Intramolecular dehydrogenative C-S bond coupling of thioamides to form 1,3-benzothiazines under metal-free conditions.

A novel HTIB-promoted direct intramolecular dehydrogenative C-S bond coupling reaction of thioamides has been developed to provide 1,3-benzothiazine derivatives in good yields. The reaction proceeds smoothly to reach completion at room temperature within 1 min under metal-free conditions. This protocol provides a mild and efficient strategy for the synthesis of six-membered N,S-containing heterocycles. Preliminary mechanistic studies indicate that a spirocyclic intermediate might be involved.

Bacterial communities associated with an occurrence of colored water in an urban drinking water distribution system.

This study aimed to investigate bacterial community in an urban drinking water distribution system (DWDS) during an occurrence of colored water. Variation in the bacterial community diversity and structure was observed among the different waters, with the predominance of Proteobacteria. While Verrucomicrobia was also a major phylum group in colored water. Limnobacter was the major genus group in colored water, but Undibacterium predominated in normal tap water. The coexistence of Limnobacter as well as Sediminibacterium and Aquabacterium might contribute to the formation of colored water.

Changes in bacterial community of anthracene bioremediation in municipal solid waste composting soil.

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in a municipal solid waste (MSW) composting site. Knowledge of changes in microbial structure is useful to identify particular PAH degraders. However, the microbial community in the MSW composting soil and its change associated with prolonged exposure to PAHs and subsequent biodegradation remain largely unknown. In this study, anthracene was selected as a model compound. The bacterial community structure was investigated using terminal restriction fragment length polymorphism (TRFLP) and 16S rRNA gene clone library analysis. The two bimolecular tools revealed a large shift of bacterial community structure after anthracene amendment and subsequent biodegradation. Genera Methylophilus, Mesorhizobium, and Terrimonas had potential links to anthracene biodegradation, suggesting a consortium playing an active role.

Biosorption characteristics of ectomycorrhizal fungal mycelium for anthracene.

OBJECTIVE: To investigate the potential of Gomphidius viscidus, a kind of ectomycorrhizal fungi, for phytoremediation of anthracene in soil. METHODS: Absorptioe changes of micro-habitat were studied in detail. CONCLUSION: Ectomycorrhizal plants have a strong potential for remediation of polycyclic aromatic hydrocarn characteristics of both active and inactivated mycelia. RESULTS: A high calculated adsorption capacity of 1,886.79 mg/g and 1,515.15 mg/g at 25 °C, pH 6.0 for active and inactivated mycelia respectively, was obtained based on Langmuir model. The ANT biosorption was more ideally characterized by the Langmuir model than by the Freundlich model. The biosorption of anthracene to biomass was extremely fast and could be modeled with pseudo-second order adsorption kinetics. Moreover, ectomycorrhizal mycelia demonstrated a strong ability to adjust the physiological process to get adapted to the change of micro-habitat.

[Pilot experiment on the treatment of the river wastewater by a step-feed biological contact process].

In the Dianchi Lake watershed, the Daqinghe River with the highest load of pollution was chosen as the treatment target, a new step-feed biological contact (SFBC) process was studied to treat the wastewater from the riverway. The pilot experiment was carried out through a winter dry season, a spring dry season and a summer rainy season. The results showed that the SFBC process was well-adapted to the variation of the river wastewater qualities. By adjusting the process parameters in different seasons, the removal rates of COD and TP could be stable at about 50% and 40% respectively; however, the removal rate of TN was influenced by the water temperature and DO greatly, and kept at about 20% when the process went to its stabilization. Seeding with activated sludge could accelerate the start-up of the equipment, but the whole treatment efficiency was not as good as that of the equipment without seeding but domesticating the microorganism in the river wastewater. However, along with the running of the SFBC process as well as the impact of the influent sediment from the river, the difference of the treatment efficiencies between the two equipments of whether or not seeding with activated sludge would disappear gradually.

Control of bromate and THM precursors using ozonation combined system.

OBJECTIVE: To investigate the feasibility of reducing THM precursors and controlling bromate taste and odor in drinking water taken from the Yellow River by an ozonation combined system. METHODS: The appropriate ozone dosage was determined, and then the changes of TOC, UV254 and THM formation potential (THMFP) in the combined system were evaluated. RESULTS: One mg/L ozone could effectively remove taste and odor and meet the maximum allowable bromate level in drinking water. The pre-ozonation increased THMFP, but the conventional treatment system could effectively reduce the odor. The bio-ceramic filter could partly reduce CHCl3FP, but sometimes might increase CHCl2BrFP and CHClBr2FP. The biological activated carbon (BAC) filter could effectively reduce CHCl3FP and CHCl2BrFP, but increase CHClBr2FP. Compared with other filters, the fresh activated carbon (FAC) filter performed better in reducing THMFP and even reduced CHClBr2FP. CONCLUSION: The combined system can effectively reduce taste, odor, CHCl3FP, and CHCl2BrFP and also bring bromate under control.

Reduction of precursors of chlorination by-products in drinking water using fluidized-bed biofilm reactor at low temperature.

OBJECTIVE: To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). METHODS: Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3 degrees C, however, it could quickly rise to over 50% above 3degrees C. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

Biological pretreatment of Yellow River water.

Bio-ceramic filter(BF) and moving-bed biofilm reactor (MBBR) were used for biological pretreatment of Yellow River water in this study. The BF only had slight advantage over MBBR for TOC and ammonia removal. However, like UV254, the average removal rate of THMFP in the BF was much higher than that in the MBBR. UV254 removal did not show obvious correlation with trihalomethane formation potential (THMFP) removal. Hexachlorocyclohexane could be effectively removed in both BF and MBBR. As for diatom and cyanobateria removal the MBBR had better performance than the BF, which was contrary to the average chlorophyll-a ( Chl-a) removal rate. The proposal was made in this study that biological flocculation and sedimentation of sloughed biofilm should play a more important role on algae removal in the MBBR than in the BF. The BF and MBBR could effectively remove microcystins. Moreover, MBBR could be a promising technology for biological pretreatment.

[Treating of algae-laden raw water with GAC-sand dual media deep bed dissolved air flotation/filtration].

GAC-sand dual media deep bed dissolved air flotation/filtration (GSDDB-DAFF) is a new integrated process, its characteristics include: integration of dissolved air flotation and filtration, GAC-sand dual media deep bed filtration, integration of general treatment and advanced treatment. When algae-laden raw water was treated with the new process. The result showed that removal percentage of algae was 95.1%, outlet algae-count was 4.30 x 10(5) cell/L. Removal percentage of chlorophyll-a was 92.2%, outlet chlorophyll-a was 0.88 microg/L. Outlet turbidity was 0.18 NTU, removal percentage of UV254 was 54.3%, outlet UV254 was 0.016 cm(-1), Removal percentage of OC was 63.6%, outlet OC was 0.78 mg/L; outlet had no odor; removal percentage of color was 86.4%, outlet color was 3; outlet Al-residual was 0.011 mg/L which accorded with the quality standard of drinking water. Run time of filter was 36 h, UFRV (Unit Filter Run Volume) was 504 m3/m2.

Temperature effect on aerobic denitrification and nitrification.

Nitrogen loss without organic removal in biofilter was observed and its possible reason was explained. A lower hydraulic loading could improve aerobic denitrification rate. Aerobic denitrification was seriously affected by low temperature(below 10 degrees C). However, nitrification rate remained high when the temperature dropped from 15 degrees C to 5 degrees C . It seemed the autotrophic biofilm in BAF could alleviate the adverse effect of low temperature.