Advanced Materials Research Vols. 1092-1093

Abstract: In order to establish a low cost and high efficiency immobilized microorganism system to treat Cr (VI) wastewater, the effects to removal capacity to Cr (VI) of microbe strain, additives and medium were investigated. These strains were immobilized with SA (sodium alginate) by immobilized microorganism technology combined with three additives CNTs (carbon nanotubes), activated carbon, straw and nutrient source, respectively. The results showed that three kinds of additives could improve the removal effect to Cr (VI), and the removal rate up to 30% when Cr (VI) concentration was 10mg/L. There was not a significant difference among these additives. The solution contains 40% medium could significantly improve the removal capacity to Cr (VI). The removal rate could reach more than 98% when Cr (VI) concentrations were 10mg/L-20mg/L. Therefore, efficient strains, additives and medium could improve the removal capacity to Cr (VI) of immobilized microorganism technology. It can be widely used in chromium contaminated wastewater.

Abstract: No.8 Bridge is the site where Yang River flows into Guanting Reservoir. It’s an important guarantee for the water safety of Guanting Reservoir that the water quality meets the standards steadily at No.8 Bridge. Based on the monitoring data from 2006 to 2013, the interannual and annual trends and correlations among DO, NH₃-N and COD of Yang River were analyzed. The factors affecting DO were also discussed. The results showed that DO and COD met the fourth-class standard for surface water. NH₃-N decreased year by year and its standard-reaching rate ran up to 70% since 2009. DO and COD, NH₃-N was negatively correlated, but not significant, indicating that COD and NH₃-N were not important factors affecting DO. DO varied along with seasons, autumn (mean 7.47mg /L) > spring (mean 7.35mg /L) > winter (mean 6.95mg /L) > summer (mean 6.35mg /L). Temperature is an important factor affecting DO. The possible impact on water environment of Guanting Reservoir caused by DO decrease should be paid special attention.

Abstract: Adsorptive biological reactive barrier comprising medium sand-bentonite-microorganism for removing simulated groundwater BTEX (benzene, toluene, ethyl benzene, xylene) of different concentrations has been investigated with the variance of filling media ratio, and the dependence of BTEX removal efficiency in groundwater on electron acceptor was also studied through adding nitrate. The results show that the optimum volume ratio of bentonite-medium sand is 20:80, with a permeable reactive barrier permeability coefficient of 2.01 × 10^-5 m/s and effective porosity of 16.71%. The addition of nitrate to biological reactive barrier stabilized BTEX removals under different concentrations, comparatively, while the control group without nitrate exhibited volatile BTEX removal efficiency. Under conditions of influent concentrations of 6, 8 and 10 mg/L, the BETX removal rates of biological reactive barrier with/without the addition of nitrate and the control group are about 94%/91%, 96%/90%, and 97%/87%, respectively. The adsorptive biological reactive barrier shows significant performance on BTEX removal, especially with the aid of nitrate additive.

Abstract: Land-based source of pollution is one of the main causes of pollution in the Bohai sea coastal waters, and drainage channel is the main contributor of Land-based source of pollution. Based on principal component analysis method for analysis of single factor evaluation method, selection principles for putting Tianjin Dagu river sewage pollution source location and determined the sample point, research history data and field monitoring of sewage and poisonous and harmful substances, determine a list of priority control pollutants and point pollution sources; Some corresponding land-based source of pollution control method and pollution prevention and control strategies was put forward in the paper.

Abstract: Chlorine-based or per-oxygen-based decontaminants could be used for destruction of cyanide ion in the emergency management of leakage. During destruction, poisonous gases like ClCN and HCN were often produced. It may lead to serious damage for personal safety and quality of environment. In this study, the amount of gaseous products of ClCN and HCN during destruction of KCN by hypochlorite solutions and peroxyl acid were first measured. And quantitative risks assessments correspond to different damage criterions were established. Results showed that toxic HCN gas would form once KCN aqueous exposed to atmosphere. And different decontaminants would result in different hazardous gasses. Chlorine-based decontaminants reacted with KCN would cause toxic gas of ClCN, and it lead to relatively larger depth of damage. It would cause medial lethal depth of damage under certain conditions, such as higher concentration of decontaminant, lower flow speed, higher temperature and large volume of KCN being destructed. For per-oxygen-based decontaminants, toxic HCN gas produced would cause relatively smaller depth of damage.

Abstract: Mercury is one of important trace heavy metal elements and about 1/3 of mercury in the air comes from emissions of coal-fired flue gas. In this study, we simulated mercury’s 4 important reactions of the oxidation kinetics mechanism and got every reactions’ rate variations; meanwhile we studied the kinetics of four reactions and got the reacting paths, five pre-exponential factor in different temperatures, reaction activation energy change and reaction rate constant change, a relatively comprehensive homogeneous oxidation model established. Through the above simulation study, the kinetics and thermodynamics parameters of 4 primitive reactions are obtained, having a great benefit for understanding the transformation mechanism of mercury in the process of coal combustion.

Abstract: A power plant of Datang Corporation in Hebei province is to reconstruct its wet flue gas desulfurization system. The power plant proposes three viable capacity extension schemes based on actual conditions: adding spray layers and increasing the height of the existing absorber, desulphurizing with series double-absorber and desulphurizing with dual-cycle double-absorber. This paper describes the technical characteristics of the schmes and compares their advantages and disadvantages based on performance, project investment and construction period. The result shows that the double-absorber scheme is more suitable for the power plant than the single-absorber scheme.

Abstract: The double membrane bio-reactor was used to treat the simulated wastewater under aerobic conditions, and the aerobic activated sludge system was set as the control. At the beginning of acclimation, COD removal efficiency in double membrane bio-reactor was higher than that of aerobic activated sludge system, but difference between two systems was little in later stage. The ammonia nitrogen removal rate in double membrane bio-reactor was significantly higher than aerobic activated sludge throughout the whole acclimation stage and nitrite concentration in the effluent from double membrane bio-reactor was lower than that of from aerobic activated sludge, while the nitrate concentration was higher. The nitrite was not accumulated in double membrane bio-reactor through the whole process of acclimation, while the accumulation of nitrate happened in aerobic activated sludge system.

Abstract: The silt content of inlet A, inlet flow B and underflow diameter C were the important factors on the separation efficiency of the hydrocyclone, using hydrocyclone for pretreatment of high turbidity silt water. The silt content of inlet selected 5 kg/m³, 4.5 kg/m³, 3 kg/m³, 2.5 kg/m³. Inlet flow rate selected 2.5 m³/h, 2.2 m³/h, 1.8 m³/h, 1.5 m³/h. The optimal solution selected B₂A₁C_2, which was 2.5 m³/h, 2.5 kg/m³ and 10 mm. The effects of various factors on the hydrocyclone separation were summarized objectively through the analysis of silt content of overflow and particle size. The result showed that: when the silt content of inlet was kept in a certain range, the medium diameter of overflow decreased to 18μm with the inlet flow rate increasing. Condensed bottle silt can discharged successfully, and the overflow water medium diameter decreased gradually with underflow diameter increasing.

Abstract: Using the mixed filling reaction column, this article examines that the influence of different inlet flow rate on the removal of nitrate nitrogen in groundwater, respectively by 90mL/h, 150 mL/h, 210mL/h velocity, under 30 °C each run five days, comparativly studies the influence of velocity on denitrification. The results show that the flow rate has an important effect on the denitrification of water, when the water inlet velocity decreased from 150mL/h to 90mL/h, the concentration of nitrate nitrogen reaction column effluent decreased gradually, and the denitrification of nitrite nitrogen accumulation system has been in a low level, but the ammonia nitrogen accumulation only in the flow rate of 90mL/h, began when the flow rate decreased significantly; also increased from 90mL/h to 210mL/h, the effluent nitrate nitrogen concentration, nitrite nitrogen concentration and ammonia nitrogen concentration increased significantly.