Optimization of a wet scrubber with electrolyzed water spray—Part II: Airborne culturable bacteria removal

Airborne microorganisms, especially the pathogenic microorganisms, emitted from animal feeding operations (AFOs) may harm the environment and public health and threaten the biosecurity of the farm and surrounding environment. Electrolyzed water (EW), which was considered to be an environmentally friendly disinfectant, may be a potential spraying medium of wet scrubber for airborne microorganism emission reduction. A laboratory test was conducted to investigate the airborne bacteria (CB) removal efficiency of the wet scrubber by EW spray with different designs and operating parameters. Both the available choline (AC) initial loss rate and AC traveling loss rate of acidic electrolyzed water (AEW; pH = 1.35) were much higher than those of slightly acidic electrolyzed water (SAEW; pH = 5.50). Using one spraying stage with 4 m sec^?1 air speed in the duct, the no detect lines (NDLs) of SAEW (pH = 5.50) for airborne Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis removal were all 50 mg L^?1, whereas the NDLs of AEW (pH = 1.35) for airborne E. coli, S. aureus, and S. enteritidis removal increased to 70, 90, and 90 mg L^?1, respectively. The NDLs of SAEW (pH = 5.50) for airborne E. coli, S. aureus, and S. enteritidis were lower than those of AEW (pH = 1.35) at single spraying stage. Increase in the number of stages lowered the NDLs of both SAEW (pH = 5.50) and AEW (pH = 1.35) for airborne E. coli, S. aureus, and S. enteritidis. EW with a higher available chlorine concentration (ACC) was needed at air speed of 6 m sec^?1 to reach the same airborne CB removal efficiency as that at air speed of 4 m sec^?1. The results of this study demonstrated that EW spray wet scrubbers could be a very effective and feasible airborne CB mitigation technology for AFOs.

Implications: It is difficult to effectively reduce airborne bacteria emitted from animal feeding operations (AFOs). Electrolyzed water (EW) with disinfection effect and acidity is a potential absorbent for spray in wet scrubber to remove microorganisms and ammonia. Based on the field test results, a laboratory experiment we conducted this time was to optimize the design and operation parameters to improve the airborne bacteria removal efficiency. A better understanding of the EW application in the wet scrubber can contribute to the mitigation of airborne bacteria from animal houses and improve the atmosphere air quality.     

温室效应,太阳活动,南方涛动对我国气候变化的影响

本文用统计方法对我国近百年来的气象观测资料的分析表明,在温室效应导致全球增暖的背景上,我国将出现同步的增暖趋势,东南沿海降水量增加,而西北地区的干旱则将更趋严重,太阳活动和南方涛动对我国气候变化也有显著影响,它们分别可能是温度的22年准周期振动和降水量的准4年周期振动的原因.     

颗粒层除尘器冷态压力损失的研究

本文采用了工业颗粒层除尘器最常用的石英砂滤料进行了固定床压损冷态实验,实验与理论研究结果表明压损与过滤风速呈线性关系,并且服从达西定律,由实验数据得出石英砂滤料的压损系数ξ=1190,线性相关系数r=0.973.所得出的冷态压损计算公式可用于颗粒层厚度设计,同时也为确定过滤风速和反洗清灰动力提供了依据.     

Effects of selected pesticides on , and on seed germination and Verticillium wilt pathogens of alfalfa

Studies on the effects of 21 fungicides and five pyrethroid insecticides on growth of , emergence and survival of alfalfa seed and the efficacy of the chemicals in control of Verticillium wilt pathogens were conducted.     

H2O2协同TiO2光催化处理模拟苯胺废水

采用TiO2光催化处理模拟苯胺废水.实验结果表明,最佳反应条件为:初始苯胺质量浓度10 mg/L,纳米TiO2加入量100 mg/L,光催化反应时间60 min,废水pH 7.5.加入20 mg/L的H2O2协同TiO2光催化处理苯胺废水,光催化反应24 min后,苯胺去除率达99％.H2O2协同TiO2光催化降解苯胺过程符合二级动力学方程.     

自愿协议式环境管理模式在荆州纺织印染行业的实践研究

自愿协议作为环境管理的必要补充日益受到重视,本文对荆州纺织印染行业践行自愿协议环境管理进行了总结,提出了自愿协议式环境管理荆州模式的实施框架和具体内容,调查分析了荆州市部分纺织印染企业履行自愿环境管理协议的具体做法和取得的初步效果。实践表明,企业采取自愿环境协议,有利提高生产效率和管理水平,减少能耗和排污量。为鼓励企业采取自愿环境管理,政府要在政策和资金上给企业予以支持,解决企业因超前环境管理行为面临的资金短缺和成本增加问题。     

模拟废水丁二酸的催化湿式氧化处理

对催化湿式氧化专用的TiO₂载体及Ru-TiO₂催化剂的抗压强度、比表面积、孔体积、平均粒径、晶体结构等重要物性参数进行了表征.在间歇式反应釜上研究了Ru-TiO₂催化剂在处理模拟废水丁二酸(7.40g/L,COD=7000mg/L)中的催化活性、影响因素及金属溶出问题.研究表明:在Ru含量相同的情况下,载体的比表面积、孔体积越大,催化活性越高.经过表面处理的载体制备的催化剂活性显著提高(COD去除率增加约10%).反应受温度、pH值等因素的影响:在反应温度270℃,pH=11.00,起始压力2.3MPa,反应压力7.1MPa条件下,经30min反应,COD去除率为67.4%～95.4%.在间歇式反应釜中连续运行12次后,催化活性稳定,Ru流失甚微.在200L/d的小型工业化装置上一个月的运行,保持COD去除率大于99%,NH₃-N去除率约100%.     

Preparation of a titanium dioxide photocatalyst codoped with cerium and iodine and its performance in the degradation of oxalic acid

A novel class of visible light-activated photocatalysts was prepared by codoping TiO(2) with cerium and iodine (Ce-I-TiO(2)). The particles were characterized using the Brunauer-Emmett-Teller method, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Visible light absorption. Particles of Ce-I-TiO(2) had greater photoabsorption in the 400-800 nm wavelength range than iodine-doped TiO(2) (I-TiO(2)). The effects on the photocatalytic degradation of oxalic acid under visible light or UV-Visible light irradiation were investigated. The photocatalytic activity of Ce-I-TiO(2) calcined at 673 K was significantly higher than that of Ce-I-TiO(2) calcined at 773 K and I-TiO(2) calcined at 673 K in aqueous oxalic acid solution under visible light or UV-Visible light irradiation. Under visible light irradiation, oxalic acid was first adsorbed on the surface of the catalysts rather than reacted with free radicals in the bulk solution, and then oxidized by (·)OH(ads) to CO(2), which was verified by studying the effects of nitrogen purging and scavengers, as well as by gas chromatography/mass spectrometry.     

城市污水处理厂恶臭浓度分布规律及其防治措施

城市污水处理厂的主要大气污染物之一为恶臭污染,恶臭问题已经成为环境领域的一个重要研究课题。恶臭污染物的来源主要是初沉池等水流湍动处,其成分主要是含氮化合物、含硫化合物、含氧有机物等。分析了恶臭污染物的来源、成分和浓度分布等,对确定城市污水处理厂的卫生防护距离进行了讨论,并介绍了目前国内外主要恶臭污染防治措施。湿式吸收氧化法和生物过滤法这两种技术是当前发展和应用的方向。     

Enhanced adsorption of arsenate by spinel zinc ferrite nano particles: Effect of zinc content and site occupation

In this work, zinc ferrite spinel with different zinc contents (Zn_xFe_3-xO₄) was synthesized by a hydrothermal method and used for removing As(V) in aqueous solution. X-ray diffraction (XRD) results indicated that in the crystal structure of Zn_xFe_3-xO₄, the zinc atoms tended to occupy the octahedral sites for x?<?0.6 and diffused into the tetrahedral sites gradually with x?>?0.6. The size of Zn_xFe_3-xO₄ crystallites increased with the increasing zinc content. Batch adsorption experiments showed that the adsorption isotherms could be well described by the Langmuir model, while the adsorption kinetics followed the pseudo-second-order kinetic model. Zinc ferrite exhibited the highest adsorption capacity towards As(V) when x?=?0.6. Study of the mechanism indicated that doping with zinc increased the number of surface hydroxyl groups on ferrite spinel, and thus enhanced the adsorption capacity when x?=?0.6. This work revealed the effects of doping site and content of metal atoms on the adsorption ability of ferrite spinel towards As(V).