3. Air quality (2 points) What is the air quality index (AQI)? a. b. (3 points)

Question

3. Air quality (2 points) What is the air quality index (AQI)? a. b. (3 points) Two researchers at Stanford made a discovery in 1974 that ultimately lead to an amendment of the Clean Air Act in 1977. What did they discover? c. 6 points) In class we talked about several different air treatment technologies. Describe briefly how two of these technologies work. d. (6 points) Calculate the number of plates required to remove a 5.0-um diameter particle with a drift velocity of 0.15 m/sec for an electrostatic precipitator with plates that are 0.75 m x 0.75 m in area. Efficiency = 80%. The gas flow rate is 4.0 m/sec. e. (3 points) What area of bag is required to remove lead oxide in an air/woven baghouse? Gas flow = 5 m/sec

Explanation / Answer

(a) The current air which is present in the atmosphere is safe or polluted these forecast is given by government agencies for the awareness of the public and also it is a number.

(b) This act is mainly taken for the prevention of significant deterioration (PSD) of air quality in areas attaining the National Ambient Air Quality Standards (NAAQS). The 1977 clean air act contains requirements pertaining to sources of geographic areas which does not meet one or more federal air quality standards. finally, these act is for permit review requirements and maintenance of NAAQS.

(c) Mechanical filtration: mechanical filtration is simple and extensively used air pollutant technique for removing suspended particles from indoor air. filters play role in air conditioning systems and to capture particles by interception, impact or diffusion. these technique does not retain gas particles and is fully saturated by particles so, the pressure loss occurs and particle removal efficiency progressively decreases. this problem can overcome by replacing new filters. these spent filters are new sources for contaminating due to the accumulation of material which is cause for the growth of the harmful microorganisms.

Electronic filtration: There are two types of electronic filters that involve particle removal. Electrostatic precipitators and ion generators. Electrostatic precipitators are medium cost devices in which particles are ionized and then deflected by an electric field to be trapped on opposite polarity plates.their maintain includes the regular removal and cleaning of plates. Ion generators are high-cost devices without replacement in which charged ions are dispersed into the air and attached to the particles that become chemically charged and trapped in the filters.   

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