Advanced Materials Research Vols. 726-731

Abstract: The optimum preparation conditions of the macromolecule flocculant-mercapto-acetyl chitosan (MAC) using orthogonal experiment were investigated, and its performances were tested by using the wastewater containing turbidity and/or heavy mental ions such as copper, cadmium, mercury, nickel ions as the target in different pH value in detail. The experimental results show that: (1)The optimal preparation conditions of MAC are as follows:the mass ratio of m (chitosan):m (mercaptoacetic acid) is 1:1, pH value is 5.0, and the reaction time is 3.5 h. (2)The selectivity order of different heavy metal ions by MAC is Cd2+>Cu2+>Ni2+ for the same experimental conditions. (3)With the increasing in pH value the removal efficiency of Cu2+ by MAC was enhanced. (4) The removal efficiencies of heavy mental ions were greatly promoted by the cooperation effects for the water sample containing turbidity causing substances.

Abstract: Many studies have demonstrated an association between exposure to ambient Polycyclic Aromatic Hydrocarbons (PAHs) and some serious diseases, such as cancer, malformation and mutation. PAHs is thought as a carcinogenic and mutagenic compound to human health. Coal-fired power plant industry plays an important role in the observed PAHs emission process. However, the PAHs emission characteristic and environment impact in coal-fired power plant is still not fully clarified. In this study, the PAHs distribution characteristic of the flue gas and fly ash emitted from electrostatic precipitator in two coal-fired power plant boilers with the steam capacity 1000t/h and 2000t/h have been studied in China based on USEPA method 0023(sampling part). PAHs concentrations and PAHs emission factors were determined. And the correlation between PAHs emission and the steam capacity of the power plant boiler was discussed. In addition, the PAHs removal effects of air pollution control devices were also included. According to the measured PAHs emission data and the report of China statistical year book, the PAHs emission assessment from the coal combustion process in the large capacity co-fired power plant boilers have been done. Though the PAHs emission value in the large capacity power plant were present within recommended emission limits of energy production, the problem of PAHs emission in large capacity coal-fired power plant shouldnt be ignored due to the huge amounts and long-range transport in soil, water and ambient air.

Abstract: The chemical oxygen demand was over standard seriously due to residual organic additives in sulfonated drilling wastewater, especially sulfonated phenolic resin with hardly degradable chemical structure. The novel solar-assisted catalytic oxidation process was developed to remove the organic pollutants in sulfonated drilling wastewater. The factors including irradiation light source, oxidant, Fe²⁺, were investigated. The results showed that, solar has more catalytic effects than UV on H₂O₂-K₂S₂O₈/Fe²⁺ system, H₂O₂- K₂S₂O₈/Fe²⁺ system was more effective in degrading organic pollutants than H₂O₂/Fe²⁺ and K₂S₂O₈/Fe²⁺, in which the synergies occurred between H₂O₂ and K₂S₂O₈ in the solar-assisted catalytic oxidation process. The removal amount of organic pollutants was increased with the dosage of Fe²⁺ additon. With the catalytic oxidation process developed, the COD was reduced to 114.4 mg·L^-1. Meanwhile, the sulfonated phenolic resin was completely destroyed, and heavy metal was decreased significantly.

Abstract: The sorptive potential of sunflower straw (≤125 μm) for Sr²⁺ from aqueous solution was evaluated. Batch adsorption experiments were carried out as a function of solution pH, adsorbent dosage, Sr²⁺ concentration and contact time. FT-IR spectra and SEM of sunflower straw were employed to explore the functional groups available for the binding of Sr²⁺ and morphology of the adsorbent. Maximum uptake capacity of sunflower straw was 17.48 mg/g occurred at around pH 3-7. The adsorption equilibrium can be achieved within 5 min and kinetic data were fitted well to pseudo-second-order model. The Langmuir and Freundlich models were applied to describe isotherm sorption data. The Langmuir model gave an acceptable fit than Freundlich model.

Abstract: Airlift inner circulation reactor (AICR) consisting of beaker and built-in aeration tank was introduced in this paper. The Dissolved oxygen recovery (R_DO) was highly influenced by the ratios of the height of built-in aeration tank to the height of liquid level in reactor (R_h/H), the diameter of built-in aeration tank to the diameter of the reactor (R_d/D) and aeration rate (Q_N). Average R_DO of 24.25 m.gm^-3.s^-s and DO concentration of 8.97mg.l^-1 were obtained at R_d/D=0.47, R_h/H=0.68 and Q_N =1.0m³.m^-3.min^-1 for aerating 370s at 17°C. The total transferred oxygen in 4L deoxidized water reached 35.89mg, which had an increase by 11.15% than that of the traditional airlift reactor (AR). The DO concentration was 88.33-9.34mg.l^-1 for AICR, but it’s only 7.71-8.58mg.l^-1 for AR.

Abstract: In order to develop a new high-efficient but low-cost sewage treatment technology, sewage treatment experiments have been accomplished in a new type sequencing batch reactor with concrete bio-films. During experiments, simulation sewage was taken as raw water, and the operation sequence of the reactor was taken as 1.25h for water input and hypoxia, 1.25h for aeration, 0.5h for precipitation and 0.5h for water discharge successively. It has been shown by the experimental results that the reactor has optimal sewage purification effects, such as its average pollutant removal rate can arrive at about 95% for COD and BOD₅, near 70% for ammonia hydrogen and about 40% for total phosphorus under the experimental condition. Main factors influencing the reactor purification effect have been discovered as pollutant volume load, ratio C/N, water temperature and amount of bio-films installed in the reactor. The mechanism of their influences has been also discussed in this paper.

Abstract: This paper elaborates the formation, distribution, migration and transformation of mercury and particulate matter, also some of the existing removal process methods. Using the mass balance method calculates the mercury content of coal-fired product. According to the result, we can targeted design a strong practicality, feasibility joint removal process to fine particulate matter and mercury of the thermal power plant.

Abstract: Using coagulation and sedimentation process in the advanced treatment of urban secondary effluent which can be recycled to circulating cooling water system in power plant is only perform well on COD_Cr and turbidity removal. But the concentrations of organic matter and NH₃ in effluent can not meet the requirements of circulating cooling water. Therefore, in this study, the feasibility of biological aerated filter (BAF) as a pretreatment enhancing coagulation and sedimentation process was discussed. Achieved by controlling the two operating modes: (1) secondary effluentcoagulation and sedimentationeffluent; (2) secondary effluent BAFcoagulation and sedimentation effluent.The results show that the BAF pretreatment removes ammonia nitrogen effectively, and the turbidity and COD_Cr of effluent of BAF-coagulation sedimentation process is much lower than individual coagulation and sedimentation process. The final effluent qualities meet the requirements of circulating cooling water system in power plant.

Abstract: The nitrogen oxides emission concentration of a coal-fired units exceeded national standards. This paper analyzed the problem of the denitrification equipment, the denitrification process was transformed with low NO_X combustion and hybrid SNCR&SCR denitrification technique, according to the existing denitrification technology. The nitrogen emission concentration of the coal-fired units reach the current national emission standards after transformation.

Abstract: The microstructures of particulates fueled with ethanol/diesel, DMC/diesel, and biodiesel/diesel blends were studied using the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of oxygenated fuels on the microstructures of particulates were studied. The results showed that the particulates presented with chain and group like structures. The particulate size was approximately following the normal distribution. With the increase of oxygenated fuels blends ratios, the extent of agglomeration increased and the structure arrangement became closer.