Advanced Materials Research Vols. 1010-1012

Abstract: This article saw upstream and downstream enterprises in the same watershed as two overalls.Firstly, created a mathematical programming model of pollution control costs and upstream and downstream enterprises’ emissions reductions.Harnessed the method which solved the feasible solutions of the vector optimization problems meeting Kuhn-Tucker conditions to calculate two companies’ marginal treatment costs and put them as the market price of emission rights trading.Then created two companies’ benefit functions and found their Nash equilibrium outputs and incomes.Next analyzed the impacts of the emission trading price on two companies’ equilibrium and calculated the specific range of price parameter.Finally, gets the conclusion that only a reasonable emission trading price can lead to rational resources allocation.

Abstract: It is important to develop low cost and efficient technique for simultaneous removal of SO₂ and NO_X from flue gas. In this paper, ozone oxidation and alkaline wastewater washing process was employed for flue gas desulfurization and denitrification in a 75t/h coal-fired boiler. In order to optimize the operation parameters for SO₂ and NO_X removal, the influence of several parameters, such as molar ratio of [O₃]/[NO] and flue gas temperature on the oxidation rate of NO, oxidation rate of NO, alkaline water level in aeration tank, alkaline water rate and mole ratio of [NaOH/ (SO₂+NOx)] on the removal efficiency of SO₂ and NO_X have been studied. The experimental results showed that molar ratio of [O₃]/[NO] had limited effect on the oxidation of SO₂, while NO oxidation efficiency improved with the increase of [O₃/NO] molar ratio and it reached to ~ 90% at molar ratio of [O₃]/[NO] = 1.4. Flue gas temperature performed slight influence on the oxidation of NO in the range of 60 to 120 °C, and had adverse impact on the removal of SO₂ and NO_X. NO_X removal rate was enhanced with increasing NO oxidation rate and achieved to a high level at NO oxidization rate of ~50%. Mole ratio of [NaOH/ (SO₂+NOx)] had significant impact on the removal rate of NO_X, while it showed limited effects on that of SO₂. The increase of alkaline aeration water level and alkaline water rate would definitely lead to a higher removal rate for both SO₂ and NO_X. An optimized removal rate of 93.6% for SO₂, 77.6% for NO_X and 99.1% for dust were obtained under the water level of 20cm and volume of 74.5t/h.

Abstract: The removals of PM_2.5 from coal combustion by electrostatic precipitator (ESP) and wet flue gas desulfurization (WFGD) system with adding chemical agglomeration solution were investigated experimentally based on coal-fired thermal system. The experimental results show that the average diameter of particles could grow more than four times with the effect of wetting, liquid bridge force and adsorption bridging, and the PM_2.5 concentration of ESP outlet can decrease 40% under typical flue gas conditions. The removal efficiency of fine PM_2.5 is improved about 30% when adding chemical agglomeration solution before desulfurization tower.

Abstract: Study on the pretreatment of printing and dyeing wastewater with PAC、Fe₂(SO₄)₃ and FeCl₃ was carried out. Effects of the flocculants dosage, pH on the treatment efficiency were studied. The results showed that with PAC, Fe₂(SO₄)₃ and the FeCl₃ dosage rising, the treatment effect first decreased and then increased and when the addition amount was 300 mg.L^-1、300mg.L^-1and 250 mg.L^-1,the COD removal efficiency achieved 69%、78%、74% , respectively. With the rising of pH, the treatment effects of the three types of flocculants increased first and then decreased, the optimum pH of PAC and Fe₂(SO₄)₃ was 7and the best pH of FeCl₃ was 6. At last, the settle ability and the amount of the producing floc were studied, the results showed that the settle ability was the best and the least amount of sludge produced by FeCl₃ flocculation. Keywords: printing and dyeing wastewater, pretreatment, flocculants, screening.

Abstract: The control and regulation of SOx emissions have become a global urgent problem for the environment protection. In the field of ocean and marine engineering, The International Maritime Organization (IMO) has formally passed the amendment of MARPOL 73/78 Annex VI in 2008 that clarified the deadline of requirements on SOx emissions limit. A limitation of 3.5 %mm is strictly requested during 2012 to 2020. Hence the SOx emissions of marine diesel engines faces unprecedented challenges while effective control and regulation systems on the SOx emissions reduction are scarce in the existing ships. To meet the IMO's requirements, this paper has presented a novel seawater exhaust gas cleaning (EGC) system for the SOx emissions reduction of marine diesel engines. The post-combustion desulfurization technology was employed in the EGC system. The carbon ion and hydrogen ion contained in the seawater have been introduced into the EGC system to participant the reaction of desulfurization. The seawater EGC system has already been established in a real ship. Experiments have been carried out with the established seawater EGC system to comparatively analyze SOX emissions characteristics when burning different oil types, including heavy oil and light oil. The experiment results show that the newly established seawater EGC system can achieve satisfactory performance with a desulfurization efficiency of 88%. More important, the standard of the SOX emission limitation set by IMO has been met by using the proposed EGC system.

Abstract: Emission of coal dusts can cause serious air pollution in coal-pile storage yard, which poses a threat to human health. Therefore, the quantitative research on particulate emissions is the premise for dealing with atmospheric pollution. In this paper, a series of experiments are firstly carried out in wind tunnel to study the impact of the wind velocity and water content on coal dusts for the mixing pile. Moreover, particle entrainment is investigated by measuring the velocity required to pick up particles from rest, also known as threshold velocity. Then a number of experimental data are obtained and a fitting formula is derived with the aid of Matlab. Finally, the results are compared with those published previously, and explanations about the differences are given.

Abstract: EM enrichment culture liquid was immobilized on nano-silica carrier consisting of pond sediment, zeolite powder and nano-silica to form microbial nano-silica ball. Influencing factors of initial ammonia nitrogen (NH4+-N), COD, pH and dissolved oxygen (DO) concentrations on wastewater purification by microbial nano-silica ball were studied. The results showed that removal rate of NH4+-N, total nitrogen (TN) and total phosphorus (TP) was the highest with COD concentration of 500mg/L when initial COD was ranged from 250 to 2000mg/L. On the condition of initial NH4+-N concentration ranged from 50 to 500mg/L, removal amount of NH4+-N and TN in wastewater reached the maximum when NH4+-N concentration was 400mg/L. On the condition that pH was ranged from6 to 9, removal effect of pollutants was the best when pH was 8. The results also showed that NH4+-N and TN removal rates in wastewater could be increased by appropriate aeration. But aeration had no effect on TP removal rate in wastewater.

Abstract: Mining process will produce a lot of waste mud, and since these indiscriminate matter will lead to the surrounding environment pollution, and human and animal health problem, safe disposal of waste mud is more and more important today. In this paper some common methods, such as direct emission, inject into safe strata, landfill disposal, seal in the pit, land farming, solid-liquid separation, solidification and microbiological method were mainly described, respectively. And a new method of waste mud treatment“fertilizer additives”is inducted and discussed in this paper also.

Abstract: In order to study the effect of dust removal in the electrostatic precipitator under the influence of change of temperature and air moisture of flue gas, the ultrasonic atomization and electrical heating has been adopted for simulated gas to change its air moisture and temperature. The specific resistance of fly ash of fluidized bed boiler, the V-j characteristics of the precipitator model and the efficiency of dust removal has been tested in gas working conditions. The measured results of dust specific resistance shows that: when the temperature of gas at range of 100°C to 150°C, the specific resistance of dust was lower when the air moisture is at 23.73% than at 5.21%, especially when the gas temperature is below 120°C, the specific resistance of dust reduce more,and it can reach the orders of magnitude at10¹⁰Ω·cm when the moisture of 23.73%; then keep the temperature at 150°C and make the moisture increased, the specific resistance of dust is decreased, however it is still more than 10¹¹Ω·cm when the moisture is increased to 23.73%. The measured results of V-j characteristics of the precipitator model shows that: when the moisture keeps at 23.73% and the temperature is below 120°C, the electric field does not occur the phenomenon of anti-corona. The test result of the efficiency of dust removal indicated that: when we make the moisture increased to 23.73% and the gas temperature below 120°C, the efficiency of dust removal shows a significant increase. The results confirmed that we can improve the purification efficiency of high resistivity dust through flue gas humidification and proper temperature maintain.

Abstract: A photovoltaic cell company located in China used with double pass reverse osmosis method to treat low concentration fluoride wastewater. Product water entered the pure water preparation system to recycle. The design capacity of wastewater was 180m³/h. The project improved the pretreatment methods, the operating conditions and the cleaning methods of membrane, so as to prevent membrane blocked and increase of service life. This project ran stability.The water treatment cost was about 4 yuan/t, lower than the local water price.