[Distribution model of aluminum species in drinking water basing on the reaction kinetics].

The effects of excess aluminum on water distribution system and human health were mainly attributable to the presences of some aluminum species in drinking water. A prediction model for the concentrations of aluminum species was developed using three-layer front feedback artificial neural network method. Results showed that the reaction rates of both inorganic monomeric aluminum and soluble aluminum varied with reaction time and water quality parameters, such as water temperature, pH, total aluminum, fluoride, phosphate and silicate. Their reaction orders were both three. The reaction kinetic parameters of inorganic monomeric aluminum and soluble aluminum could be predicted effectively applying artificial neural network; the correlation coefficients of k and 1/C0(2) between calculated value and predicted value were both greater than 0.999. Aluminum species prediction results in the drinking water of City M showed that when the concentration of total aluminum was less than 0.05 mg x L(-1), the relative prediction error was large for inorganic monomeric aluminum. When the concentration of total aluminum was above 0.05 mg x L(-1), the model could predict inorganic monomeric aluminum and soluble aluminum concentrations effectively, with relative prediction errors of +/- 15% and +/- 10% respectively.

[Effects of temperature and pH on the distribution of aluminum species in drinking water].

The effects of aluminum on water distribution system and human health are mainly attributable to their presence in drinking water. Laboratory experiments were performed to investigate the influence of temperature and pH on the distribution of aluminum species applying alum synthetic water. Aluminum species studied in the experiments included monomeric aluminum, soluble aluminum, suspended aluminum, and polymeric aluminum, which were determined by fluorescence spectrophotometry method. Results indicated that suspended aluminum was the major species at pH 6.5, occupied about 62.2% in the total aluminum mass concentration. While at pH above 7.0, monomeric aluminum was the major species; and varied little as reaction time increased. Polymeric aluminum mass concentration was low at studied water quality condition and also varied little as reaction time increased. The influence of temperature on aluminum species distribution was similar to solution pH; and both could be explained by pOH. Aluminum species in drinking water could be controlled by adjusting the pOH value, which provided theoretical guidance for the operation of the water distribution system and aluminum toxicity control.

[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.

[Al species distribution survey in portable water distribution system in a north city of China].

The residual Al concentration and species distribution of a north Chinese city was surveyed using fluorimetry. Results showed that the highest total Al concentration was 0.078 mg x L(-1) and the mean concentration was 0.038 mg x L(-1), lower than the latest portable water standard of 0.2 mg x L(-1). Inorganic mono-aluminum and inorganic poly-aluminum, the main toxicity-leading species, were also the major existence species with the mean concentration 0.011 mg x L(-1) and 0.013 mg x L(-1) respectively. While organic combined aluminum concentration was quite low. Correlation analysis results showed that the Al concentration and species distribution in a certain pipe line was connected with the water quality. When the distribution system contained more salts and less soluble organic matter, the Al concentration would be controlled in a low level, which was important to guide the local operation.

[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.

Pretreatment of apramycin wastewater by catalytic wet air oxidation.

The pretreatment technology of wet air oxidation (WAO) and coagulation and acidic hydrolysis for apramycin wastewater was investigated in this paper. The COD, apramycin, NH4+ concentration, and the ratio of BOD5/COD were analyzed, and the color and odor of the effluent were observed. WAO of apramycin wastewater, without catalyst and with RuO2/Al2O3 and RuO2-CeO2/Al2O3 catalysts, was carried out at degradation temperature of 200 degrees C and the total pressure of 4 MPa in a 1 L batch reactor. The result showed that the apramycin removals were respectively 50.2% and 55.0%, COD removals were 40.0% and 46.0%, and the ratio of BOD5/COD was increased to 0.49 and 0.54 with RuO2/Al2O3 and RuO2-CeO2/Al2O3 catalysts in catylytic wet air oxidation (CWAO) after the reaction of 150 min. With the pretreatment of coagulation and acidic hydrolysis, COD and apramycin removals were slight decreased, and the ratio of BOD5/COD was increased to 0.45, and the effluents was not suitable to biological treatment. The color and odor of the wastewater were effectively controlled and the reaction time was obviously shortened with WAO. HO2 may promote organic compounds oxidized in WAO of the apramycin wastewater. The addition of CeO2 could promote the activity and stability of RuO2/Al2O3 in WAO of apramycin wastewater.

[Study of photoelectrocatalytic oxidation of benzoic acid].

This study reports the photoelectrocatalytic oxidation of benzoic acid in a three-electrode photoelectroreactor. The effects of the anode bias potential, the atmosphere of reaction and the basis material for photocatalyst preparation on the removal efficiency of benzoic acid were researched. The photoelectrocatalysis was compared with photolysis, photocatalysis and electrolysis. The results of the experiments indicated the removal efficiency of benzoic acid after the photoelectrocatalytic oxidation process for 1 h could be more than 85%, much higher than the efficiency of photolysis (48%), photocatalysis (30%) and electrolysis (nearly having no effect). The synergetic effect of the photoelectricity was obvious. The working electrode and the counter electrode were arranged as two concentric columns whose diameters were different. The results showed that this kind of arrangement mode was very effective. In nitrogen atmosphere the removal efficiency of benzoic acid could be 98% when TiO2/Ti acted as the anode of the photoelectrocatalytic oxidation process for 1 h, much better than the TiO2/Al did (85%). While in oxygen atmosphere the two kinds of electrodes were both effective and the removal efficiency of benzoic acid could approach 100%.

[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.