Advanced Materials Research Vols. 233-235

Abstract: Large quantities of ammonia-nitrogen (-N) in wastewater is one of the main causes of eutrophication that endanger both natural water bodies and fresh water seriously. Thus, it is necessary to find an economic and feasible method to remove the ammonium-nitrogen in wastewater before they are returned to the environment. Magnesium ammonium phosphate precipitation method is one of the effective technology of wastewater treatment. In this paper, the influence of initial ammonia-nitrogen concentration, pH, temperature and mole ratio of :NH⁺₄ :Mg²⁺ were studied, What is more, the optimum condition of this process was determined. The results indicated that ammonia-nitrogen concentration is decreased from 1434 mg/L to 95.65 mg/L, and the removal rate reached 93.33% at the optimum conditions, which laying a foundation for the following biochemical treatment.

Abstract: The paper describes the kinetics of MnO₂ from electrolytic manganese (EM) anode slimesleached by SO₂.The effects of stirring speed,SO₂ concentration,temperature, and partical size on the leaching rate of manganese are discussed. Experimental results indicated that the leaching of MnO₂ by SO₂ is 0.86 order with respect to SO₂ concentration. The apparent activation energy values for re-action is 25.7KJ/mol,which is consist with the values of activation energy for diffusion control. The kinetic equation can be expressed as: 1-(2/3)x-(1-x)^2/3=(k₁/ρr){[SO₂]^0.86exp(-25700/RT)}t. Meanw-hile, comparative experiments were operated, using analytical class MnO₂ and pyrolusite, the differ-ence among the three MnO₂ simples reaction with SO₂ was identified.

Abstract: A new coagulant polysilicate iron and zinc (PSFZn) was prepared by using sodium silicate, inorganic acid, ferric chloride, zinc chloride as raw materials, the factors of (Fe+Zn):Si molar ratio, Fe:Si molar ratio, reaction temperature, reaction time and the dosage on coagulation performance were tested. The results showed that the best preparation condition of PSFZn were 60min of reaction time preparation, 30°C of temperature and 4:2:3 of n(Fe):n(Zn):n(SiO₂). When the dosage was 0.4mL·L^-1, the removal efficiency of turbidity was the best which could reach 98.07%. At the same time, it could be concluded that the coagulation mechanism of PSFZn was the combined action of the electric neutralization, the adsorption bridging and sticks the attachment to sweep, which was also the action of the silicic acid, the metal ions and the ions hydrolysate to the muddy colloid pellet in the simulated water sample.

Abstract: This research studied the nitrogen and phosphorus removal from eutrophied lake type water by electro-flotation technique. The effects of operational parameters such as plate spacing, current intensity, electrolysis time on nitrogen and phosphorus removal were investigated in detail. The results showed that current intensity and plate spacing had influence on removal of TN and TP. Under the conditions of plate current of 0.6 cm, current intensity of 1.2 A, electrolysis time of 30 min, the removal of TN and TP was up to 34.30%, and 31.53%, separately.

Abstract: Bacillus cereus was embedded in powdered activated carbon to prepare immobilized granule. Then, the granules was used to treat the Cr(VI) in tannery wastewater. The results showed the removal effect of Cr(VI) removed by the immobilized Bacillus cereus was better than either the single powdered activated carbon or the single Bacillus cereus. SEM photograph showed that the Bacillus cereus in the granules grew well. After the total chromium and the Cr(VI) in the solution and the granules were detected before and after treatment, it was found that the Cr(VI) in the solution and the granules was decreased, but the total chromium was changeless, which indicated that the removal of Cr(VI) with the granules was mainly as the results of both the chromate reductase produced by Bacillus cereus and the adsorption of activated carbon. The kinetics data of Cr(VI) removed by immobilized Bacillus cereus could be well-described by pseudo-second-order rate model. The experiments demonstrated that the immobilized Bacillus cereus could be selected as a new biomaterial to remove Cr(VI) in tannery wastewater.

Abstract: Biodegradation of 2, 2-bis (p-chlorophenyl) -1, 1, 1-trichloroethane (DDT) in soil by white rot fungi and laccase under different experimental conditions was investigated. DDTs stands for the sum of p, p′-DDE, o, p′-DDT, p, p′-DDD and p, p′-DDT in soil. The results shown that the residues of DDTs in soils with different pH levels decreased by 79%, 76%, 73%, 70% and 67% after 28 days of incubation with white rot fungi and laccase, respectively. The residues of DDTs in different pH soils decreasing order was: pH4.5>pH3.5>pH5.5>pH2.5>pH6.5. The residues of DDTs in soils incubated with white rot fungi and laccase decreased with the increase of pollution levels of DDT, the residues of DDTs decrease by 47%, 56% and 70% after 28 days of incubation with white rot fungi and laccase, respectively. The white rot fungi and the laccase extract from white rot fungi can rapidly and efficiently degrade DDT in soil.

Abstract: Because the manganese removal ability of TGV manganese sand filter decreases a lot in A water plant, in this study full-scale experiment and electron microscopy analysis were conducted to evaluate the actual manganese removal ability and explore a method for regeneration in production. The results showed that the manganese sand had lost the manganese removal ability, and the principle of manganese removal was physical adsorption. The maximum adsorptive capacity was measured to be 7.2 (mg manganese ions)/ (g manganese sand) through bench scale experiments, that meant the sand filter could work effectively for 7-8 months, and then the manganese sand would become invalidate. It was recommended to dip 1 litre manganese sand in 500 ml sodium hypochlorite with 0.35% effective chlorine to achieve regeneration, and the cost was acceptable.

Abstract: The adsorption and desorption of tetracycline were investigated by static experiments, and two kinds of activated carbons were employed as adsorbents. And related properties of the adsorbate and adsorbents were studied to support the adsorption mechanism exploration. The results suggested that fairly strong H-bonding exists between the functional groups of activated carbons and tetracycline.

Abstract: Investigated the sorption kinetics of methylene blue on spherical chitosan resin. Studied the influences of ionic strength, pH， initial concentration on the adsorption process. The adsorption of methylene blue increases with the decreasing ionic strength and the increasing pH and the initial concentration of the system. Furthermore, the adsorption process correspondes with Lagergren pseudo-second kinetic equation and the finess (R²) of the model was above 0.99.

Abstract: The anode of DSA (SnO₂/Sb₂O₃/IrO₂) was prepared with the brush coating thermal decomposition method. The surface crystal particles of the DSA were plump, evenly distributed dense coverage and less cracks. The electro catalytic has been enhanced. Compared with the original titanium board, the useful life of electrode was extended obviously, and removal efficiency of N, N-dimethylformamide (DMF) increased to 85.4%.