[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.
为揭示化感物质抑制藻类的机理,研究了芦苇化感物质2-甲基乙酰乙酸乙酯(eathyl-2-methyl acetoacetate,EMA)对蛋白核小球藻、铜绿微囊藻和普通小球藻细胞膜磷脂脂肪酸种类、含量以及藻细胞亚显微结构的影响,采用Bligh and dye法提取藻类细胞膜磷脂脂肪酸,GC-MS测定脂肪酸种类和含量,透射电镜法观测细胞亚显微结构.结果表明,EMA使蛋白核小球藻细胞膜不饱和脂肪酸亚麻酸、亚油酸含量都增加了14%,而饱和脂肪酸肉豆蔻酸、棕榈酸含量则下降了12%和11%.加入EMA后,铜绿微囊藻细胞膜中不饱和脂肪酸C18∶1和C18∶2含量分别增加了12%和10%,饱和脂肪酸C18∶0和C16∶0含量则下降.EMA对普通小球藻细胞膜磷脂脂肪酸含量没有显著影响.EMA使蛋白核小球藻和铜绿微囊藻细胞壁脱落,细胞膜破裂,细胞内含物渗出,细胞内片层结构解体,细胞核和线粒体结构损坏.EMA对普通小球藻细胞亚显微结构没有显著破坏.
[Objective] This study aimed to investigate the characteristics of phosphorus adsorption on boiler slag and optimize the adsorption process. [Method] Boiler slag was used as an adsorbent in the single-grade adsorption process to dispose the rural domestic sewage. During the course, phosphorus adsorption kinetics and thermodynamics, adsorption operating curve and the minimum boiler slag dosage were analyzed and calculated. [Result] Langmuir adsorption isotherm could be applied to describe the absorption of phosphorus with boiler slag, and the absorption kinetics was confirmed with the pseudo second-order equation. The maximum absorption quantity and the initial absorption rate increased with the rise of temperature, reaching up to 0.159 1 mg/g and 0.169 8 mg/(g·min) respectively at 40 ℃. Thermodynamic variables ΔG0<0 and ΔH0>0 indicated that the entire process was a spontaneous endothermic reaction, and high temperature would facilitate the reaction of absorption. In the single grade adsorption, the minimum adsorbent dosage decreased as the temperature rose; at 40 ℃ the optimum mass ratio of boiler slag to wastewater was 3.31 kg/m3. [Conclusion] The adsorption process with boiler slag as adsorbent is an economical and effective approach for treating rural domestic sewage.
