Advanced Materials Research Vols. 610-613

Abstract: This paper describes the application of population balance models to activated sludge flocculation process. It presents the development and selection of appropriate expressions for aggregation and breakage kinetics within the population balance framework to describe the evolution of mean size and steady state distribution of flocs under shear conditions. A size and velocity gradient dependent collision efficiency is introduced into the aggregation expression. In the model, only 2 parameters need to be estimated: collision efficiency coefficient and the breakage frequency coefficient. They are obtained by the “best fit” with the experimental data, and keep unchanged under different shear condition for the same flocs. The modelling results indicate that the population balance models coupled with suitable aggregation and breakage kinetics is appropriate for describing activated sludge flocculation dynamics.

Abstract: The oxidation of methanthiol and thiirane in supercritical water was explored by using a tubular-flow reactor system using oxygen as oxidant. No sulfur containing species existed in the gaseous effluent. Sulfide, sulfite and sulfate were detected as the sulfur containing species in the liquid effluent for supercritical water oxidation (SCWO) of methannthiol, while it was determined as thiosulfate, sulfite and sulfate for SCWO of thiirane. When reaction temperature exceeded 873K, the sulfur contained in the methanthiol or thiirane all transformed into the liquid products. Oxidant stoichiometric ratio had little effect on the conversion rate of sulfur but could promoted sulfite converted into sulfate. Sulfide and thiosulfate were determined as the exclusive sulfur containing product arising directly from methanthiol and thiirane, respectively. The transformation pathways of sulfur contained in the methanthiol and thiirane were proposed as methanthiol-sulfide-sulfite-sulfate and thiirane-thiosulfate-sulfite-sulfate, respectively.

Abstract: The research is to compare the adsorption of humic acid from aqueous solution and organic matters from natural water on several adsorption resins by static and kinetic adsorption test. The results of static adsorption show that adsorption resins 213 and SD500 have better adsorption efficacy for humic acid than D203 and 201. The results of kinetic test show that adsorption and elution effect of organics on the smaller size resins are better than the larger ones during 4 operation cycles, and the adsorptive property of SD500 is more stable than 213. It proves that SD500 with grain size less than 0.88mm can be regenerated easily and the adsorption capacity can be restored well.

Abstract: The CMAQ model (Community Multiscale Air Quality model) was used to stimulate the atmospheric environmental quality of Chengdu urban agglomeration. The result shows that air pollutant concentration in some zones of the urban agglomeration is higher than the allowable limit of the national grade II standard. Fortunately, such zones only cover a small area. Zones where the average daily and annual PM10 concentration is higher than the allowable limit only account for 4% of the total area of Chengdu urban agglomeration. Less than 1% of the total area has the concentration of other pollutants higher than the limit. Zones with pollutant concentration higher than the limit are mainly distributed in Chengdu City, Mianyang City, and Meishan City. Pollutants emitted from the cities of Chengdu urban agglomeration shift on to and interact with each other. Therefore, the air pollutant concentration of one city is partially attributable to pollutants emitted from its own pollution sources and a part of or even most of it results from pollutants from other cities. For example, regarding PM10 in air of Deyang City, only 12% comes from its own pollution sources, and 55% comes from pollution sources of Chengdu, and the rest 29% comes from pollution sources of Mianyang. Regarding Sulfur dioxide in air of Chengdu, 59% comes from local pollution sources of Chengdu and 23% comes from pollution sources of Deyang. Other pollutants are also subject to such a rule. As in the urban agglomeration, there are zones where pollutant concentration is higher than the allowable limit, the existing pollution sources must be further controlled by setting reduction target according to the total capacity. The pollutant emission should be reduced by means of eliminating backward productivity, adjusting structure and layout of industries, and controlling pollution sources in depth to effectively improve the regional environmental air quality. At the same time, as pollutants emitted from the cities interact with each other, the 5 cities must sign a joint prevention and control agreement to collaborate in control of sulfur dioxide, nitrogen oxides, smoke and dust, and organic pollutants.

Abstract: High-salinity mine water has been often treating with electrodialysis, multi-effect. But there are still some problems. So we study high-salinity mine water treatment for 24 days with different plants and salinity. The sample was selected from Zhang Xiao Lou coal in Xuzhou. The resultes show that: Cress is able to adapt the water with high salinity and absorb the contamination. When the dosage of NaCl is 1 g/L and 2 g/L, TDS removal efficiency can reach 69.36% and 56.47%. With the increase of NaCl from 0 to 1 g/L, the treatment capacity of the plant increased gradually, and the treatment capacity would decline if the dosage sustained increase. TDS removal efficiency was best, when the dosage of NaCl is 1 g/L, respectively: 56.47%, 50.21% and 44.00% with different plants, and the plants also has a good effect on the removal of COD and nutrient element when the dosage of NaCl is 1 g/L.

Abstract: The purpose of this Research is to simulate the water quality of varied High-turbidity Raw Water at different depths under the water’s surface. During the experiment, a Barrier Board was used to extend the flowing route and to change the overflow level for carrying out the pre-treatment of High-turbidity Raw Water through the changes of varied flow rates in order to study the changes and the removal rate of the turbidity for the influent and effluent; with the settled bottom mud surveyed, the operating requirements of the Surface Overflow Rate (SOR). The experimental result indicated that the turbidity of High-turbidity Water can be reduced by means of an inertia restrained flow, extending the flowing route and heightening the overflow level. The results indicated that the turbidity of the effluent was mostly between 380-1,000 NTU in presenting an over 50% removal rate and even up to 93%. When the SOR of the Sedimentation Basin is set at 19.l m/d, a 54-86% turbidity removal rate can be achieved; whereas, a 50-72% removal rate can be achieved when set at 38.3 m/ d. It has indicated that a significant effect could be achieved for turbidity treatment by employing the properties of high-turbidity substances and the convenient physical theory of gravity settling. As such, a visible removal effect could be achieved to exhibit the effect of pre-treatment.

Abstract: A surface-flow wetland and a subsurface-flow wetland respectively were constructed at the entrance of Dian Lake in Yunnan Province. Six plants such as Canna indica L., Scirpus tabernaemontanl Gmel., Eichornia crassipes (Mart.) Solms., Oenanthe ja vania (Bl.) DC., Acorus calamus L., Phragmitas communis Trin. were planted in the two constructed wetlands in separated sections on condition that hydraulic loading was 12 cm/d, hydraulic retention time (HRT) was 3 d. The results show that the removal efficiencies of subsurface constructed wetlands on TP and TN with canna indica L. or Scirpus tabernaemontanl Geml. are stable. Removal efficiencies of the former on TN and TP are 70.60% and 88.27%, respectively. Removal efficiencies of the later on TN and TP are 73.33% and 83.87%, respectively. Removal efficiencies of the constructed wetlands with Acorus calamus L. and Phragmitas communis Trin., the removal efficiencies of TN are 71.73% and 74.33%, respectively, and removal efficiencies of TP are unstable. The subsurface wetland of Eichornia ciassipes (Mart.) Solms. and Phragmitas communis Trin. on removal of TP and TN in summer or fall are more efficient. The two types of constructed wetlands have good effect on the removal of COD, which are above 78%, and the effluent concentration of CODcr is less than 57 mg/L .

Abstract: A new over-fire air (OFA) program is proposed for Foster Wheeler (FW) type arch-fired boiler: the OFA nozzles are setting on arches near the furnace center and emitting OFA flow into the furnace at an inclined angle. Cold airflow experiments were conducted to determine the effect of the OFA velocity on the aerodynamic field in a small-scale furnace modeled for a 660-MWe arch-fired boiler. As the OFA velocity increases, the penetration depth of the OFA flow increases and the turning point of the OFA flow moves to the furnace center. At the same time, the vertical velocity of arch-injected airflow reduced faster because of the attracted effect of the OFA flow with higher velocity. When the OFA velocity is 22.39m/s (corresponding to 30m/s in the actual boiler), the OFA flow could penetrate to the furnace center and mix with the upflowing gas completely, while the arch-injected airflow have sufficient travel distance and enough residence time in the lower furnace. Thus, considering the penetration depth of arch-injected flow and the OFA flow, an OFA velocity of 22.39m/s recommended according to the present work.

Abstract: Basic oxygen furnace (BOF) gas dry dedusting technology has technical superiority in high efficiency energy conversion, energy saving and emission control and clean environmental protection fields, and it can decrease water consumption greatly, have high efficiency for steam and gas recovery, and reduce environmental pollution, and it is a key technology for realization of high-efficiency energy conversion in the contemporary steelmaking. As to 300t converter blowing process is studied in comprehensive and systematic way by means of the theoretical research of metallurgical process, analysis of process flow and function and engineering optimization of CFD numerical simulation, as well as precise control technology and safety operation technology on BOF gas dry dedusting process in order to realize goals of stable operation process, high-efficiency energy recovery and obvious reduction of emission. After 3 years’ production and practice, BOF gas dry electrostatic precipitator dedusting system has been proven by its outstanding economic environmental benefits.

Abstract: a submerged membrane bioreactor was used to treat the effluent of a pharmaceutical wastewater treatment system, the treated water is rich in ammonia nitrogen and organic compounds (NH4-N, averaged in 78.1 mg/L; COD, averaged in 189.5 mg/L), the final effluent of membrane bioreactor was stably below 50 mg/L COD and 40 mg/L NH4-N respectively, the activity of nitrifying bacteria was inhibited by high concentrations of organic compounds and ammonia nitrogen, a rapid declination of filtration was probably resulted form high concentrations of organic compounds and biomass.