaction between EPS and antibiotics. The results of this study provided a better understanding of the interaction between antibiotics and EPS in the WWTPs.

[Effects of Gas/Water Ratio on the Characteristics of Nitrogen Removal and the Microbial Community in Post Solid-Phase Denitrification Biofilter Process].

To solve the problems of high-energy consumption, complex processes, and low nitrogen removal efficiency in the currently available low carbon source wastewater treatment processes, a novel coagulation sedimentation/post solid-phase denitrification biofilter process (CS-BAF-SPDB) was proposed. The effect of gas/water ratio on nitrogen removal efficiency of the CS-BAF-SPDB was studied. The changes in the microbial community structure along the varying gas/water ratio were investigated, and the functional bacteria were identified using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that, to realize favorable nitrifying and denitrifying performance simultaneously in the BAF-SPDB unit, the gas/water ratio of the BAF should be set at 4∶1. In addition, the influence of the macro operational parameters on the performance of the BAF and SPDB had a direct relationship with the dynamic changes in the micro microbial community. The influence of gas/water ratio on nitrification performance in the BAF was mainly embodied in the changes of composition, amount, and activity of ammonia-oxidizing bacteria Candidatus and Nitrospira defluvii and nitrite-oxidizing bacteria Nitrosomonas sp. Nm47, whereas that on denitrification performance in the SPDB was mainly embodied in the changes of composition and amount of solid carbon substrate degrading denitrifying bacteria Pseudomonas sp. and Myxobacterium AT3-03 and heterotrophic denitrifying bacteria Dechloromonas agitate, Comamonas granuli, and Rubrivivax gelatinosus.

[Microbiological Characteristics of a Post Solid-Phase Denitrification Biofilter Process].

To solve the problems of high energy consumption, complex process, and low nitrogen removal efficiency of the currently available low carbon source wastewater treatment processes, a novel coagulation sedimentation/post solid-phase denitrification biofilter process was proposed. Domestic wastewater with low carbon to nitrogen ratio was treated. The changes in the microbial community structure along the biofilters were studied and the functional bacteria were identified using the polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the microbial diversity and richness of the microorganisms increased from the bottom to the top along the nitrification filter, while in the denitrification filter, there parameters increased firstly and then decreased from the bottom to the top along the cylinder. A bigger population of nitrifying and denitrifying bacteria was observed at the top and the middle of the nitrification and denitrification biofilter, respectively. Moreover, Nitrosomonas sp. Nm47 and Candidatus Nitrospira defluvii were the predominant nitrifying bacteria in the nitrification biofilter, and Myxobacteria and Rubrivivas gelatinosus were the predominant denitrifying bacteria in the solid-phase denitrification biofilter.

Enhanced excess sludge hydrolysis and acidification in an activated sludge side-stream reactor process with single-stage sludge alkaline treatment: a pilot scale study.

A pilot-scale side-stream reactor process with single-stage sludge alkaline treatment was employed to systematically investigate characteristics of excess sludge hydrolysis and acidification with alkaline treatment and evaluate feasibility of recovering a carbon source (C-source) from excess sludge to enhance nutrient removal at ambient temperature. The resulting C-source and volatile fatty acid specific yields reached 349.19 mg chemical oxygen demand (COD)/g volatile suspended solids (VSS) d-1 and 121.3 mg COD/g VSS d-1, respectively, the process had excellent C-source recovery potential. The propionic-to-acetic acid ratio of the recovered C-source was 3.0 times that in the influent, which beneficially enhanced biological phosphorus removal. Large populations and varieties of hydrolytic acid producing bacteria cooperated with alkaline treatment to accelerate sludge hydrolysis and acidification. Physicochemical characteristics indicated that recovered C-source was derived primarily from extracellular polymeric substances hydrolysis rather than from cells disruption during alkaline treatment. This study showed that excess sludge as carbon source was successfully recycled by alkaline treatment in the process.

A grit separation module for inorganic matter removal from activated sludge: investigation on characteristics of split sludge from the module.

A grit separation module was developed to prevent the accumulation of inorganic solids in activated sludge systems, and it achieved effective separation of organic matter and inorganic solids. To provide technical and theoretical support for further comprehensive utilization of split sludge (underflow and overflow sludge from the separation module), the characteristics of split sludge were investigated. The settling and dewatering properties of the underflow sludge were excellent, and it had high inorganic matter content, whereas the overflow sludge had higher organic matter content. The most abundant inorganic constituent was SiO2 (59.34%), and SiO2, Al2O3, and Fe2O3 together accounted for 79.53% of the inorganic matter in the underflow sludge. The mass ratio of Fe2O3, CaO, and MgO to SiO2 and Al2O3 was 0.245 in the inorganic component of the underflow sludge. The underflow sludge had the beneficial characteristics of simple treatment and disposal, and it was suitable for use as a base raw material for ceramsite production. The overflow sludge with higher organic matter content was constantly returned from the separation module to the wastewater treatment system, gradually improving the volatile suspended solid/total suspended solid ratio of the activated sludge in the wastewater treatment system.

[Planktonic Algae's Distribution and Correlation with Dissolved Organic Matters' Fluorescence in the End of the Three Gorges Reservoir's Back Water Zone].

For researching the community structure, composition, and distribution of the planktonic algae in the Three Gorges Reservoir (TRG), especially, within TRG water levels' fluctuating, mpacting to water quality with the algae's growing, 6 sampling cites in the end of the TGR's back water zone, from Chaotianmen to Taihonggang Town, are chosen to monitor, at the sensitive stages time of algal bloom between March to May 2012, namely, water levels lowing from the highest impounding. The community's structure, composition, and distribution of the planktonic algae in the TGR, and the correlation of water quality parameters and DOM's fluorescence features with algae density, are obtained. According to the experimental results, blue algae fibre, chlorella, melosira, navicula are the dominated algae in the end of the TGR's back water zone, from Chaotianmen to Taihonggang Town, algae density are 0.40~0.56 × 10(6), 1.9~0.8 × 10(6), 0.36~0.25 × 10(6), 0.42~0.15 × 10(6) cells · L(-1) respectively. Besides, anabaena, phormidium, cladophora, feather, ovate algae are existing in only limited 2 sections. The fitting results reveal obvious linear correlation of the EEM characteristics of DOM with the 4 kinds of dominated algal density, which could be useful conference for the algae bloom monitor, conveniently and effectively.

Investigation into cyclic utilization of carbon source in an advanced sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal (SIPER) wastewater treatment process.

An advanced wastewater treatment process (SIPER) was developed to simultaneously reduce sludge production, prevent the accumulation of inorganic solids, recover phosphorus, and enhance nutrient removal. The ability to recover organic substance from excess sludge to enhance nutrient removal (especially nitrogen) and its performance as a C-source were evaluated in this study. The chemical oxygen demand/total nitrogen (COD/TN) and volatile fatty acids/total phosphorus (VFA/TP) ratios for the supernatant of the alkaline-treated sludge were 3.1 times and 2.7 times those of the influent, respectively. The biodegradability of the supernatant was much better than that of the influent. The system COD was increased by 91 mg/L, and nitrogen removal was improved by 19.6% (the removal rate for TN reached 80.4%) after the return of the alkaline-treated sludge as an internal C-source. The C-source recovered from the excess sludge was successfully used to enhance nitrogen removal. The internal C-source contributed 24.1% of the total C-source, and the cyclic utilization of the system C-source was achieved by recirculation of alkaline-treated sludge in the sludge reduction, inorganic solids separation, phosphorus recovery (SIPER) process.

[The Influence of Runoff Pollution to DOM Features in an Urban Wastewater Treatment Plant].

Combined with wastewater treatment process, the sewage in sunny and rainy day was collected from a wastewater treatment plant in Chongqing. Three-dimensional fluorescence spectra was used to investigate the characteristic fluorescence of dissolved organic matter (DOM). DOM dissolved organic carbon (DOC), chemical oxygen demand (COD), fluorescence index (ƒ450/500) and fluorescence intensity ratio γ (A, C) of fulvic acid in ultraviolet and visible region were used to analyze the impact of rain runoff pollution on sewage DOM. According to the experimental data, the DOM fluorescence fingerprints of this wastewater treatment plant were quite different from typical municipal sewage, and the main component was tryptophan with low excitation wavelength (Peak S), then the tryptophan with long wavelength excitation (Peak T) followed. A2/O process had an approximative degradation of the protein-like both in sunny day and rainy day, but had a better degradation of fulvic-like, DOC and COD in rainy day than that in sunny day. Morever, the fluorescence peaks got red-shifted after the biological treatment. The differences of DOM fluorescence fingerprint between sunny and rainy day were significant, the fluorescence center of UV fulvic (Peak A) in rainy day getting blue-shifted obviously, shifting from 240 - 248/390 - 440 to 240 - 250/370 - 400 nm. Although the DOM types in sunny and rainy day were the same, the source of fulvic got more complex by runoff and the component ratio of DOM also changed. Compared with the sunny day, the proportion of Peak S in DOM dereased by 10%, and the proportion of Peak A increased by 7% in rainy day.

Enhanced nitrogen and phosphorus removal by an advanced simultaneous sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal wastewater treatment process.

An advanced wastewater treatment process (SIPER) was developed to simultaneously decrease sludge production, prevent the accumulation of inorganic solids, recover phosphorus, and enhance nutrient removal. The feasibility of simultaneous enhanced nutrient removal along with sludge reduction as well as the potential for enhanced nutrient removal via this process were further evaluated. The results showed that the denitrification potential of the supernatant of alkaline-treated sludge was higher than that of the influent. The system COD and VFA were increased by 23.0% and 68.2%, respectively, after the return of alkaline-treated sludge as an internal C-source, and the internal C-source contributed 24.1% of the total C-source. A total of 74.5% of phosphorus from wastewater was recovered as a usable chemical crystalline product. The nitrogen and phosphorus removal were improved by 19.6% and 23.6%, respectively, after incorporation of the side-stream system. Sludge minimization and excellent nutrient removal were successfully coupled in the SIPER process.

Microbial and metabolic characterization of a denitrifying phosphorus-uptake/side stream phosphorus removal system for treating domestic sewage.

In this study, an advanced wastewater treatment process, the denitrifying phosphorus/side stream phosphorus removal system (DPR-Phostrip), was developed for the purpose of enhancing denitrifying phosphorus removal. The enrichment of denitrifying phosphorus-accumulating organisms (DPAOs) and the microbial community structure of DPR-Phostrip were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), and the metabolic activity of seed sludge and activated sludge collected after 55 days of operation were evaluated by Biolog™ analysis. This experimental study of DPR-Phostrip operation showed that nutrients were removed effectively, and denitrifying phosphorus removal was observed during the pre-anoxic period. PCR-DGGE analysis indicated that DPR-Phostrip supported DPAO growth while inhibiting PAOs and GAOs. The major dominant species in DPR-Phostrip were Bacteroidetes bacterium, Saprospiraceae bacterium, and Chloroflexi bacterium. Moreover, the functional diversity indices calculated on the basis of Biolog analysis indicated that DPR-Phostrip had almost no effect on microbial community diversity but was associated with a shift in the dominant species, which confirms the results of the PCR-DGGE analysis. The results for average well color development, calculated via Biolog analysis, showed that DPR-Phostrip had a little impact on the metabolic activity of sludge. Further principal component analysis suggested that the ability to utilize low-molecular-weight organic compounds was reduced in DPR-Phostrip.

Validation of accumulation models for inorganic suspended solids of different particle size in an activated sludge system.

In this study the effect of different particle sizes of inorganic suspended solids (ISS) on the ISS accumulation in an activated sludge system was investigated. The volume mean particle diameters (Dv) of ISS were 26, 73, 106, 165, and 210 µm. There are four fates of ISS in an activated sludge system: (1) suspending in the activated sludge, (2) depositing at the bottom of the reactors, (3) discharged from the reactors via excess sludge, and lastly (4) discharged from the reactors via effluent. The accumulated ISS in the bioreactor was unevenly distributed. Based on the accumulation proportion of ISS in bioreactor, an ISS accumulation model was established, from which the ISS accumulation concentration and the MLVSS/MLSS could be predicted. The proportion of ISS suspending in activated sludge was 0.22, 0.21, 0.042 and 0.031. The proportion of ISS depositing at the bottom of bioreactors was 0.31, 0.47, 0.75, 0.76 and 0.92.

[Ultraviolet-initiated synthesis and characterization of anionic polyacrylamide].

APAM was prepared under the action of composite initiator and UV irradiation, using acryl amide (AM), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and acrylic acid (AA) as raw materials. The paper studied the effect of proportion between monomers, monomer ratio, initiator concentration and other factors on intrinsic viscosity of the polymer, and optimized preparation conditions. The chemical structure and thermal stability of APAM were characterized by UV, FTIR, SEM and DTA-TGA respectively. The results showed that the APAM with the intrinsic viscosity 1.6 x 10(3) mL x g(-1) can prepared when the proportion between monomers was 70 : 10 : 10, the monomer ratio was 40%, initiator concentration was 0.20%, pH was 9 and the illumination time was 60 min.

[Simultaneous determination of heavy metals in waste and biogas slurry of scale farm by microwave digestion/inductively coupled plasma-mass spectrometry].

A new microwave digestion/inductively coupled plasma mass spectrometry (ICP-MS) for simultaneous determination of 8 heavy metals including Zn, Cu, As, Pb, Cd, Cr, Hg and Ni in wastes of scale hoggery from livestock parks in Chongqing and its biogas slurry after anaerobic digestion, with which an all round, fast analysis of multiple heavy metals in biogas slurry was realized. From the experiment, Zn, Cu, As, Pb, Cd, Cr, Hg, and Ni were the dominating heavy metals in biogas slurry. The linear correlation coefficients for the heavy metals were between 0.999 89 and 0.999 98, indicating a good linear correlation. The determination limits were between 0.79 and 25.0 ng x L(-1), recovery adding standard between 96.5% and 107.6%, RSD between 1.06% and 4.35%. These parameters revealed that the method has good precision and accuracy, which could be applied to the heavy metals detection in biogas slurry, and provide reference for its post-use.

[Combined application of multiple fluorescence in research on the degradation of fluoranthene by potassium ferrate].

The degradation of fluoranthene was researched by combined means of multiple fluorescence spectra, including emission, synchronous, excitation emission matrix (EEM), time-scan and photometry. The characteristics of the degradation and fluoranthene molecular changes within the degradation's process were also discussed according to the information about the degradation provided by all of the fluorescence spectra mentioned above. The equations of fluoranthene's degradation by potassium ferrate were obtained on the bases of fitting time-scan fluorescence curves at different time, and the degradation's kinetic was speculated accordingly. From the experimental results, multiple fluorescence data commonly reflected that it had same degradation rate at the same reaction time. t = 10 s, and the degradation rate is -55%, t = 25 s, -81%, t = 40 s, -91%. No new fluorescent characteristic was observed within every degradation' stage. The reaction stage during t < or = 20 s was crucial, in which the degradation process is closest to linear relationship. After this beginning stage, the linear relationship deviated gradually with the development of the degradation process. The degradation of fluoranthene by potassium ferrate was nearly in accord with the order of the first order reaction.

[A new method for the preparation of potassium ferrate and spectroscopic characterization].

Calcium hypochlorite was used as the raw material for preparation of the high purity potassium ferrate. The study includes the effects of reaction temperature, recrystallization temperature, reaction time, Ca(ClO)2 dosage, and the amount of calcium hypochlorite on the yield. It was determined that when the reaction temperature was 25 degrees C, recrystallization temperature 0 degree C and reaction time 40 min, the yield was more than 75%. The purity was detected by direct spectrophotometric method to be more than 92%. The product was characterized by infrated spectrum(IR), X-ray diffraction (XRD) and ultraviolet spectrum (UV) methods and proved to be potassium ferrate that was prepared by calcium hypochlorite as the raw material.

[Study of vibrational spectra of humic substance in soils from the three Gorges Reservoir Area].

The six typical different parts of soils and sediments along the bank of the Three Gorges Reservoir Area (TGRA) were collected, and the humic substance isolated from the six parts of the soils and sediments' samples was separated to humic acid and fulvic acid, purified, and characterized with the combination of the Raman and IR vibrational spectroscopic technologies after cool-dried separation; through assigning the vibrational peaks in each part of the Raman and IR spectra of each sample part, the vibrational characteristics of the structures and the groups that belonged to the molecules of the humic acids and the fulvic acids in the soils and sediments of the TGRA were obtained; the changing features of the groups and structures in the humic acid and the fulvic aicd's molecules from the different soils and sediments in the TGRA were discussed with the environmental impact factors such as soil humic degree, the conditions of different soils conference, using and/or cultivating models and water level fluctuations. From the experimental results, the vibrations about C-O, C-C, and poly-hydrogen bonds dominate in the structures and the groups of each part' humic substance; the active vibration numbers in the upstream are more than in the downstream; the soil's humic degree has great effect on the formation of the humic substances' structures in soil's humic substance; the soil used as agricultural cultivating mode showed higher humic degrees in the upstream parts of the TGRA. The effect of the water level's fluctuation on the formation of the humic acid and fulvic aicd in the sediments of the TGRA is not obvious in the short time.

[Study of the fluorescence characteristics of DOM from the Yangtze River and Jialing River around Chongqing's urban areas].

The fluorescence emission and excitation emission matrix (EEM) technologies were used to characterize the dissolved organic matter (DOM) in the water body of the Yangtze River and Jialing River around the Chongqing urban areas from April to August 2008. Concerning about the accidents of the Wenchuan's Earthquake in May and Tangjiashan Yansaihu's effects in June, and the high water period time in the summer in two months of July and August, from the EEM obtained from each sampling station and time, the composition, distribution and their changing features of the DOM in the two rivers were investigated as combined with the water samples' environmental parameters such as pH, DO, DOC with EEM's fingerprint features, f(450/500) etc; finally the bio-environment behavior effects of the three types of fluorescence peaks were elaborated, where humic-like, fulvic-like, and protein-like from the five sampling stations' EEMs during the five months were given detailed representation. From the experimental results obtained, the fluorescence peaks are mainly composed of two types of fluorophores: humic-like and protein-like in the two rivers around the Chongqing urban areas during the investigation in five months, the protein-like's peaks value in Jialing River is higher than the values in the Yangtze River, and all the fluorescence peaks in the two Rivers' water body decrease more or less after the two Rivers join in Chun Tan sampling station; the protein-like peak is notably higher after the "5 x 12" earthquake period time including May and June and high water period time, which mainly originated from terrestrial sources, but its intensities decreased observably while the water bodies of the two rivers joining together in the Chao Tianmen and Chun Tan's sampling station.

[The study of dimethoate by means of vibrational and surface enhanced Raman spectroscopy on Au/Ag core-shell nanoparticles].

The vibrational structure of dimethoate, with its solid state and saturated solutions at acidic and basic conditions, was characterized with combination of means of FTIR and FT-Raman vibrational spectroscopy technology, and the comprehensive information about the dimethoate molecular groups' vibrational features was obtained. The surface enhanced Raman scattering (SERS) spectra of dimethoate at different concentrations with different acidic and basic conditions, and adsorbed on the substrate's surface of the core-shell Au/Ag nanoparticles, were also obtained. The adsorption states of dimethoate's molecule on the substrate's surface of the core-shell Au/Ag nanoparticles and the effects by the different acid-base conditions were investigated, with speculation of the adsorption mechanism. From the results, v(as)(NH), v(as)(CH3), v(O=C-N), tau(O=C-N), v(P-O), v(P=S), v(C-C) and delta(P-O-C) are the characteristic peaks of inner dimethoate structure's vibrations; and the concentration range in which dimethoate could interact with core-shell Au/Ag nanoparticles fully is about 1.0 x 10(-3) mol * L(-1) both in acidic and basic conditions. Dimethoate's molecule interacts with SERS' substrate surface mainly through P-O-C, O=C-C, (S-CH2), P=S, and CH3 structures; and the effects of dimethoate's hydrolysis path in acidic and basic conditions on the adsorption are discussed, which give some good references for the research of organophosphorus pesticides' transformations in different environmental systems.

[Movement and transformation of heavy metals in water-sediment in water-level-fluctuating zone of Three Gorges Reservoir Area].

According to the off-season regulation model for Three Gorges Reservoir, the characteristic of movement and transformation of Cu, Pb, Cd and Cr in sediment of water-level-fluctuating zone of Three Gorge Reservoir Area was investigated. The results indicated that the chemical fraction composition characteristics of heavy metals are different. Cu mainly existed in organic/sulphidic fraction and residual fraction; Pb mainly existed in carbonates, Fe-Mn oxides and residual fraction; Cd mainly existed in carbonates and Fe-Mn oxides fraction; Cr mainly existed in residual fraction. In flood season, the exposure of sediment from river bottom to atmosphere caused the decrease of TOC, AVS and pH and increase of ORP, and lowered the amount of extractable heavy metals. Heavy metals have the tendency to release to water body. The migration rates of Cu, Pb, Cd and Cr were 30.50%, 26.10%, 33.50%, and 11.77% respectively, the migration ability of heavy metals followed: Cd > Cu > Pb > Cr. The contributions of extractable fractions of Cu, Pb, Cd and Cr to the migrated heavy metals were 77.15%, 86.09%, 94.86%, and 32.34% respectively, extractable fraction was the mainly part of the migrated heavy metals. The off-season regulation model for Three Gorges Reservoir lowered the ecological harm of heavy metals, the concentrations of Cu, Pb, Cr, Cd in the study areas were low.