Applied Mechanics and Materials Vols. 253-255

Abstract: Based on the pilot experiment on quick start-up of filter for removing manganese, amplification experiment was carried out. High concentration aeration and low concentration running were used in this experiment as starting mode. The maturity period of the filter for manganese removal is 9 days. Through the research on the distribution of manganese ions in filter bed by different filtration rate, the result shows a bigger depth of the filter bed is needed with the increase of filtration rate. For raw water with manganese ions concentration of 1.0-1.5 mg•L-1, the highest flow rate that can be handled by this equipment is 0.7 m•h-1. The blockages in filter bed can be washed out under the condition that the back washing intensity is 7.81 L•s-1•m-2 and the back washing time is 5 min. The back washing period of the filter is 13 days.

Abstract: An overview of characteristics and existence status of industrial wastes such as fly ash, coal gangue, red mud and pyrite cinder. The research progress of the preparation of wastewater treatment coagulants from industrial wastes has been introduced in detail. And some existing problems of the preparation of coagulants from industrial wastes have been pointed out, the solutions have been put forward.

Abstract: Lake eutrophication and algal bloom is one of the most important environmental problems facing China's lakes, and it is also the focus of lake eutrophication control of the world's attention. The monitoring data on chlorophyll concentration was analyzed every one month, combined with corresponding weather conditions from 2004 to 2006. According to the degree of eutrophication in Taihu Lake, it is divided into five Lakes: heavy eutrophication region V, eutrophication region IV, middle-level eutrophication region III, light eutrophication region II and nutrition region I. Based on fuzzy factor optimization method, the average wind speed, average pressure, average temperature and sunshine hours was selected to discuss the influence mechanism of meteorological factors on the algae bloom in Taihu Lake. Considered the four meteorological factors as the input layer nodes, BP neural network model was applied to build the zoning monitoring and early warning model of blue algae in Taihu Lake.

Abstract: Fulvic acid-modified vermiculite (FA-Ver) was prepared by mixing vermiculite and fulvic acid in a suspension. The XRD patterns showed that the vermiculite in FA-Ver possesses an irregular stacking of layers supported and non-supported by fulvic acid particles. The specific surface area (SSA), cation exchange capacity (CEC), pH at zero point of charge (pHZPC), and surface charge at pH 6.0 of FA-Ver was 379.35 m2/g, 52.17 cmol/kg, pH 2.36, and -0.442 mmol/g, respectively. The SSA, CEC and surface negative charge of FA-Ver increased and the pHZPC decreased compared to the corresponding values of vermiculite. Langmuir and Freundlich isotherms fitted the adsorption data for Pb(II) by HA-vermiculite well (R2=0.988 and 0.982, respectively). The Freundlich correlation coefficient of vermiculite was low (R2=0.954) and that of FA-Ver was slightly higher (R2=0.980). At pH 6.0, the Langmuir maximum adsorption capacities for Pb(II) of vermiculite and FA-Ver were 11.86 and 19.41 mg/g, respectively.

Abstract: A comparative study of three kinds of electrolysis methods: indirect electro-oxidation, electro-flocculation and electro-Fenton, as pre-treatment processes for a real dyestuff wastewater with high salinity and unbiodegradable organics were investigated. The efficiency of each method was evaluated according to the reduction levels of COD and toxicity, as well as biodegradability improvement. The results indicate electro-Fenton process as the most efficient pre-treatment method for improving biodegradability, reducing toxicity, and removing organic pollutants from dyestuff wastewater.

Abstract: Basing on the cost data of the wastewater treatment plant (WWTP) in Tianjin, the construction, operation and management cost was calculated. A regression model was developed considering the discount, and the average cost of sewage treatment was calculated. Three price policies were put forward, and the influence of the policies was simulated with the model. The results are powerful tools for government to pricing the wastewater treatment fee

Abstract: The removal of Cu2+ in water via an ion-exchange membrane under no external voltage condition was studied in the research, and effects such as Cu2+ concentration, concentration of compensation potassium ions, water stirring speed, temperature and hydraulic retention time (HRT) on the removal efficiency of Cu2+ were also investigated. The results showed that when the initial concentration of bivalent ion Cu2+ was 0.0787mmol/L （5mg/L）, under the experimental conditions of the water temperature at 25 °C , the HRT was 6h, the hydraulic mixing speed was 600±25rpm, and the concentration of the compensation ion K+ was 10 times as that of Cu2+, and the removal efficiency of Cu2+ could be achieved 85%. In addition, using the same equipments, when the inlet concentration of Cu2+ increased to 0.787mmol/L (50mg/L), the removal efficiency would be decreased to 76%; while the ratio of concentration of compensation potassium ions to that of inlet Cu2+ is larger than 20, the removal efficiency would not change significantly as the ratio continued increasing; the removal efficiency would be decreased to 60% when lowering the stirring speed to 300±25rpm; the removal efficiency would be decreased to 68% when lowering the temperature to 15+1 °C; the removal rate was no significant change when the hydraulic retention time (HRT) from 6h to 12h.

Abstract: The simultaneous removal of SO2 and NO was investigated with the activated carbon from sewage sludge (referred as ACS) modified by chitosan (referred as CS).The effects of CS loading and operating conditions on the simultaneous removal of SO2 and NO were analyzed. The results indicate that compared with the ACS, impregnating CS results in significant increase in SO2 or NO removal. Relative humidity enhances SO2 adsorption capacities, but not for NO. The SO2 adsorption capacities of the CS / ACS show no obvious decrease at small amount of NO in the feed. However, higher amounts of NO reduce the SO2 adsorption capacities. The opposite phenomenon appears for NO when a small amount of SO2. So a competitive sorption consists between NO and SO2. Simultaneous adsorptions for NO and SO2 is due to more active sites from CS.

Abstract: In order to evaluate the effects of constructed wetland treating oily wastewater, wastewater treatment was monitored during five months. The results showed that when the influent flux was 1.2m3/d, the mean removal rates of COD, TN, NH4+-N and mineral oil in the horizontal flow constructed wetland were 54.27%, 53.47%,54.84% and 50.19%, respectively. Constructed wetland had better removal efficiency and run stably in the treatment process of oily wastewater.

Abstract: It tends to produce high-turbidity raw water during the initial period of typhoons or storms and affect the operation of the purifying system. In this research, Raw water suspended solids roughly to 5,000-9,000 mg/l, the removal rate can be to about 70%-90 %, and reduced to 800 mg/l or less, 8 ml/s minimum about 100-400 mg/l. Overall, the quality of effluent water with the overflow water height increased removal rate rose gradually reduce the suspended solids concentration, gravity settling and effective appear, especially the section Ⅳ region (40 cm) removal are more than 80 %, flow 100 ml/s to 84 %, compared with I (10 cm) with 100 ml/s for 74 %, with obvious benefits. The overflow height of the flow of 8 ml/s, and suspended solids by the inlet concentration at 7,400 mg/l to 8,700 mg/l, down to the effluent concentrations are below 300 mg/l, which overflow height of 20, 30, and 40 cm can be reduced to below 200 mg/l, showing that gravitational sedimentation can significantly remove the high concentration of suspended solids.