environmental science

 

HELWAN UNIVERSITY FACULTY OF ENGINEERING MATARIA

 

ENERGY ENGINEERING PROGRAM

BY: ABD BY: ABD EL-RAHMAN AMIN AHMED Supervised By: DR/ Mustafa Ismail

 

  Table of Contents

Measurement of air pollution ............................................. 3-5 oductii on .............. ........................... .......................... .......................... ........................... .................. .... 3   I n tr oduct asur ur eme men n t of of Par ti cul ate M atte atterr   M eas

......... .... ......... ......... ......... ........ ......... ....... .. 4

  M eas asu u r ement ments s of gas gase es .................... ......... ...................... ...................... ...................... ............. 5

Measurement of water pollution ...................................... 6-10   I n tr oduct oductii on .............................. ........................................... ........................... ........................... ............... .. 6

olve ved d Ox Oxyge ygen n ............. .......................... ........................... ........................... ........................ ...........6   D i ssol ochemical cal oxyge oxygen n D eman mand d ............ ......................... ........................... .................... ...... 6   B i ochemi   Ch Che emi cal Ox Oxyge ygen n D eman mand d .............. ........................... .......................... ...................... .........7   Wat Wate er T emper mperatu aturr e ............ .......................... ........................... .......................... ...................... .........7   PH V al alu u e............ .......................... ........................... ........................... ............................ .................... ...... 7-8 7- 8

bidi dity ty .................... .................................. ........................... .......................... ........................... .................. .... 8   T u r bi   Su spe pen n de ded d el ement .......... ..................... ...................... ...................... ...................... ................... ........ 9

References ............................................................................ 12

 

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  M eas asur ur eme ment nt of air po poll ll uti on:



  Air

quality measurements are designed to measure all types of air contaminants, with no attempt to differentiate between naturally occurring contaminants and those that result from human activity.   Measurements of air quality fall into three classes: M easur asur ement of emissi emissi ons:    This is called stack sampling when a stationary

source is analyzed. Samples are drawn out through a hole or vent in the stack for on-the-spot analyses. Mobile sources like automobiles are tested by sampling exhaust emissions while the engine is running and working against a load. M eteorol teorol ogical meas measur ur ements:  ments:    The measurement of meteorological factors wind speed, wind direction, lapse rates, and so forth is necessary to determine how pollutants travel from source to recipient. M eas asur ur ement ment of ambient ambient air quali ty:    Ambient air quality is measured by a variety of monitors, which are discussed in th this is chapter. Almost all evidence of the health effects of air pollu pollution tion is based on correlation of these effects with measured ambient air quality.   Air

quality monitoring instrumentation has been developed in three phases.

  First-generation

devices    were developed

when little or n no o precedent existed for measuring very small quantities of gases in the atmosphere, nor was much money available for their development. Accordingly, they are simple, inexpensive, and usually do not require power to operate. They are also inconvenient, slow, and of questionable accuracy.   Second-generation measurement    equipment evolved when more accurate data and more rapid data collection were required. It uses power-driven  pumps and other collection devices, and can sample a larger volu volume me of air in a relatively short time. Gas measurement is usually by wet chemistry--that is, collected gas is either dissolved into or reacted with a collecting fluid. d-generati on de devices  vices    differ from their predecessors in that they provide   Th ir d-generati continuous readout. The m measurement easurement of pollutant concentrations is alm almost ost instantly translated by a readout device, so that the pollution may be measured while it is happening.

 

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  M EAS EASUREMENT UREMENT OF PART ARTII CULATE M ATTER ATTER::  

First-generation devices for measuring particulate matter measure how much dust settles to the ground. Such dust fall measurements are by far the simplest means of evaluating air quality, and can also indicate tthe he direction of the pollution qualitatively.   Dust is collected either in open buckets which can contain water to trap the dust, or on a sticky surface.   The second-generation particle sampling device, the high-volume sampler is a substantial improvement over the dust fall jar, and has become the workhorse of particle sa sampling. mpling. It operates much like a vac vacuum uum cleaner by pu pumping mping air at a high rate through a filter.   Air flow through the filter is measured with a flow meter, usually calibrated in cubic feet of air per minute. Because the filter fil ter collects dirt du during ring its hour of operation, less air passes through it during the latter part of the test than in the beginning, and the air flow must therefore be measured at the start and the end of the test period and th thee values averaged.   The high-volume high-volu me sampler operated in thi thiss wa way y measures ttotal otal suspended  particulate matter, or TSP, as distinguished from other measurements of  particulate matter.

 

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  M EAS EASUREM UREM ENT OF GASES GASES::  

Two of the most ingenious devices were developed to measure ozone   and SO2   and .   Oz Ozone one attacks  attack s    and cracks rubber. To me  and measure asure it, specially prepared and weighed strips of rubber are hung out of doors and the cracks formed in each strip are measured. The strips may be calibrated by exposure for certain periods of time to known ozone concentrati concentrations. ons.     Sulf ur dioxide 

may be measured by impregnating chemicals that react with SO2 and change color.

filter

papers

with

 

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  M eas asur ur eme ment nt of water water po poll lu tion:



  Quantitative

measurements of pollutants are obvi obviously ously n necessary ecessary before water pollution can be controlled. However, measurement of these pollutants is fraught with difficulties. Sometimes specific materials responsible for the  pollution are not known. Moreover, these pollutants are generally present at low concentrations, and very accurate methods meth ods of detection are rrequired. equired.   Many water pollutants are measured in terms of milligrams of the substance per liter of water (mg/L). In older publications pollutant concentrations are expressed as parts per million (ppm). olve ved d oxygen oxygen :   D i ssol   You

can't tell by looking at water that there is oxygen in it But, if you look at a closed bottle of a soft drink, you don't see the carbon dioxide dissolved in that until you shake it up and open the top. The oxygen dissolved in lakes, rivers, and oceans is crucial for the organisms and creatures living in it. As the amount of dissolved oxygen drops below normal levels in water bodies, the water quality is harmed and creatures begin to die off. Indeed, a water body can "die",

process called  called .    a Although water eutrophication  molecules contain

an oxygen atom, this oxygen is not what is needed by aquatic organisms living in our natural waters. A small amount of oxygen, up to about ten molecules of oxygen per million of water, is actually dissolved in water. This dissolved oxygen is breathed by fish and zooplankton and is needed by them to survive.   Rapidly moving water, such as in a mountain stream or large river, tends to contain a lot of dissolved oxygen, while stagnant water contains little. Bacteria in water can consume oxygen as organic matter decays. Thus, excess organic material in our lakes and rivers can cause an oxygen-deficient situation to occur. Aquatic life can have a hard time in stagnant water that has a lot of rotting, organic material in it, especially in summer, when dissolved-oxygen levels are at a seasonal low.

  Bi oche ochemi mi cal Oxygen Oxygen Demand:  

BOD is a measure of oxygen use, or potential pot ential oxygen use.   An effluent with  a high BOD may be harmful to a stream if the oxygen consumption is great enough to cause anaerobic conditions. Obviously, a small trickle going into a  great river will have negligible effect, regardless of the BOD concentration involved. Similarly, a large flow into a small stream may seriously affect the stream even though the BOD concentration might be low. 

 

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  Chemical Ox yg yge en De D emand:   Among

many drawbacks of the BOD test, the most important is that it takes five days to run. If the organic compounds are oxidized chemically instead of biologically, the test can be shortened consi considerably. derably.   Such oxidation is accomplished with the chemical oxygen demand (COD) test. Because nearly all organic compounds are oxidized in the COD test and only some are decomposed during the BOD test, COD values are always higher than BOD values.   Wate Waterr te tempe mperr atur e:   Water

temperature is not only important to swimmers and fisherman, but also to industries and even fish and algae.   A lot of water is used fo forr cooling purposes in power plants that generate electricity.   Temperature can affect the ability of water to hold oxygen as well as the ability of organisms to resist certain pollutants. 

  PH:   PH

is a measure of how acidic/basic water is.   The range goes from 0 - 14, with 7 being neutral.   PH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.   Water that has more free hydrogen ions is acidic, whereas water that has more free hydroxyl ions is basic.   Since pH can be affected by chemicals in the water, pH is an important indicator of water that is changing chemically.   Pollution can change water’s pH, which in turn can harm animals and plants living in the water.

 

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 

Measuring PH steps:  

The water sample is placed in the cup and the glass probe at the end of the retractable arm is placed in the water.   Inside the thin glass bulb at the end of the probe there are two electrodes that measure voltage.   One electrode is contained in a liquid that has a fixed acidity. The other

 

electrode responds to the acidity of the water sample. A voltmeter in the probe measures the difference between the voltages of the two electrodes. The meter then translates the voltage difference into pH and displays it on the little screen on the main box.

  Turbidity:  

Turbidity is a measure of the degree to which the water loses its transparency due to the presence of suspended particulates.   Material that causes water to be turbid include:

  Clay.   Silt.   Finely divided organic and inorganic matter.









colored organic compounds.    Soluble Microscopic organisms.



 

The WHO (World Health Organization), establishes that the turbidity of drinking water shouldn't be more than 5 NTU, and should ideally be below 1 NTU.   Turbidity is measured in N T U  : Nephelometric Turbidity Units.   In lakes the turbidity is measured with a secchi disk.   The unit used in the ancient times was JTU (Jackson Turbidity Units), measured with the Jackson candle turbidimeter. This unit is no longer in standard use.

 

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  Suspe Suspen n de ded d sedi sediment ment::  

Suspended sediment is the amount of soil moving along in a stream. It is highly dependent on the speed of the water flow, as fast-flowing water can pick up and suspend more soil than calm water. During storms, soil is washed from the stream  banks into the stream. The amount that washes into a stream depends on the type of land in the river's watershed river's  watershed and the vegetation surrounding the river.   If land is disturbed along a stream and protection measures are not taken, then excess sediment can harm the water quality of a stream. You've probably seen those short, plastic fences that builders put up on the edges of the property they are developing. These  These silt fences are supposed to trap sediment during a rainstorm and keep it from washing into a stream, as excess as  excess sediment can harm the creeks, rivers, lakes, and reservoirs.  reservoirs.     Sediment coming into a reservoir is always a concern; once it enters it cannot get out - most of it will settle to the bottom. Reservoirs can "silt in" if too much sediment enters them. The volume of the reservoir is reduced, resulting in less area for boating, fishing, and recreation, as well as reducing the power-generation capability of the power the power plant in the dam. dam.  

 

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References: http://www.lenntech.com/turbidity.htm. http://ga.water.usgs.gov/edu/characteristics.html. En vir onmental onmental Poll uti on and Control , 4th 4th editi editi on bookmark bookmark ed.