البحث 2012- 6-17

1. University of
sulaimani
School of science
Chemistry
department
Determination of Heavy Metals In Wastewaters
Prepared by
Aram I. Abdul Rahman
Mustafa Hassan
Date 16-Jun-2012

2. CONTENTS
 Waste water
 Heavy metal
 Heavy metal toxicity
 Effect of Heavy Metals on Health and
Environment
 Methods for Removing Heavy Metals from
Waste Water
 Methods for the determination of heavy
metals

3. WASTE WATER
 Wastewater is water containing waste, or water
that has been in contact with waste material.
Waste includes any material that is dissolved,
suspended or transported in water. It includes
substances such as human waste, food scraps,
oils, soaps and chemicals. In homes, this
includes water from sinks, showers, bathtubs,
toilets, washing machines and dishwashers.
Businesses and industries also contribute their
share of used water that must be cleaned.

4. TYPES OF WASTE WATER
 Domestic wastewater
(includes household waste from washing, bathing, toilets)
 Biodegradable industrial wastewater
(contains a high concentration of organic waste arising from industrial
activities and premises . Biodegradable industrial wastewater is
generated by activities such as: Manufacturing and bottling of soft drinks
and water bottling, Production of alcoholic beverages in breweries )
 Industrial wastewater
( Industrial wastewater is generated by a wide range of
activities such as: Chemical industries, Metal plating, Plastics,
Leather processing, Pulp and paper manufacture.)

5. HEAVY METALS
 Heavy metals are the non- degradable metals .These metals are
toxic and possess high density.
 Heavy metals occur in the earth’s crust naturally. Some of the
heavy metals are lead, cadmium, mercury, arsenic, chromium and
thallium. High concentration of heavy metals causes poisoning.
 Heavy metal causes severe water pollution
 Heavy metals are dangerous because they tend to bio
accumulate. Bioaccumulation means an increase in the
concentration of a chemical in a biological organism over time,
compared to the chemical's concentration in the environment.
 Heavy metals are also common in industrial applications such as
in the manufacture of pesticides, batteries, alloys, electroplated
metal parts, textile dyes, steel

6.  Heavy metals can enter a water supply by industrial and
consumer waste, or even from acidic rain breaking down
soils and releasing heavy metals into streams, lakes,
rivers, and ground water
 SOURCES OF HEAVY METALS
 The main sources of heavy metal are weathering of
rocks and volcanic eruption in which metals are released
in water sources.
 Other sources are:-
* Domestic waste water and urban run-off
* Industrial waste water
* Agricultural activities
* Mining activities

8. HEAVY METAL TOXICITY
 Heavy metals are toxic to human health. Most
common heavy metals are lead, mercury, cadmium,
arsenic, antimony, bismuth, chromium, iron,
manganese, nickel, platinum, silver, thallium, tin,
uranium, vanadium, and zinc. Interestingly, small
amounts of these elements are common in our
environment and diet and are actually necessary for
good health, but large amounts of any of them may
cause acute or chronic toxicity (poisoning). Heavy
metal toxicity can result in damaged or reduced
mental and central nervous function, lower energy
levels, and damage to blood composition, lungs,
kidneys, liver, and other vital organs.

9. THE MOST COMMONLY ENCOUNTERED TOXIC
HEAVY METALS INCLUDE
 Arsenic
 Lead
 Mercury
 Cadmium
 Iron
 Aluminum

10. LEAD
 Health effects of lead
 At high levels, inorganic lead is a general
metabolic poison
 Lead poisoning effects the neurological and
reproductive systems
 Environmental effects of lead
 Lead accumulates in the bodies of water
organisms and soil organisms

11. METHODS FOR REMOVING HEAVY METALS FROM WASTE WATER
 Chemical Precipitation
Chemical precipitation is the most common
technology used to remove dissolved (ionic) metals
from water solutions, such as process waste waters
containing toxic metals. The ionic metals are
converted to an insoluble form (particle) by the
chemical reaction between the soluble metal
compounds and the precipitating reagent. Typically,
the metal precipitated from the solution is in the form
of hydroxide. The conceptual mechanism of heavy
metal removal by chemical precipitation is
represented as

12.  where M(OH)n is insoluble metal hydroxide and
Mn+ and OH- represent dissolved metal ions and
precipitant, respectively. Therefore, the optimum
pH for precipitation of one metal may cause
another metal to solubilize, or start to go back into
solution.
 Most process waste waters contain mixed metals
and hence precipitating these different metals as
hydroxides can be a tricky process. Chemical
precipitation requires large amounts of chemicals
to reduce the concentration of metals to an
acceptable level for discharging waste waters into
the environment.

13. ION EXCHANGE
 Ion exchange is a reversible chemical reaction wherein an ion
present in solution is exchanged with a similarly charged ion
bound to a stationary solid phase (resin). Ion exchange can
also be used for recovering valuable heavy metals from
inorganic effluents. After separating the loaded resin, metals
 Can be recovered in a more concentrated solution by eluting
with suitable reagents.
 Since the acidic functional groups of the resins consist of
sulfonic acid,
 It is assumed that the physico-chemical interactions occurring
during metal removal can be expressed as follows:

14. Electrochemical Treatment Techniques
Electro-dialysis (ED) is a membrane separation technique in
which ionized species in the solution are passed through an
ion-exchange membrane by applying an electric potential. The
membranes are thin sheets of plastic materials with either
anionic or cationic charge. When a solution containing ionic
species passes through the cell compartments, the anions
migrate toward the anode and the cations migrate toward the
cathode, crossing the anion-exchange and cation-exchange
membranes. Since ED is a membrane process, it requires
clean feed, careful operation, and periodic maintenance to
prevent any damage to the membranes. In conclusion,

15. REMOVAL OF HEAVY METALS FROM INDUSTRIAL WASTEWATERS BY
ADSORPTION ONTO ACTIVATED CARBON PREPARED FROM AN
AGRICULTURAL SOLID WASTE
 Activated carbon was prepared from coir pith by a
chemical activation method and characterized. The
adsorption of toxic heavy metals, Hg(II), Pb(II), Cd(II),
Ni(II), and Cu(II) was studied using synthetic solutions
and was reported else
 where. In the present work the adsorption of toxic heavy
metals from industrial wastewaters onto coir pith carbon
was studied. The percent adsorption increased with
increase in pH from 2 to 6 and remained constant up to
10. As coir pith is discarded as waste from coir
processing industries, the resulting carbon is expected to
be an economical product for the removal of toxic heavy
metals from industrial wastewaters.

16. METHOD FOR THE DETERMINATION OF HEAVY METALS
 Atomic absorption
 Atomic emission ICP
 Chromatography
 Voltammetery

17. METHODS USING ION CHROMATOGRAPHY
 Ion chromatography is known to be a promising
method for the analysis of natural water.
It is the best method of determining anions in 
aqueous solutions. The method is also suitable
for determining heavy metals.
 Highly sensitive dual—column techniques have
been developed to determine metals in different
types of water, with the separation according to
both the cation— and the anion—exchange
mechanism.

18.  In the first case Cd, Cu, Mn, Ni, Pb, Sr and Zn have
been separated by elution with ethylenediammonium
chloride or ethylendiammonium tartrate solutions and
determined with a conductometric detector.
 When determinations are made by the anion—exchange
mechanism, the metals (As, Cr, Mo, Se,Te, V and W) are
first converted into oxoanions, and the separation is
conducted on columns with "Dionex" low—capacity
anion—exchange resin; the elution is performed with
sodium carbonate

19. REFERENCES
 http://www.cbc.ca/manitoba/features/lakewinnipeg/wastewat
er.html
 B.V. L’vov (2005), Fifty years of atomic absorption
spectrometry; J. Anal. Chem., 60: 382–392.
 http://www.cbc.ca/manitoba/features/lakewinnipeg/checkup.
html
 http://www.tip2000.com/health/waterpollution.asp