生物脱臭技术初探

通过以Ｈ２Ｓ为代表的恶臭气体和以活性污泥加热干燥产气对象的脱臭实验，对生物法脱臭机理及影响生物脱臭效果的一些因素进行了有益的研究。     

Removal of AOX, total nitrogen and chlorinated lignin from bleached Kraft mill effluents by UV oxidation in the presence of hydrogen peroxide utilizing TiO2 as photocatalyst

Background, aim, and scope  The pulp and paper industry is the sixth largest polluter discharging a variety of gaseous, liquid, and solid wastes into the environment. Effluents from bleached Kraft mill effluents (BKME) are polluting waters to a great extent These effluents cause considerable damage to the receiving waters if discharged untreated since they have high levels of biological oxygen demand (BOD), chemical oxygen demand (COD), chlorinated compounds (measured as AOX), suspended solids (mainly fibers), fatty acids, tannins, resin acids, lignin and its derivatives, sulfur and sulfur compounds, etc. This study aimed to remove adsorbed organic halogen (AOX), total nitrogen, and lignin-degrading products in the wastewater (4,500 m³/h) from the paper mill in the pulp and paper industry, which is discharged to sea from a plant located in western Turkey. Materials and methods  The photocatalytic degradation of AOX, total nitrogen, and chlorinated lignin in BKME have been investigated in different parameters, such as time, H₂O₂ and TiO₂ concentration. In addition, for investigating the effect of chlorine on the removal of lignin, pure lignin solution was prepared in equal amounts to chlorinated lignin degradation products found in BKME. The same experiments were conducted for this solution. Experiments were carried out in photocatalytic reactor made of Pyrex glass. The mercury lamp was used as a radiation source. All irradiation was carried out under constant stirring. The existence of dissolved O₂ is an important factor which increases the photocatalytic degradation. Hence, we used an air pump for the aeration of the wastewater solutions. The temperature of the wastewater was controlled and adjusted to 25°C by thermostat pump in conjunction with a cooler. At the end of all experiments, AOX, total nitrogen and lignin concentrations were analyzed according to standard methods. All experiments were performed in duplicate and average values were used. Results and discussion  When the effect of H₂O₂ and time were investigated, it was observed that the AOX concentration increased from 3.0 to 11.0 mg/L by only UV. However, when H₂O₂ was added, AOX concentration decreased from approximately 3.0 to 0.0 mg/L. The optimal conditions for the removal of AOX appear to be an initial H₂O₂ concentration of 20.0 mL/L and reaction time of 50 min. In addition, at the same experiment conditions, it was seen that the total nitrogen concentration decreased from 23.0 to 15.0 mg/L by only UV and by increasing H₂O₂ concentration, the concentration of 20.0 mL/L H₂O₂ appears to be optimal (9.0 mg/L). The AOX, total nitrogen and lignin degradation products and pure lignin go through a minimum when the concentration of H₂O₂ and TiO₂ increases at constant pH and UV intensity. The kinetics for the degradation of AOX, total nitrogen and lignin degradation products followed a pseudo-first order law with respect to the products, and the degradation rates (min⁻¹) for the UV/TiO₂/H₂O₂ system were higher than that of the corresponding values for the UV/H₂O₂ system. Conclusions  The AOX, total nitrogen and lignin concentration go through a minimum when the concentration of H₂O₂ and TiO₂ increases at constant pH and UV intensity. It was found that the UV/TiO₂/H₂O₂ system has proved capable of the degradation of total nitrogen as well as chlorinated and degraded lignin in BKME. Recommendations and perspectives  The photocatalytic process can be considered a suitable alternative for the remove of some compounds from the BKME. Nevertheless, further studies should be carried out to confirm the practical feasibility of BKME. Another result obtained from the study is that pre-purification carried out with UV/TiO₂/H₂O₂ photocatalytic process may constitute an important step for further purification processes such as adsorption, membrane processes, etc.     

PM(10)-bound polycyclic aromatic hydrocarbons: biological indicators, lung cancer risk of realistic receptors and 'source-exposure-effect relationship' under different source scenarios

Cancer has become a critical health issue in the world heritage city Kandy, Sri Lanka. Polycyclic aromatic hydrocarbons (PAHs), one of persistent organic pollutants, in the atmosphere may be a major etiological factor in lung carcinogenicity. Over the very high concentrations of ambient air PAHs reported in Kandy, this paper is focused on setting priorities to control human exposure to PAHs in prevention of cancer.On re-appraisal of the classical indicator benzo(a)pyrene (B[a]P) for atmospheric PAHs-related carcinogenicity, B[a]P failed to reflect the toxicity completely and may not be the sole indicator for risk assessment studies in complex multi-sourced urban environments. The excess lifetime lung cancer risks of atmospheric PAHs with ‘less than lifetime exposure’ were assessed based on both ‘B[a]P toxic equivalents’ and ‘B[a]P surrogate epidemiological’ approach of risk quantification, over emissions characterized urban, suburban, and rural areas of Kandy. In urban heavy traffic areas, PAH-related additional cancer burden has been 942 million⁻¹ over 30 y of exposure. Over the whole study area, ∑p-PAHs show strong correlation (r = 0.8) to the predicted risk levels. While the urban and suburban predicted cancer risk levels could not show significant correlation to their emission sources indicating the real complexity in mega urban environments, the rural lung cancer risk levels correlated perfectly with the source, firewood combustion.Policy decisions on environment and health could be based on established correlations among ‘emission sources-exposures-health effects’. The priority for “analysis of options and policy formulation to reduce inhalation PAHs exposure of population in Kandy” was considered “moderate to high”.     

不同挂膜方式生物滴滤塔处理含H2S恶臭气体简

采用菌剂挂膜,活性污泥挂膜和自然挂膜3种不同方式形成生物滴滤塔,考察挂膜方式对生物滴滤塔去除H₂S恶臭气体的影响。结果表明,当进气H₂S浓度为5 mg/m³时,菌剂挂膜、活性污泥挂膜、自然挂膜形成的生物滴滤塔出气H₂S浓度分别为15.7~17.4、11.6~14.8和15.0~15.9 μg/m³;塔内压降分别为3~4 mm水柱、6 mm水柱和4~5 mm水柱;喷淋后滤出液中硫酸根的浓度分别为14、22和17 mg/L,硫的转化率分别为45%、60%和50%。当进气H₂S浓度增大至7 mg/m³时,3个塔经过7 d的调整后,均能达到稳定状态,稳定后3个塔中出气H₂S浓度和压降基本没变,喷淋后滤出液中硫酸根浓度依次增大至25、31和30 mg/L左右。采用活性污泥挂膜形成的生物滴滤塔处理H₂S的能力比菌剂挂膜和自然挂膜的高。     

生物反硝化除磷技术及其研究进展

污水生物反硝化除磷技术的研究在国内才刚刚起步，而在国外尤其在欧洲已经是一个新热点。该文在相关文献的基础之上，针对反硝化除磷技术的机理、工艺及其研究进展，作了综述和比较分析，以给相关的研究工作者提供一些有价值的参考和帮助。     

Radiographic,haematological, and biochemical findings in a fetus with Caffey disease

An early case of prenatal Caffey disease is reported. Ultrasound examination performed at 20 weeks showed major angulations of long bones, but both ultrasound scan and X-rays failed to make the differential diagnosis between Caffey disease and lethal osteogenesis imperfecta. A cordocentesis allowed us to find important biological abnormalities. The pregnancy was terminated after the rapid development of hydrops fetalis. The definitive diagnosis of Caffey disease was obtained by special X-ray and pathological study.     

高盐废水处理研究新发展

高盐废水处理比较困难.传统的物化、生化法处理高盐废水可以达到一定的效果,但都存在着不可避免的弊端。因此,笔者在过去几年国内外高盐废水处理研究的基础上,介绍近阶段高盐废水处理的新方法,总结经验。     

恶臭气体的生物处理技术

叙述了各种生物脱臭的处理方法及其优、缺点以及提高生物脱臭效率的途径，同时还介绍了一些生物脱臭法的最新研究成果和发展方向。     

Effects of benthic hydraulics on sediment oxygen demand in a canyon-shaped deep drinking water reservoir: Experimental and modeling study

Sediment oxygen demand (SOD) is a major contributor to hypolimnetic oxygen depletion and the release of internal nutrient loading. By measuring the SOD in experimental chambers using in both dissolved oxygen (DO) depletion and diffusional oxygen transfer methods, a model of SOD for a sediment bed with water current-induced turbulence was presented. An experimental study was also performed using near-sediment vertical DO profiles and correlated hydraulic parameters stimulated using a computational fluid dynamics model to determine how turbulences and DO concentrations in the overlying water affects SOD and diffusive boundary layer thickness. The dependence of the oxygen transfer coefficient and diffusive boundary layer on hydraulic parameters was quantified, and the SOD was expressed as a function of the shear velocity and the bulk DO concentrations. Theoretical predictions were validated using microelectrode measurements in a series of laboratory experiments. This study found that flow over the sediment surface caused an increase in SOD, attributed to enhanced sediment oxygen uptake and reduced substances fluxes, i.e., for a constant maximum biological oxygen consumption rate, an increased current over the sediment could increase the SOD by 4.5 times compared to stagnant water. These results highlight the importance of considering current-induced SOD increases when designing and implementing aeration/artificial mixing strategies.     

污水中染料的生物毒性及其去除方法的研究

本文介绍了在实验室模拟条件下,利用蚕豆根尖的微核效应,分析了3种染料溶液及实际污水的生物毒性和它的去除方法。实验表明,这3种染料和实际污水都存在着生物毒性。在溶液 pH,温度,臭氧发生量一定条件下,3种染料溶液经臭氧氧化后,生物毒性去除率达56%以上,实际污水经臭氧处理后,生物毒性去除达31.09%。