The biofiltration of indoor air: implications for air quality

An alternative method of maintaining indoor air quality may be through the biofiltration of air recirculating within the structure rather than the traditional approach of ventilation. This approach is currently being investigated. Prior to its acceptance for dealing with volatile organic compounds (VOCs) and CO2, efforts were made to determine whether the incorporation of this amount of biomass into the indoor space can have an (negative) impact on indoor air quality. A relatively large ecologically complex biofilter composed of a ca. 10 m2 bioscrubber, 30 m2 of plantings and a 3,500 litre aquarium were established in a 160 m2 'airtight' room in a recently constructed office building in downtown Toronto. This space maintained ca. 0.2 air changes per hour (ACH) compared to the 15 to 20 ACH (with a 30% refresh rate) of other spaces in the same building. Air quality parameters of concern were total VOCs (TVOCs), formaldehyde and aerial spore counts. TVOC and formaldehyde levels in the biofilter room were the same or significantly less than other spaces in the building despite a much slower refresh rate. Aerial spore levels were slightly higher than other indoor spaces but were well within reported values for 'healthy' indoor spaces. Levels appeared to be dependent on horticultural management practices within the space. Most genera of fungal spores present were common indoors and the other genera were associated with living or dead plant material or soil. From these results, the incorporation of a large amount of biomass associated with indoor biofilters does not in itself lower indoor air quality.     

Effect of surface laminate type on the emission of volatile organic compounds from wood-based composite panels

As a part of understanding the influence of wood-based panels on indoor air quality of a building, this study examined the effects of laminate type on the emission of volatile organic compounds (VOCs) such as formaldehyde, toluene, and total VOCs (TVOCs) from particle board (PB) and medium density fiberboard (MDF) panels, using a 20-L small chamber method. Five different types of surface laminates, including three types of surface overlays such as low pressure laminate (LPL), poly(vinyl chloride) (PVC) film, and urethane coated paper (UCP), as well as two types of surfaces coatings, i.e. direct coating (DC) and ultra-violet coating (UVC) were applied to the veneer bonded to a surface of PB and MDF panels that were of different grades with respect to formaldehyde emission (FE) such as E ₀, E ₁, and E ₂ before surface lamination. As expected, the FE grade strongly affected the FE of panels, regardless of types of panel and laminate. All types of surface laminations dramatically reduced the FE compared to the control. However, the surface laminations by overlay significantly decreased the emission of TVOCs and toluene while both types of surface coatings greatly increased the emission of TVOCs and toluene. In particular, styrene was the main component of TVOCs from the DC sample (about 87%), while toluene was the main species of TVOCs from the UVC sample (about 73%). When two different ways of sample preparation (i.e., single- or all-surface exposure) were compared, the FE of the MDF sample was influenced by the surface exposure type. But TVOCs and toluene emissions were independent of the FE grade and the sample preparation. These results suggest that a proper selection of the surface laminate for wood panels has a significant impact on indoor air quality of a building.     

生物膜法在香料厂有机废气治理的应用

生物除臭,即生物膜法除臭,就是将微生物固定附着在多孔性介质填料表面,利用微生物的新陈代谢生命活动将废气中的有害物质转变为简单的无机物及细胞质并降解成CO2、H2O和中性盐的处理技术。文章分析生物膜法除臭技术在某香料厂有机废气治理的应用实例,实践证明生物膜法除臭对香料厂恶臭处理效果明显,对TVOCs去除率可以达到90%左右。     

The effect of the wind speed velocity on the stack pressure in medium-rise buildings in cold region of China

This paper presents the numerical simulation results of the stack effect in medium-rise buildings in Harbin, a typical city in the severe cold region of China. The simulation was carried out using the multizone ventilation model COMIS. The effect of the wind speed velocity and the temperature of the stairwell on the pressure difference curves shape have been investigated. The pressure difference between the stairwell and the outside shows a linear variation with the height. However, the wind speed velocity may have a strong effect on the pressure difference. The results of the simulation show that at high wind speed velocity the curve of the pressure difference is not linear in shape. It has been also shown that the air total change cannot be provided by only infiltration due to leakage particularly for such air-tight residential building in windy cold climate. Therefore, mechanical ventilation is required to compensate for the lack of it. A quantitative evaluation of IAQ based on the total volatile organic compounds (TVOCs) concentration has been done. The effect of the wind speed velocity and the temperature of the stairwell on the VOTCs concentration at each floor have been also presented.     

人体移动对建材VOCs散发影响的研究

装饰性建材、通风系统、以及人体行为方式影响着人体污染物的吸入剂量。本文以侧送风系统为例,模拟了某工人在安装木地板过程中,来自地板与通风系统的污染物的吸入剂量。基于模拟结果,分析了人体移动对室内环境参数、通风效率、贡献率的(CRP)等指标的影响,其结果对于安装人员的工作环境的改善具有一定意义。