Molecular insight of dissolved organic matter and chlorinated disinfection by-products in reclaimed water during chlorination with permanganate preoxidation.

Permanganate is a common preoxidant applied in water treatment to remove organic pollutants and to reduce the formation of disinfection by-products. However, the effect of permanganate preoxidation on the transformation of dissolved effluent organic matter (dEfOM) and on the formation of unknown chlorinated disinfection by-products (Cl-DBPs) during chlorination remains unknown at molecular level. In this work, the molecular changes of dEfOM during permanganate preoxidation and subsequent chlorination were characterized using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Permanganate preoxidation was found to decrease the DBE (double bond equivalent) and AImod (modified aromaticity index) of the dEfOM. The identity and fate of over 400 unknown Cl-DBPs during KMnO4-chlorine treatment were investigated. Most Cl-DBPs and the precursors were found to be highly unsaturated aliphatic and phenolic compounds. The Cl-DBPs precursors with lower H/C and lower O/C were preferentially removed by permanganate preoxidation. Additionally, permanganate preoxidation decreased the number of unknown Cl-DBPs by 30% and intensity of unknown Cl-DBPs by 25%. One-chlorine-containing DBPs were the major Cl-DBPs and had more CH2 groups and higher DBEw than Cl-DBPs containing two and three chlorine atoms. 60% of the Cl-DBPs formation was attributed to substitution reactions (i.e., +Cl-H, +2Cl-2H, +3Cl-3H, +ClO-H, +Cl2O3-2H). This work provides detailed molecular level information on the efficacy of permanganate preoxidation on the control of overall Cl-DBPs formation during chlorination.

Synergistic effects of ozone/peroxymonosulfate for isothiazolinone biocides degradation: Kinetics, synergistic performance and influencing factors.

Synergistic effects of ozone (O3) and peroxymonosulfate (PMS, HSO5-) for isothiazolinone biocides degradation was studied. The synergistic ozonation process (O3/PMS) increased the efficiency of methyl-isothiazolinone (MIT) and chloro-methyl-isothiazolinone (CMIT) degradation to 91.0% and 81.8%, respectively, within 90 s at pH 7.0. This is 30.6% and 62.5% higher than the corresponding ozonation efficiency, respectively. Total radical formation value (Rct,R) for the O3/PMS process was 24.6 times that of ozonation alone. Calculated second-order rate constants for the reactions between isothiazolinone biocides and (kSO4-,MIT and kSO4-,CMIT) were 8.15 × 109 and 4.49 × 109 M-1 s-1, respectively. Relative contributions of O3, hydroxyl radical (OH) and oxidation to MIT and CMIT removal were estimated, which were 15%, 45%, and 40% for O3, OH and oxidation to MIT, and 1%, 67%, and 32% for O3, OH and oxidation to CMIT at pH 7.0, respectively. Factors influencing the O3/PMS process, namely the solution pH, chloride ions (Cl-), and bicarbonate (HCO3-), were evaluated. Increasing the solution pH markedly accelerated O3 decay and OH and formation, thus weakening the relative contribution of O3 oxidation while enhancing that of OH and . Cl- had a negligible effect on MIT and CMIT degradation. Under the dual effect of bicarbonate (HCO3-) as inhibitor and promoter, low concentrations (1-2 mM) of bicarbonate weakly promoted MIT and CMIT degradation, while high concentrations (10-20 mM) induced strong inhibition. Lastly, oxidation performance of O3 and O3/PMS processes for MIT and CMIT degradation in different water matrices was compared.

Surrogates for on-line monitoring of the attenuation of trace organic contaminants during advanced oxidation processes for water reuse.

The large number of trace organic contaminants (TrOCs) in wastewater has resulted in severe concerns to human health. Ozonation and UV/H2O2 are widely used to remove TrOCs in wastewater treatment process. Owing to the trace concentrations of TrOCs in wastewater, real-time monitoring of the abatement efficiency of TrOCs through ozonation and UV/H2O2 is quite challenging. Instead of a direct measurement of all the TrOCs, the research community has begun to use different surrogates to monitor the attenuation of TrOCs during AOPs. Various surrogates have been developed over the past few decades. In this review, the different types of surrogates are summarized, including ultraviolet spectroscopy and fluorescence spectroscopy. Strong linear correlations have been found for the removal of TrOCs using AOPs, and the abatement of UV absorption spectroscopy at 254 nm or total fluorescence (TF). Moreover, a two-phase linear correlation can better describe the ozone-resistant TrOCs compared with a single linear correlation. Two different kinds of predictive models exist that use surrogates as the input for ozonation: the regression model and kinetic model. The development of the models requires a further understanding of the impacts of water quality, seasonal variations, and storm events on the kinetic parameters. For the in situ monitoring system, the light-emitting diode (LED) is one of the most promising light sources, although the sensitivity and accuracy still need to be improved.

[Speciation Distribution and Risk Assessment of Heavy Metals in Typical Material Roof Dusts].

With the modified BCR sequential extraction procedure, the chemical speciation and risk for 10 heavy metals (Ba, Co, Cr, Cu, Mn, Ni, Pb, Sb, Sr and Zn) in roof dusts were investigated. The subjects of this study were collected from four typical material paved roofs (i. e., ceramic tile, concrete, metal and asphalt) in southeast China. The results indicated that the average contents of heavy metals in roof dust significantly exceeded road dust. The analysis of chemical fraction showed that the acid soluble/exchangeable fraction of Zn was much higher than other elements, the existence of Pb and Cu was mainly in oxidization fraction, while other heavy metals dominated by the residual fraction. The mobility sequence percentages for all roof dust samples decreased in the order of Pb > Zn > Cu >>Mn > Co >>Sr > Sb > Ni > Ba > Cr, and it should be noted that Pb, Zn, Cu, Mn and Co all have more than 50% proportion in mobility sequence. Based on environmental risk assessment, the highest values of contamination factors (Cf) and risk assessment code (RAC) consistently was observed in Zn, which indicated that Zn had relatively high ecological risk. Health risk assessment showed that the non-carcinogenic hazard indexes (HI) of heavy metals decreased in the order of Pb > Cr > Sb > Zn > Mn > Cu > Ba > Ni > Co > Sr, the HI of heavy metals for adults were lower than safe value while the HI of Pb for children was higher than safe value, suggesting that they will not harm the adult's health except Pb for children. The carcinogenic risk for Cr, Co and Ni were all below the threshold values, which indicated that there was no carcinogenic risk.

[Nitrous oxide emission during denitrification for activated sludge acclimated with methanol as the organic carbon].

Denitrification of wastewater is one of the important sources of nitrous oxide (N2O). In this study, denitrifies were acclimated in a sequencing batch reactor with methanol and nitrate (NO3(-) -N) as the electron donor and acceptor, respectively. N2O emission during denitrification was examined both in typical cycles and in batch experiments under conditions of different electron acceptors, carbon/nitrogen (C/N) ratios and initial nitrite (NO2(-)-N) concentrations. With methanol as the organic carbon, the N2O emission was high with NO2(-)-N as the electron acceptor and the N2O emission was low with NO3(-) -N as the electron acceptor. The C/N ratios affected the emission of N2O by affecting activities of denitrifiers, and both the activity of denitrifiers and the emission of N2O decreased with decreasing C/N ratios. The N2O emission increased with increasing initial NO2(-) -N concentrations, and a certain range of NO2(-) -N concentrations enhanced the activity of denitrifiers. The N2O emission could be correlated very well with initial NO2(-) -N concentrations.

Several current-use, non-PBDE brominated flame retardants are highly bioaccumulative: evidence from field determined bioaccumulation factors.

With the phaseout of brominated flame retardants (BFRs) polybrominated diphenyl ethers (PBDEs), some non-PBDE BFRs have prompted to be alternatives to the discontinued PBDEs. To assess the bioaccumulation potential of these chemicals, field bioaccumulation factors (BAFs) for several non-PBDE BFRs including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB), were determined in the aquatic species from a natural pond in an electronic waste recycling site in South China. The log BAFs ranged 2.58-6.01, 3.24-5.58, 3.44-5.98, 2.85-5.98, 3.32-6.08, 2.04-4.77, 2.72-4.09 and 3.31-5.54 for α-HBCD, ß-HBCD, γ-HBCD, ∑HBCDs, BTBPE, PBT, PBEB, and HBB, respectively. The log BAF values for HBCD isomers, BTBPE, and HBB were greater than 3.7 (corresponding BAF value 5000) in most of the investigated species, demonstrating their highly bioaccumulative properties. α-, ß-, and γ-HBCDs, BTBPE, and HBB appeared comparable or had even greater BAFs compared to PBDE congeners with similar K(OW), suggesting that these BFRs may have a potentially high environmental risk. The BAFs for the given BFR compound were largely variable between species, due to the species-specific feeding ecology, trophic level, and metabolic capacity for these pollutants. Positive linear relationships between log BAF and log K(OW) (r² = 0.59, p = 0.04), and molecular weight (r² = 0.54, p = 0.06) of non-PBDE BFRs were observed in the species with low trophic level (Chinese mysterysnail), suggesting that the chemical's physicochemical properties also played key roles in the bioaccumulation processes.

Trophodynamics of hexabromocyclododecanes and several other non-PBDE brominated flame retardants in a freshwater food web.

Several currently used non-polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), and pentabromotoluene (PBT), are examined in the components of a freshwater food web from an electronic waste recycling site, South China. All these BFRs are detectable in the food web, with average concentrations of 13.9-868, 1.71-518, < 3.8-338, 197-3099, 3.98-25.6, and 1.20-3.60 ng/g lipid wt for HBCDs, BTBPE, DBDPE, HBB, PBEB, and PBT, respectively. Food web magnification is observed for (+)-alpha-, (-)-alpha-, (+/-)-alpha-, and total HBCDs, and HBB, with trophic magnification factors (TMFs) of 2.22, 2.18, 2.19, 1.82, and 1.46, respectively; whereas there is trophic dilution of BTBPE and PBT through the food web. The TMFs for (+)-alpha-, (-)-alpha-, and (+/-)-alpha-HBCDs are comparable to those of PBDEs detected previously in the same food web. Biota samples show a shift from gamma- toward alpha-HBCD compared with the suspended particles, sediment, and HBCD technical mixtures, with a significant increase of alpha-HBCD on ascending trophic levels. Except for alpha-HBCD in suspended particles and sediment, all the HBCD enantiomers detected are nonracemic in the environmental matrix. In biota, nonracemic residues of alpha-HBCD were observed in mud carp and crucian carp; beta-HBCD in prawn, mud carp, and crucian carp; and gamma-HBCD in water snake, with preferences for (+)-alpha-, (-)-beta-, and (+)-gamma-HBCDs.

Isomer-specific bioaccumulation and trophic transfer of Dechlorane Plus in the freshwater food web from a highly contaminated site, South China.

Dechlorane Plus (DP), a highly chlorinated flame retardant, has been detected in water, sediment, and aquatic organisms in a reservoir in the vicinity of electronic waste recycling workshops in South China. The biomagnification potential of DP in the food web was assessed and compared with that of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). DP was detected in all of the aquatic species, with concentrations of 19.1-9630 ng/g lipid wt. A depletion of anti-DP was observed in organisms compared with abiotic samples and the fraction of anti-DP was found to be further decreased upon moving up the trophic levels. This result suggested a stereospecific metabolism of anti-DP and/or isomer-selective uptake of syn-DP was occurring in organisms. Both syn- and anti-DP were significantly biomagnified in the present food web, with trophic magnification factors (TMFs) of 11.3 and 6.6, respectively. The trophic magnification potentials of the DP isomers were generally comparable to or lower than those of the highly recalcitrant PCB congeners in the same food web, but were 2-3 times greater than those of PBDE congeners.

Residues of polybrominated diphenyl ethers in frogs (Rana limnocharis) from a contaminated site, South China: tissue distribution, biomagnification, and maternal transfer.

Environmental pollutants are suspected to be a cause of global declines in amphibian populations, but few data are available on the bioaccumulation of polybrominated diphenyl ethers (PBDEs) in amphibians. To examine the tissue distribution, biomagnification potential, and maternal transfer of PBDEs in frogs, eighteen PBDE congeners were measured in the muscle, liver, and egg tissues of rice frogs (Rana limnocharis) and insects collected from an electronic waste (e-waste) recycling site in South China. PBDE levels in the frogs ranged from 0.63 to 11.6, 4.57 to 56.2, and 10.7 to 125 ng/g wet wt in the muscles, livers, and eggs, respectively. The frogs exhibited a unique congener profile, compared to those in aquatic and terrestrial species, with BDEs 99, 153, 183, 209, and 47 as the dominant congeners, intermediating between aquatic and terrestrial species. Most of the PBDE congeners in general showed higher affinity to liver than to muscle tissue. Except for BDEs 28, 47, 66, 138, and 206, the average biomagnification factors (BMFs) for all PBDE congeners were greater than 1.0, providing clear evidence of their biomagnification from insects to frogs. A parabolic relationship between log BMFs and bromine atom numbers or log Kow of PBDEs was observed, with the maximum BMF values for PBDEs with 6 bromine atoms (or at a log K(ow) of approximately 8.0). Relatively higher levels of 3-MeO-BDE 47 were found in male frogs, suggesting that male frogs in the present study might have higher metabolic capacity for PBDEs compared to female frogs. The ratio of levels in egg/female liver, indicating mother-to-egg transfer capacity, increased with increasing bromine atom numbers up to 7 and then declined as the bromine atom numbers rose. This indicated that the physicochemical properties of the congeners (e.g., K(ow), molecular sizes, and structures), resulting in different affinities to transport proteins, might impact their maternal transfer in frogs.

[Effect of biofilm on the corrosion and fouling of cast iron pipe for water supply].

The crystalline phase and the element composition in the scales on cast iron pipe for drinking water was identified with XRD and XPS respectively to investigate the effect of biofilm existence on the corrosion and fouling of cast iron pipe. The total iron concentration in the water phase was measured simultaneously. The results showed that on 0-7 d the total iron concentration was higher in the water phase of the group with biofilm growth, but on 15-30 d it was higher in the water phase of the control without biofilm growth. The major peak of XRD patterns for the scales with biofilm growth was characterized as Fe oxide, while for the scales in the control it was always characterized as CaCO3. As presented by XPS atomic ratio, the Ca atomic percentage in the scales with biofilm growth was lower than that in the scales in the control, which might be contributed to the Ca2+ absorption by extracellular polymeric substances or Ca2+ consumption by microorganism growth. In comparison with that in the scales in the control, the iron atomic percentage in the scales with biofilm growth was higher on 7 d, while lower after 7 d. It can be concluded that on 0-7 d the existence of biofilm could promote the corrosion of cast iron pipe while inhibit corrosion after 7 d. The variance of major peak of XRD pattern and XPS atomic ratio indicated that biofilm had important effect on the configuration and composition of the scales of cast iron pipe. The corrosion inhibition of biofilm thus provided a new pathway to control the corrosion of metal pipes in drinking water distribution system.

[Three-dimensional fluorescence fingerprint for source determination of dissolved organic matters in polluted river].

Fluorescence fingerprint technique was used to characterize dissolved organic matter (DOM) in river from different sources. The results showed that two types of DOM fluorescence signals were observed in river water: a humic-like fluorescence with three maxima at lambda(ex)/lambda(em) = 250/460 nm(A1), 220/400 nm(A2) and 325/420 nm(C); and a protein-like fluorescence with two maxima at lambda(ex)/lambda(em) = 230/360 nm(T2) and 285/357 nm(T1). The intensity of both of protein-like fluorescence distinctly increased because of the domestic wastewater drainage in the tributary stream. After the tributary converges into the main stream, the Fe3+ concentration in the main stream is 30 times as much as that of tributary stream, and the visible blue-shift of humic-like fluorescence occurred while the others didn't occur. The intensity of all types of fluorescence decreased from source to estuary resulting from different solute chemistry. However, the intensities of humic-like fluorescence C, A1 and protein-like fluorescence T2 at the longer excitation wavelength decreased significantly because of dilution from main river stream and complexation of humic-like with Fe3+, thus the peaks disappeared at the estuary while the fluorescence peaks at the shorter excitation wave-length were relatively stable on which the river solute chemistry had little effect. Therefore, the fluorophores at the shorter excitation wavelength of 220-230 nm area potential tool to determine the sources of DOM in polluted river.

[Pilot-scale study on riparian Scirpus yagara Ohw zone improving water quality of river].

In one year polluted water was treated with Scirpus yagara Ohw to investigate its impact on river water quality in pilot scale test, and COD, NH4(+) -N, TP, turbidity and water temperature were tested. The results show that the Scirpus yagara Ohw gives better water quality in summer and autumn than in winter and spring. In summer, the Scirpus yagara Ohw zone removes 44.10% of the COD, 78.66% of the ammonia, 69.44% of the phosphorous, and 99.53% of the turbidity. It also can improve water quality to some extent in winter. The Scirpus yagara Ohw can reduce effluent temperature and effluent temperature difference between evening and morning and then improve water microenvironment locally. Comparisons between the Scirpus yagara Ohw riparian zone and control zone showed that the Scirpus yagara Ohw affects importantly on removing pollutants, improving local microenvironment of water.

[Research on growth characteristic of Scirpus yagara Ohw and its decomposition on the riparian zone].

In order to understand growth of plant and its effect on ecological restoration of riparian zone, pilot-scale Scirpus yagara Ohw riparian zone had been studied for one year. Height and density of Scirpus yagara Ohw in different water depth showed that the water depth endurance of Scirpus yagara Ohw was not strong, and it growed and germinated better in shallow water. Contrast between harvest area and without harvest area showed that harvest was good for germination and growth of Scirpus yagara Ohw in next year. Distribution of biomass and N and P fixation between the underground and overground Scirpus yagara Ohw showed that N and P fixation of the underground was 50% and 126% more than that of the overground, respectively. Harvest of the overground Scirpus yagara Ohw can remove 40.5% of the total N and 30.6% of the total P. Dunked in water for 130 days, the overground Scirpus yagara Ohw lose 27.10% of its dry weight, 40.80% of the total N and 76.80% of tha total P. And the released pollutants have no serious cumulation in water.

[Pilot-scale study on riparian mixed plant zones treating polluted river water].

The polluted river water is treated with pilot-scale riparian zones of no aquatic plant, Vetiveria zizanioides + submerged plants, and weed+ Typha angustifolia L. + Phragmites communis. It is shown that the vegetation water zones are better than the no vegetation water zone and Vetiveria zizanioides + submerged plants zone is the best in improving water quality. The average removals of the Vetiveria zizanioides + submerged plant zone is 43.5% COD, 71.1% ammonia and 69.3% total phosphorus respectively. The dissolved oxygen (DO) and temperature of effluents from the three water zones are also investigated. It shows that DO of effluent from the vegetation zones are more stable than that of effluent from the no vegetation zone, and the temperature of the effluent from the vegetation zones are lower than that from the no vegetation zones. The submerged plants have special role in water quality improvement, and should be studied further.

[Effects of SRT and carbon concentration on the PHB in the anaerobic/aerobic alternative operating SBR process].

Effects of SRT and carbon concentration on the PHB of the anaerobic/aerobic SBR process are studied. The results show that by the order of SBR51,SBR10 and SBR52,the maximum PHB content of MLVSS were 9.8%, 5.72% and 18.89%, respectively, while carbon translating ratios were 46%, 34% and 36.3% during the first 20min of aerobic phase and PHB forming rate were 196.6mg/(L x h), 140mg/(L x h) and 295.35mg/(L x h). PHB degradation rate can be described with a first order degradation rate with respect to the PHB content of the cells. Reclamation of PHB should consider from several factors. Carbon concentration gradient is the main factor influencing PHB formation under batch experiment.

[Study on the animal model for severe acute respiratory syndrome].

To screen small animals susceptible to SARS-CoV, five species of animals, including guinea pig, hamster, albino hamster, chicken and rat, were experimentally infected with SARS-CoV strain BJ-01 by different routes. On the basis of this, further cynomolgus and rhesus macaques were selected and experimentally inoculated SARS-CoV, the quality they serve as animal model for SARS was evaluated. The results showed that, all five species of small animals chosed were not susceptible to SARS-CoV, no characterized changes in clinical sign and histopathology were observed after infection, but from the lung samples of large rat and pig guinea, the genomic RNA of SARS-CoV could be detected by RT-PCR at day 14 post infection, this suggested that SARS-CoV could replicate in these animals. After inoculated with SARS-CoV, all inoculated cynomolgus and rhesus macaques had developed interstitial pneumonia of differing severity. These changes on histopathology were similar to that seen in SARS patients, but the pathological lesions were less severe than that of human. Except interstitial pneumonia, no other characterized pathological changes were observed. This suggested cynomolgus and rhesus macaques were not the ideal animal model for SARS in fact, but they could serve as animal model for SARS when a more ideal animal model is absent.

[Effect of carbon and nitrogen sources on the accumulation of poly-beta-hydroxybutyrate by purple non-sulfur photosynthetic bacteria].

The effect of carbon and nitrogen sources on the accumulation of Poly-beta-Hydroxybutyrate (PHB) by purple non-sulfur photosynthetic bacteria (PNSB)was investigated. The results showed that ammonia nitrogen and organic nitrogen could benefit the PNSB accumulating PHB; under certain ratio of carbon and nitrogen low carbon concentration can accumulate more PHB, but high carbon concentration is better for PNSB accumulating PHB with the growth of PNSB. As to different substrates, butyrate is the best for accumulating of PHB, but acetate is better and propionate is the poorest. Mixed substrate with butyrate as the main content are better than single substrate; carbon dioxide have certain effect on the PNSB accumulating PHB, and high carbon dioxide concentration can improve PHB content when using acetate or butyrate as substrate.