Advanced Materials Research Vols. 243-249

Abstract: Iron and manganese oxide /activated carbon composite (GACF1M3) was prepared and the experiment conditions including pH ,GACF1M3 dosage and organic effect were evaluated in the H₂O₂ decomposition. The results showed that the decomposition of H₂O₂ increased with time ,GACF1M3 can decompose H₂O₂ about 75% in 120min . The amount of H₂O₂ reflected the maximum usage rate of the GACF1M3 when the dose was 100mg. The highest H₂O₂ decomposition of GACF1M3 was achieved at pH 8.5, the maximum OH· production was pH 5.0.The presence of HA can increase H₂O₂ decomposition while TCP has the opposite effect.

Abstract: This paper considers on-going problems relevant to operation and maintenance in wastewater treatment plants in China. Positive and negative practices in developed countries such as the UK and U.S. have been indicated for the purposes of comparison. This research looks at the aspects of institutional structure, human resource management, public participation, financial resources, and technical management which have been regarded as the key points to analyse for effective wastewater management. Relevant information has been collected and analysed to develop appropriate solutions that would assist decision-makers and operators to solve some of the problems of wastewater management and to operate and maintain wastewater treatment plants in China properly.

Abstract: This unbiodegradable pharmaceutical wastewater is treated by the process of hybrid hydrolysis acidification technique (HHAT) with anaerobic-low DO condition and the hybrid aerobic bio-technology consisted of alternate-flow biological reactor (ABR) and two-way-flow biological aerated filter (TBAF). The largest plant in pharmaceutical wastewater treatment at home was built. The practice shows that the organics can be greatly removed and the effluent can reach the First Grade Discharge Standard which can be reclaimed with advanced treatment. The performance indicates that the treatment is stable.

Abstract: According to the ineffective denitrification and the initial controlling technique flaws for low-carbon source in reversed A²/O process, and full scale experimental studies were conducted to strengthen denitrification at normal and low temperature days in 2008~2010, to ensure the best conditions of biological denitrification and promote the stable and efficient operation of the system. The results showed that in normal temperature seasons of 2008, after shortening the HRT of the primary sedimentation tank to 1/3 of design value, improving the MLSS to 4500mg/L, setting the first section of the aerobic zone as the denitrification transition section and improving the reflux ratio, available carbon source was increased by 15%, the effluent NH₃-N was 2.5mg / L and the removal rate was 90%, the effluent TN was 17 mg/L and the removal rate was increased to 54% and unit power consumption was reduced by 15% to 0.22Kw•h/m³.At low temperature seasons of 2008~2009,by improving the MLSS to 6000mg/L, extending the sludge age to enrich a large number of nitrification and denitrification bacteria, controlling DO at about 1.2mg / L in the aerobic zone and so on, the effluent NH₃-N was 3 mg / L and the removal rate was 88%, the effluent TN was 15.5 mg/L and the removal rate was 62%. In low temperature of 2009 ~2010, besides the same measures as before, adding a blender in the first section of the aerobic zone to provide a better anoxic environment for denitrification and to improve nitrogen removal, the effluent NH₃-N was 3 mg / L and the removal rate was 87%, the effluent TN was 13.5 mg/L and the removal rate was 66%.

Abstract: Sludge age (SRT) is one of the primary influencing factors in the system of short-cut nitrification, in order to select a suitable SRT, in the stable operation of SBR, with the simulated wastewater as treatment object, the response effect and the sludge floc characteristics of short-cut nitrification are investigated by changing the SRT. Experiment has proved that the longer SRT the more complete nitrification. When the SRT for the 10d time, the NO₂^--N accumulation rate was maximum. When the SRT is short, the biological floc phase composed mainly by bacilli, and the surface of the sludge floc is rough and structure is loose. When the SRT is longer, the reactor's biological floc phase mainly composed by the coccus and has got relatively smooth surface with a compact structure. Rod-shaped bacteria are the good characteristics of the phenomenon of the short-cut nitrification.

Abstract: Phosphorus removal by biological aerated filter(BAF) is ineffective, its effluent TP is much more than 0.5mg/L, so chemically enhanced phosphorus removal is neccessary. To solve this problem, domestic wastewater through BAF by adding metal salts in the aerobic tank was studied. The ferric chloride and aluminum chloride were chosen as the metal salts. The results showed that: the removal rate of TP rose with the Me/P (Me=Fe, Al)mass ratio increased, the influence on other performance of BAF by chemically enhanced synchronously was not severe, with TP in the effluent below the standard of 0.5mg/L; to ensure the concentration of effluent TP was less than 0.5mg/L, the optimum mass ratios of dosing were Fe/P=3, Al/P=2.5; proper aeration intensity could maintain the proper micro-flocculation state in BAF, which was helpful to TP removal.

Abstract: The coagulation experiment, with Kaolin as objects, aluminum chloride (PAC) as coagulant and hydrated MnO₂ as coagulant aid, were accomplished under different conditions. In the experiment, the particle size distribution and turbidity in water were detected by on-line detector. The results show that increase PAC dosage, original turbidity, hydrated MnO₂ dosage and coagulation time will make the fractal dimensions of floc growth in micro-coagulation stage increase. The fractal dimensions of floc growth in micro-coagulation stage increasing means more particle size <5µm flocs are removed. Hydrated MnO₂ can strengthen micro-coagulation.

Abstract: The coagulation experiments, with Kaolin as objects, aluminum chloride (PAC) as coagulant, were accomplished under different conditions. In the experiment, the particle size distribution and turbidity in water were detected by on-line detector. Result showed that all floc changed in speed in the first 5 min of the coagulation process and the fractal dimension of floc growth in the first 4 min of coagulation process had best linear relation (R² was biggest and more than 0.92 )with turbidity, total particle number and the number of particle size <5µm of settled water. The fractal dimension had a direct ratio relation with water quality of settled water and could be used as a factor to forecast water quality of settled water.

Abstract: This research focused on the effect of water temperature and pH to coagulation efficiencies in low turbidity water. And the optimum dose of coagulant was determined. Simulated the treatment processing, the organic matters and turbidity removal capacities of polyaluminum chloride (PACl) were measured in parameters of turbidity, COD_Mn and UV₂₅₄ with different experimental conditions. The results indicated that the PACl optimum doses were 28mg/L. By increasing water temperatures in the range of 4°C～18°C, the turbidity removal efficiency was gradually enhanced, while the organic loading removal performed few correlations to temperatures. And the effective pH range was 6.0~9.0, that appeared greater influence on turbidity removal than organic loadings.

Abstract: Many researchers pay their attentions to the biostability of drinking water more and more. Biodegradable dissolved organic carbon can provide a good indicator for biostability of drinking water in distribution-system. The main objective of this study was to research the regulations of concentration changes of biodegradable dissolved organic carbon and the populations of the total bacteria in water distribution-system of a city in china. The field experiments showed that the values of biodegradable dissolved organic carbon decreased along the main pipes in the water distribution-system, and the rate of the decrease was lower in the front part of the two main pipes than in the back part. At the same time, the populations of the total bacteria increased in the front part of the NO.1 main pipe and decreased in the back part. Our research provided the theoretical foundation for limiting the bacteria regrowth and to ensure the biostability of drinking water.