Air Pollution

[BOOK: “”The Big Smoke” by Peter Brimblecombe ]

(I have a small confession to make. This particular book, I chose it primarily because it just drew my attention. But I also thought it would be a nice introduction to the topic of air pollution. It’s about the condition of the coal burning London of the past.)

“London had gained its reputation as a foggy city from the German travellers of the late seventeenth century, and at first the visitors were disappointed when a fog restricted their view of the capital, but by the nineteenth century many were even more disappointed if they were not confronted by ‘London’s Particular’.”

“Gloom covered the city in the winter months. Even the meteorologists were willing to enter the word ‘gloom’ in their diaries with increasing frequency during the course of the nineteenth century. The psychological and meteorological gloom were no doubt interconnected as there are endless descriptions of the dismal conditions that prevailed in the early part of the London winter.”

“There was increased mortality from disease during times of fog.”

” E. F. Benson’s Description:

A sudden draught apparently had swept across the sky, and where before the thick black curtain had been opaquely stretched, there came sudden rents and illuminations. Swirls of orange-coloured vapour were momentarily mixed with the black, as if the celestial artist was trying the effects of some mixing of colours on his sky palate, and through these gigantic rents there suddenly appeared, like the spars of wrecked vessels, the chimneys of the houses opposite. Then the rents would be patched up again, and the dark chocolate-coloured pall swallowed up the momentary glimpse. But the commotion among the battling vapours grew ever more intense: blackness returned to one quarter, but in another all shades from deepest orange to the pale gray of dawn succeeded one another.”

[BOOK: “”Air Pollution” by Virginia Brodine ]

Hazard: High Air Pollution Potential (HAPP)

[p.70] “While the effect of human activities on the global scale is a controversial question, there is general agreement that these activities are now having an effect on the climate of cities. The thermal pollution of the atmosphere appears small when averaged for the whole globe or for the continents. In the areas where it is already concentrated, it looks much larger and the point when its effects could become severe seems much closer. In some places, man’s activities already rival the sun in producing heat near the surface. In the summer, the amount of heat produced by combustion alone in Manhattan is one-sixth that of the solar energy reaching the ground and in winter it is two and a half times the solar energy at the surface.

..Higher temperatures in cities are the result of surface changes and gaseous and particulate pollution, as well as combustion.

..Thermal radiation emitted at the surface is re-radiated downward by the pollution layer, warming the air over the city. Unlike the self-correcting effect of natural thermal distribution, this warming of the air has a elf-perpetuating tendency – it increases the stability of the atmosphere and thereby decreases the dispersion of pollutants. However, the warming effect of the pollution layer is partially offset by its cooling effect in reflecting and scattering the incoming solar radiation.”

FALLOUT

[p.84] Vegetation acts as a sink for some of the gaseous pollutants. Plants remove hydrogen fluoride, sulfur dioxide, and some components of photochemical smog from the air… However, these other gases are not part of the plant’s natural chemistry and can damage or even kill it.
Chemical fallout: Sulfur /Nitrogen /Lead / Cadmium / Poisons

Radioactive fallout.

MEASURES

Legislation and advanced techniques regarding waste, fossil-fuel burning and pollution from the automobile.

[BOOK: “Biofiltration for air pollution control” by Joseph S. Devinny, Marc A. Deschusses and Todd S. Webster ]

[p.3]

“TYPES OF WASTE GAS TREATMENT

There are two forms of applicable air emissions control. Source control involves the reduction of emissions through raw product substitution, reduction or recycling. However, these reduction mechanisms may reduce the quality of the product or may increase costs. Secondary control involves treatment of the waste gas after it has been produced.

Condensation 

Waste gas contaminants that are concentrated and have a high boiling point may be partially recovered by simultaneous cooling and compressing of the gaseous vapours.  If the waste gas is a mixed pollutant system, recycling will be virtually impossible, and incineration of the condensed liquid may be required.

Incineration

Thermal and catalytic incineration are widely used and effective treatment processes for waste gases. Thermal incineration involves the combustion of pollutants at temperatures of 700 to 1400 C. Catalytic incineration allows process temperatures between 300 and 700 C with catalysts such as platinum, palladium and rubidium. Incineration is the most widely used secondary technique, but costs are high for low-concentration pollutant vapours because of the need for large amounts of fuel. In general, the technology is more suitable for concentrated streams with moderate flow rates.

Adsorption

Adsorption generally occurs on a fixed of fluidized bed of material such as activated carbon or zeolite and is most efficient for treatment of low concentration vapours.

Absorption

Absorption removes the waste gas contaminant with a scrubbing solution. The gas enters a large contactor where the gaseous pollutants are transferred to a liquid phase. Water is the most frequently used scrubbing solution.

Membrane systems

Membrane systems can be used to transfer VOCs from an air stream to a water phase. In a membrane separation system, compression and condensation of the emission stream is followed by membrane separation.

Biological treatment

Gas-phase biological reactors utilize microbial metabolic reactions to treat contaminated air. Biological treatment is effective and economical for low concentrations of contaminant in large quantities of air.

Though a number of different configurations exist, the major air-phase biological reactors are biofilters, biotrickling filters and bioscrubbers.

[BOOK: “”Air Pollution- An introduction” by Jeremy Colls ]

Despite the book claiming that it is an introduction to air pollution, it proved to be very technical and did not offer me with things that could be of use in an app like the ones I have in mind. I did however find something that I thought was interesting visually:

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