[Mechanism of Pre-ozonation Enhanced Coagulation on DON in the Secondary Effluent].

Municipal wastewater effluent is increasingly used as reclaimed water and source water for downstream areas. Scholars are beginning to study the potential of dissolved organic nitrogen (DON) as a precursor to the formation of nitrogen disinfection by-products (DBP). In order to explore the mechanism of pre-ozonation coupled with enhanced coagulation on DON in the secondary effluent, the distributions of molecular weight and hydrophobicity/hydrophilicity of DON were analyzed. Disinfection by-product formation potential from chlorination was also investigated. Lastly, the composition and chemical structure of DON before and after coagulation were studied in combination with 3DEEM. Our results showed that pre-ozonation followed by coagulation with PACl significantly enhanced the removal of DON and mitigated DBP formation potentials. The following conclusions can be drawn from this study:① The tested effluent was very hard as indicated by total hardness and high calcium concentrations, and the pH had an important effect on pre-ozonation enhanced coagulation. As pH was decreased, the rates of DON, DOC and UV254 removal increased. At pH 6.2, the rate of DON removal was maximal, and a 3.7 fold increase in removal-rate was achieved. ② Calcium played a critical role in pre-ozonation enhanced coagulation. Zeta potentials and calcium concentrations were substantially affected at higher ozone doses. At ozone dosage of 8 mg·L-1, Zeta potentials increased from -33 to -8 mV, and calcium concentrations decreased from 116 to 89 mg·L-1. The ratio of calcium hardness to DOC was relatively high in this study, approaching 24 mg·mg-1 (CaCO3/DOC). Thus, pre-ozonation promoted the removal of DON by coagulation. ③ Large molecular weight and hydrophobic DON were easier to remove by coagulation. Ozonation modified the DON characteristics to become more hydrophilic and smaller in molecular weight. Coagulation reduced overall DBP formation potentials to less than 20%. Pre-ozonation enhanced coagulation decreased overall DBP formation potentials by more than 45%. ④ Finally, the 3DEEM spectra indicated that the formation potentials and DON characteristics, due to disinfection, were related to three main peaks, which corresponded to tryptophan-based proteins, aromatic proteins, and fulvic acids.

[Chlorination characteristic and disinfection by-product formation potential of dissolved organic nitrogen compounds in municipal wastewater].

In order to explore the chlorinated disinfection by-product formation potential and chemical structure of dissolved organic nitrogen compounds in municipal wastewater, the water quality parameters, such as DON, DOC, NH4(+) -N and UV254 etc, were determined in the secondary effluent and the molecular weight distribution of the DON was investigated before and after the reaction with chlorine. DBPs were determined by gas chromatography, and the changes of DON were characterized using Fourier transform infrared spectroscopy and three-dimensional fluorescence spectroscopy before and after the reaction with chlorine. The results showed that DON, DOC, NH4(+) -N and UV254 were 2.47 mg x L(-1), 14.45 mg x L(-1), 5.42 mg x L(-1) and 15.88 m(-1), and m(DOC)/m(DON) and SUVA were 5.85 mg x mg(-1) and 1.09 L x (m x mg)(-1) in the secondary effluent. After the reaction with chlorine, the proportion of small molecular weight (M(r) < 6 000) DON increased from 78% to 70% , and the proportion of large molecular weight (M(r) > 20 000) DON decreased from 21% to 14%. The medium molecular weight (M(r)6000-20000) DON accounted for a small proportion and was unchanged. Among the DBPs, the concentration of bromochloroacetonitrile was the highest, which was 6.887 microg x L(-1), and the concentration of trichloroacetonitrile was the lowest, which was only 0.217 microg x L(-1). In FTIR spectrum, the dominating bands were at 3 500-3 400, 2 260-2 200, 1 700-1 640, 1 500-1 450, 1 150-1 100 and 850-800 cm(-1) respectively before the reaction, and the 1 380-1 350 cm(-1) and 600-550 cm(-1) bands were the dominating bands in addition to the original absorbing regions after the reaction. 3DEEM revealed that the variation of DON depends intimately on tryptophan protein-like substances, aromatic protein-like substances and fulvic acid-like substances.

[Removal of DON in micro-polluted raw water by coagulation and adsorption using activated carbon].

Dissolved organic nitrogen as a precursor of new type nitrogenous disinfection by-products in drinking water attracted gradually the attention of scholars all over the world. In order to explore the mechanism of DON removal in micro-polluted raw water by coagulation and adsorption, water quality parameters, such as DON, DOC, NH4(+) -N, UV254, pH and dissolved oxygen, were determined in raw water and the molecular weight distribution of the DON and DOC was investigated. The variations in DON, DOC and UV254 in the coagulation and adsorption tests were investigated, and the changes of DON in raw water were characterized using three-dimensional fluorescence spectroscopy. The results showed that DON, DOC and UV254 were 1.28 mg x L(-1), 8.56 mg x L(-1), 0.16 cm(-1), and DOC/DON and SUVA were 6.69 mg x mg(-1), 1.87 m(-1) x (mg x L(-1))(-1) in raw water, respectively. The molecular weight distribution of the DON in raw water showed a bimodal distribution. The small molecular weight (< 6 000) fractions accounted for a high proportion of 68% and the large (> 20 000) fractions accounted for about 22%. The removal of DON, DOC and UV254 was about 20%, 26% and 70%, respectively, in the coagulation test and the dosage of coagulant was 10 mg x L(-1). The removal of DON, DOC and UV254 was about 60%, 35% and 100%, respectively, in the adsorption test and the dosage of activated carbon was 1.0 g. In the combination of coagulation and adsorption, the removal of DON and DOC reached approximately 82% and 64%, respectively. 3DEEM revealed that the variation of DON in the coagulation and adsorption tests depended intimately on tryptophan protein-like substances, aromatic protein-like substances and fulvic acid-like substances.

[Mechanism of NH(4+)-N removal in drinking water biofilter].

In order to explore the mechanism of NH(4+)-N removal in drinking water biofilter, water quality parameters, such as NH(4+)-N, NO(2-)-N, NO(3-)-N, total phosphorus, permanganate index, nitrogen gas, temperature and dissolved oxygen etc, were determined in the inflow and outflow of biofilter. Samples of granular activated carbon (GAC) at different height (0, 10, 20, 40, 60 cm) of the biofiter media were collected and analyzed for the bacterial community with molecular biology techniques. The bacterial diversity in the activated carbon biofilm sample was studied based on the phylogenetic analysis of sequences. The results showed that there were three stages according to the NH(4+)-N concentration in the influent. The "nitrogen loss" phenomenon (total inorganic nitrogen in the effluent was less than that in the influent) occurred at the first, second and third stages and the amount of nitrogen loss were 0.94, 0.32 and 0.15 mg x L(-1), respectively. The amount of nitrogen loss had a good positive correlation with the NH(4+)-N concentration in the influent, but not a linear relationship with the concentration of the permanganate index in the influent. The average concentrations of N2 increased gradually with the height of media in the biofilter, with values of 14.04 and 14.67 mg x L(-1) in the influent and the effluent, respectively. Based on the sequencing results, the ammonia-oxidizing bacteria (AOB) in the activated carbon biofilm were classified into three common genera: Nitrosococcus, Nitrosomonas and Nitrosospira. When the NH(4+)-N concentration in the influent was relatively high, the "nitrogen loss" phenomenon in biofilter was caused by the AOB.

[The standardized practice of laparoscopic-assisted radical right hemicolectomy in order to achieve complete mesocolic excision].

OBJECTIVE: To explore the feasibility of laparoscopic-assisted radical right hemicolectomy with the outcome being a complete mesocolic excision (CME). METHODS: Between February 2010 and June 2011, we performed the standardized surgery of laparoscopic-assisted radical right hemicolectomy with an aim of CME on 14 patients. There were 10 males and 4 females, with an average age of 57 years (range 36 to 74 years). All the pathologic results in 14 cases were primary colonic adenocarcinoma. The TNM stages were distributed as follows: 2 in II A, 3 in II B, 3 in III A, 5 in III B and 1 in III C. RESULTS: Surgery was successfully performed for all patients without open conversion. The average operation time was (178 ± 37) minutes (range 127 to 221 minutes), average intraoperative blood loss was (67 ± 23) ml (range 30 to 110 ml), while the average number of lymph node harvest was 21 ± 7 (range 14 to 31), and the postoperative hospital stay was (10.0 ± 2.2) days (range 7 to 15 days). Minor complications occured in 2 patients. Major complications and post-operative mortality were not observed. All the patients were followed up for 3 to 19 months, no tumor recurrence or metastasis was identified. CONCLUSION: The standardized surgery of laparoscopic-assisted radical right hemicolectomy with the final outcome of CME is safe and feasible.

[Removing breast foreign body resulted from augmentation with polyacrylamide hydrogel injection and silicone prosthesis implantation at one stage].

OBJECTIVE: This study was to investigate an operation, in which removing breast cysts of foreign body resulted from augmentation with polyacrylamide hydrogel injection was performed simultaneously with silicone prosthesis implantation under SEPS endoscope in order to relieve tissue injury and increase the accuracy of clearance. METHODS: Eight patients were included in this study. Preoperative type B ultrasound examination was performed to mark the mass. Through an axillary approach, the cysts of foreign body that were distributed in the subcutaneous tissue, breast or muscle were separated and ablated under SEPS endoscope. After removal of the foreign body, a silicone implant was located submuscularly for breast augmentation. RESULTS: The operations were completed without hematoma and infection. Follow-up of the eight patients for 3 to 12 months showed that preoperative symptoms relating to the injected material, such as breast pain, lump and asymmetry, have no longer existed. The shapes of the breasts were satisfactory. CONCLUSIONS: We believe that endoscope-assisted mammoplasty offers more satisfactory clinical results with less injury, less morbidity, less scars, more accuracy and greater patient acceptance.

Phosphorus limitation on bacterial regrowth in drinking water.

Assimilable organic carbon (AOC) test and bacterial regrowth potential (BRP) analysis were used to investigate the effect of phosphorus on bacterial regrowth in the drinking water that was made from some raw water taken from a reservoir located in northern China. It was shown that AOC of the drinking water samples increased by 43.9%-59.6% and BRP increased by 100%-235% when 50 microg/L PO4(3-)-P(as NaH2 PO4) was added alone to the drinking water samples. This result was clear evidence of phosphorus limitation on bacteria regrowth in the drinking water. This investigation indicated the importance of phosphorus in ensuring biological stability of drinking water and offered a novel possible option to restrict microbial regrowth in drinking water distribution system by applying appropriate technologies to remove phosphorus efficiently from drinking water in China.

Effect of daily dosing duration of direct and indirect dopamine receptor agonists: cocaine cross-tolerance following chronic regimens.

One therapeutic paradigm for cocaine abuse is a 24-h 'agonist' treatment which reduces reinforcing effects in a manner similar to the methadone maintenance model for heroin. However, 24-h dosing of dopamine (DA) agonists may induce side effects of insomnia and psychosis, as well as anergia and anhedonia which may actually potentiate abuse. Thus, it is important to determine the daily dose duration of potential treatments such as direct (e.g. pramipexole) and indirect (e.g. GBR 12909) DA agonists, that may induce cross-tolerance with cocaine. We gave a cocaine challenge (15 mg/kg i.p.) on withdrawal day 7 and recorded ambulations and a behavioral rating. We found that 20- and 24-, but not 16-h, daily dosing with cocaine (40 mg/kg), for 14 days, induced tolerance. Pramipexole (4 mg/kg), administered for 24 but not 12 h per day, for 14 days, induced cocaine cross-tolerance while GBR 12909 (18 mg/kg), administered i.p. over 24 or 16 h a day, for 7 days, did not. Thus daily dosing duration is an important variable in consideration of stimulant abuse treatment.