enviromental pollution

Lesson 1. Natural and contaminated water characteriza2on

1.1. Issue descrip2on.

1.2. Characteris2cs of the natural water.

1.3. Characteris2cs and parameters of the contaminated water.

1.3.1. Physical contaminants.

1.3.2. Chemical contaminants.

1.3.3. Biological contaminants.

Unit 1 Environmental Technology

1.1 Issue Descrip0on


More than % of the water is on the oceans and is not usable.

From the % usable, almost % is ice or water vapor.

As a result, only % of the water can be used be humans (8.4 km3).

Water is also the main cons2tuent of the living organisms

-‐ Adipose 2ssue %

-‐ Heart, liver… %

-‐ Nervous 2ssue %

Of food:

-‐ Fruits and vegetables %

-‐ Fish %

-‐ Meat %


Humans need L/day

But potable water needed is small compared with domes2c, industrial and agricultural water. From the world water consump2on:

-‐ % is for domes2c use

-‐  % industrial and commercial uses

-‐  % agricultural and caWle uses

1 Tn paper needs Tn water

1 Tn preserved vegetables Tn water

1 car Tn water

1 Tn corn 1000 Tn water, 1 Tn wheat 1500 Tn water, 1 Tn coWon 10000 Tn water


Hydrologic Cycle

It is the cycle by which the amount of water in the earth is keeping constant due to the and

.

The cycle starts with the water evapora2on and later precipita2on ( km3/year). Only % of this water falls into the con2nents. From this, % is again evaporated and % is transferred to runoff.

Over the ocean, the evapora2on is than the precipita2ons ( %). This percentage is balanced over the con2nents where is higher than

( %).


Human ac2ons have impact into the water cycle

-‐ Contamina2on can be to .

-‐ Atmosphere and soil may have an impact to the quality of the water.

For the first 2me, humans

know about importance of water disinfec2on.

H2O: bonds between H and O (100 kcal/mol). (molecular) bonds between H and O from different molecules (5 kcal/mol). Hydrogen bonds are formed because of the high of oxygen that aWracts electric density. Hydrogen bonds are very important because give water its important characteris2cs and is fundamental for life. Hydrogen bonds give water unexpected mel2ng and evapora2on high points. Hydrogen bonds cause ice has smaller than water and that during winter the water is only solid over the surface. Life can con2nue below ice.

1.2. Characteris0cs of the natural water.



When temperature is incremented, hydrogen bonds start to be broken but several bonds keep on liquid water. Density decrease with temperature because more hydrogen bonds are broken. This causes that the specific heat of water is high (the amount of heat to increase 1 °C 1 g of water).

High mel2ng, vaporiza2on heats and specific heats cause water works as a perfect and controls earth temperature between precise limits.

Raining water adds gases (Nitrogen, oxygen, CO2), has pH slightly low (5.7) and when runs in rivers dissolves salts (low mineraliza2on).

Differences between runoff and underground water


Natural water contents because of its and poten2al. These substances are in suspension, in dilu2on, or in colloid.

-‐ : atmosphere (CO2, N2, O2), products of the living organisms metabolism (CO2, O2), aerobic and anaerobic decomposi2on (CO2, CH4, H2S, N2).

-‐ : material dissolu2on (Ca2+, Na+, Mg2+, etc.), anions (HCO3-‐, SO4

2-‐, NO3-‐,

etc.), material decomposi2on (PO43-‐, NO3

-‐, NH4+, etc.).

-‐ : sand, clay.

-‐ : amino acids, faWy acids, natural pigments, etc.


Water pollu2on: Water is contaminated when its or is altered directly or indirectly as a consequence of the human

ac2vity. As a result, this modified water can’t be used with the same purpose than the natural water.

Consequences:

-‐ Contamina2on is measured as a .

-‐ Contamina2on is directly or indirectly generated by the humans.

1.3. Characteris0cs and parameters of the contaminated water


Total maWer: is composed by maWer in .

MaWer is suspension is the main responsible of:

-‐  Colour, reduc2on of the sunlight that reach water under the surface, sediment deposi2on.

Substances that can be removed by filtra2on are responsible of:

-‐ Salinity, O2 solubility, toxicity.

Some quan2fiable magnitudes:

-‐ (MS) or (SS).

-‐ (DR) at 105 ºC o total dissolved solids (TDS).

-‐ Fixed residue.

1.3.1. Physical contaminants


Odour: contaminated water has a characteris2c odour due to the decomposi2on of the organic maWer.


hWp://extoxnet.orst.edu/faqs/safedrink/colors.htm

Colour: the possible reason is the presence of organic and inorganic compounds. These compounds could be or .

Urban wastewater: grey colour (recent wastewater), black colour (microorganisms have decomposed the waste).

Industrial wastewater: different colours depending on the contaminant

Temperature: it has a great influence into water quality

-‐ gases solubility (O2).

-‐  microorganism ac2vi2es (kine2c of the reac2on).

Both consequences are combined and the effect of the other.

-‐  the prolifera2on of water organism (plants and fungus).


Organic Chemical contaminants: Organic MaWer (O.M.). Biodegradability.

The source could be natural or urban/industrial.

Natural source: from plants and animals . Biodegradable.

Urban/industrial source: Organic chemical products. Biodegradable and not biodegradable.

Examples:

Detergents: (surfactant) and .

Ac2ve ingredients (10-‐15%): surfactants. crea2on and oxygen demand because they are organic compounds.

Co-‐Adjuvants: an2-‐calcareous (poli-‐phosphates, zeolites, carbonates, etc.).

Addi2ves: bleaching agent (perborates, NaClO), an2foam agent, etc.

1.3.2. Chemical contaminants


Pes2cides: chemical products used to in agriculture, caWle, pets…, etc. Formula2on: ac2ve agent + other substances.

Inorganic and organic (more used) pes2cides:

-‐ Chlorinated hydrocarbons (DDT, chlorobenzene).

-‐  Organophosphates.

-‐  Carbamates

hWps://www.youtube.com/watch?v=Ipbc-‐6IvMQI

Polychlorinated biphenyl (PCBs): are ; not flammable; low electric conduc2vity; acid, basic and oxidant resistance, etc. They are high inert and because of this they are persistent and bio-‐accumula2ve. Can produce or increment halogenated levels.


Hydrocarbons: saturated hydrocarbons (alkanes), unsaturated (olefin), cycloalkanes and aroma2c compounds.

General characteris2cs: solubility in water, density than water and biodegradability.

Regarding contamina2on:

-‐ the oxygen dissolved. Superior organisms need 2 mg O2/L in water.

Usually, superficial water (T=25 C) is oxygen ( mg O2/L)

-‐ May be toxic.

-‐ Because their density and solubility, hydrocarbons create one layer on water surface that light pass and oxygen diffusion through it.


There are μorganisms in water and when there are organic maWer:

-‐ process. Products are CO2, NO3-‐, SO4

2-‐, H2O. Stable and rela2vely inert products.

But when there is high amount of organic compounds, O2 is consumed and:

-‐  process: Hydrogen sulphur, CH4, NH3, amines… No stable and undesirable.


Parameters for the evalua2on of the organic contamina2on:

-‐  Biochemical oxygen demand (BOD, mgO2/L).

-‐  Chemical Oxygen demand (COD, mgO2/L).

-‐  Total Organic Carbon (TOC, mgC/L).

-‐  Total Oxygen Demand (TOD, mgO2/L).

Biochemical oxygen demand: is the amount of oxygen consumed by microorganism in the of the organic maWer under condi2ons. This magnitude gives the amount of oxygen necessary to biologically stabilize the organic maWer (O.M.) in water.

O.M. + O2 + + microorg. è CO2 + H2O + ( .)


Because is a biological process, it is slow.

BOD5, a t = 5 days. BOD20, t = 20 days.

Standard values:

High pure waters, BOD5 < 3 mgO2/L.

Contaminated water. BOD5 > 8 mgO2/L.

Urban wastewater, BOD5 100 – 400 mgO2/L.

Agrifood industry wastewater, BOD5 10.000 mgO2/L.

Limita2ons:

-‐ Very slow analysis (at least 5 days).

-‐ Only determines maWer

-‐ It’s necessary to do pre-‐treatments (impacts on microorg. and nitrifica2on).


Chemical Oxygen Demand: is the amount of oxygen consumed by in the organic maWer degrada2on. With this magnitude it is

measured all the organic maWer (biodegradable and not) and the inorganic maWer that can be degradable by oxida2on.

COD BOD

M.O. + Cr2O72-‐ + 8 H+ è CO2 + H2O + 2 Cr3+ (2h, 140 ºC)

M.O. + MnO4-‐ + H+ è CO2 + H2O + MnO2 (4h, 30 ºC)

Limita2ons:

-‐  It is not specific, and measures O.M.b, O.M.nb y M.I.

-‐  It is not precise.

Advantages: in 2h it’s possible to get informa2on about the O.M.


Informa0on from the rela0on BOD5/COD:

-‐  Biodegradability

values close to , wastewater with high biodegradability

values close to , wastewater with low biodegradability

-‐  Type of water

0,4 – 0,8, wastewater from urban sources

< 0,2, wastewater from industrial sources


Inorganic chemical contaminants They are important in the case of wastewater from sources.

General parameters indicators of the contamina2on:

Turbidity: Interference to the light passing through the water. The responsible of turbidity are: insoluble, in suspension, or in dispersion maWer.

It is measured in Turbidity Units.

hWp://www.lenntech.com/turbidity.htm

Conduc2vity: it’s the ability, in this case of the water, to conduct the electricity. It depends on the concentra2on of ions in water.

Hardness: it mainly depends on the concentra2ons of Ca2+ and Mg2+.

Concentra2ons of Fe2+ and Mn2+ have lower influence.

hardness: sum of Ca2+ and Mg2+ carbonates. Can be removed by hea2ng.

hardness: The hardness caused by calcium (and magnesium) salts (different from carbonates) It is not affected by hea2ng and is therefore called permanent hardness.


The reac2on

CaCO3 (s) + H2O(l) + (aq)

⇌ Ca2+(aq) + 2 (aq) ∆H (exot)

is in the forward direc2on, and Le Chatelier's principle predicts that at high temperatures, the equilibrium will move to the leu.

This is what happens inside keWles, dishwashers and washing machines and results in the forma2on of a deposit of on their hea2ng elements, Figure. This is usually called in everyday language. reduces heat transfer from the element to the water and makes the appliance less efficient.


Alkalinity: It is defined as the amount of ions present in water that react with H+ to neutralize them. It’s due mainly to . The main problem related with alkalinity is that these anions can react with ca2ons, precipitate and obstruct tubes.

It’s determined by the number of equivalents used for its . Three reac2ons and a valoriza2on curve is obtained:


pH=8.3 phenolphthalein

pH=4.5 Methyl Orange pH=8.3, OH-‐ neutraliza2on

and CO32-‐ to HCO3

-‐

pH=4.5, HCO3

-‐ to CO32-‐

Half of the H+ needed for the CO32-‐ neutraliza2on are added at pH=8.3

pH: magnitude used to express the and .

pH = -‐log[H+], in aqueous solu2on is between 0 y 14.

Acidity: it’s related with the capacity of water to absorb hydroxyls (OH-‐).

Alkalinity: it’s related with the capacity of water to absorb protons (H+).

It’s important to know the tendency of the water to form calcareous encrusta2ons.

Nitrogen and phosphorus: are of the biologic processes. Can be considered as contaminants when their concentra2on allow growing ( ).

Nitrogen comes from (agriculture and caWle) and phosphorous comes from . Algae consume oxygen when dye and decompose.

Algae growing is limited by nitrogen on waters and by phosphorous on waters. But human ac2vity removes this limita2on.


Nitrogen can be found as organic nitrogen, NH3/NH4+, NO3

-‐ y NO2-‐.

Phosphorous as organic-‐P, PO43-‐ and polyphosphate

Nitrogen may be present in water as: organic nitrogen, NH3, NO2-‐, NO3

-‐.

Nitrifica2on (oxida2on): Nitrifica2on is the biological oxida2on of or ammonium to nitrite followed by the oxida2on of the to .

-‐  Organic Nitrogen to ammonia by ammonifica2on or mineraliza2on.

-‐  NH3 + O2 → NO2− + 3H+ + 2e−

-‐  NO2− + H2O → NO3− + 2H+ + 2e−


Heavy metals: Apart from alkaline and alkaline earth metals, all metals are heavy. Some are in high concentra2ons (Fe3+, Al3+) and others in trace levels (Hg2+) in contaminated waters.

They are persistent and enter into the food chain.

hWps://www.youtube.com/watch?v=18s89XTyAl8

Pb (< 0,5 mg/dm3): baWeries, gasoline, pipes. Nervous system and kidney damages. Anaemia.

Hg (< 0,01 mg/dm3): electric devices, paints. Nervous system and kidney .

Cd (< 0,2 mg/dm3)


SUMMARY

Rela2ve amounts of analyzed parameters. “Wastewater quality”

Parameter Rela2ve amount (%)

pH 6

Solids in suspension 12

O.M. (BOD, COD, TOC) 15

Nitrogen 15

Phosphorous 6

Metals 30

Others 16

100


Biological contaminants: Part of the organic maWer in wastewater is formed by macroscopic and microscopic organisms.

Simplifying, organisms can be classified as: animal, vegetal and pro2st. Regarding water treatment pro2sts are the most important organisms. They are unicellular o pluricellular without differen2ated 2ssues (a cellular organiza2onal level intermediate between cells and a complete organism):

-‐  : food: O.M., oxygen and water. Heterotrophic (consume organic C) and autotrophic (get C cellular from CO2). Heterotrophic can be aerobic, anaerobic and faculta2ve anaerobic.

-‐  : eutrophica2on.

-‐  : parasites. They don’t have a principal role in the water depura2on.


Biological contamina2on indicators:

Coliform bacteria. They are in animal and human intes2nes. Indicator of the fecal contamina2on.

Bio2c indexes. Microorganisms determina2on in water.

Toxicity essays. With aqua2c organisms (e.g., Daphnia Magna). It measures the response of these aqua2c organisms to the presence of specific substances, residues, or isolated or combined environmental factors.

hWp://www.nature.com/news/specials/water/index.html


enviromental pollution

Documents

tn water unit

water evapora2on

agricultural water

potable water

g of water

water vapor

liquid water

vegetables tn water