Water quality analysis
&
Waste water treatment

• Water quality
• is the physical, chemical and biological characteristics of
water
• It is a measure of the condition of water relative
• to the requirements of one or more biotic species
• to any human need or purpose

Physical parameters
• The commonly measured physical characteristics
are temperature, colour, taste, odour and turbidity.

The parameters used to assess the quality of
water can be:
• Physical
• Chemical
• Biological
Water quality parameters

Physical parameters
◼ Color
◼ Odor
◼ Temperature
◼ Turbidity
◼ Solids
◼TSS
◼TDS

• Turbidity is a measure of the degree to which the water loses
its transparency due to the presence of suspended
particulates.
• Cause:
• Phytoplankton
• Sediments from erosion
• Resuspended sediments from the bottom
• Waste discharge
• Algae growth
• Urban runoff
• turbidity of drinking water -should ideally be below 1 NTU
-shouldn't be more than 5 NTU
(Nephelometric Turbidity Units)

• TSS - Total suspended solids
• is a measure of the amount of sediment moving along in a
stream.
• Suspended solids cause the water to be milky or muddy looking
due to the light scattering from very small particles in the water.
• TDS - Total Dissolved Solids
• a measure of all the inorganic and organic substances contained
in a liquid
• that may be in molecular, ionized or micro-granular (colloidal sol) suspended
form
• expressed in units of mg per unit volume of water (mg/L)
• "Dissolved solids" refer to any minerals, salts, metals, cations or
anions dissolved in water.
• the most common chemical constituents are calcium, phosphates, nitrates,
sodium, potassium and chloride

Chemical parameters
• pH
• BOD
• COD
• DO
• N, P,

• pH
• pH is a term used to indicate the alkalinity or acidity of a
substance
• ranked on a scale from 1.0 to 14.0.
• it is caused by the balance of positive hydrogen ions (H+)
and negative hydroxide ions (OH-) in water.

• DO - Dissolved oxygen
• is a relative measure of the amount of oxygen that is dissolved
or carried in a given medium
• (Oxygen saturation)
• Oxygen gets into water by diffusion from the surrounding air,
by aeration and through photosynthesis.
• Depletions in dissolved oxygen can cause major shifts in the
kinds of aquatic organisms found in water bodies

BOD – Biochemical Oxygen Demand (mg/l)
• The quantity of oxygen (O2) that microorganism use per
litre water, during a continuous period of 5 days, at 20°C.
• The rate at which organisms use the oxygen in wastewater
while stabilising decomposable organic matter under
aerobic conditions.
COD – Chemical Oxygen Demand (mg/l)
• A measure of the oxygen-consuming capacity of organic
matter present in wastewater.
• COD is expressed as the amount of oxygen consumed from
a chemical oxidant (K2Cr2O7 ) in mg/L during a specific test.

• Domestic wastewater: BOD/COD = 0.4
• Dairy wastewater: BOD/COD = 0.6 – 0.7
• BOD5/COD > 0.6 biodegradable
• BOD5/COD < 0.2 non-biodegradable,
recalcitrant

• Alkalinity
• a total measure of the substances in water that have “acid-
neutralizing” ability sources: mineral dissolved in water and air
• detergent (in wastewater), fertilizers, pesticide, so forth.
• Hardness
• a measure of multi-valent cations in water such as Ca2+, Mg2+,
Fe2+, Mn3+.
• Ca2+ and Mg2+ are very important and usually present in water.
Two kinds of hardness:
• Carbonate hardness: due to Ca(HCO3)2 and Mg(HCO3)2
• Temporary
• precipitated through heating
• Non-Carbonate hardness: due to CaCl2, CaSO4, MgCl2, MgSO4;
• Permanent
• eliminated through chemical softness method or ion exchange.

• Inorganic Compounds
• will dissociate into an electrically charged atoms referred as ions and
classified as metal or non-metal.
• Metal Inorganic Compounds:
• Non-toxic Metal
• Na+, Ca2+, Mg2+, Fe2+, Mn2+, Cu2+, Zn2+, Al3+. - dangerous if the
concentration is high
• Toxic Metal
• Normally it is stored in the food chain, such as As2+, Ba2+, Cd2+, Cr2+, Pb2+,
Hg2+.
• source : through mining and industries
• Non-Metal Inorganic Compounds:
• Source: mineral such as Si4+, Cl-, NO3-.
• Organic Compounds
• Sources: fibers, vegetable, animal oils and fats, cellulose, starch, and
sugar.
• manufacturing processes such as polyvinylchloride and DDT.
• Fermentation of alcohols, acetone, glycerol, antibiotics, acids, etc.
• THM- Trihalomethane – a carcinogenic compound produced in water and
waste-water treatment plants.

Biological parameters
• Coliform
• Pathogen
• CFU
• Type of microorganisms
• Bacteria
• Virus
• Algae
• Fungi
• Protozoans

Biological characteristics

• A number of pathogenic microorganisms are transmitted
through contaminated water.
• Coliform bacteria are part of the Enterobacteriaceae family
• some coliform bacteria can be naturally found in soil
• the type of coliform bacteria that lives in the intestinal tract of warm-
blooded animals and originates from animal and human waste is called
fecal coliform bacteria.
• Escherichia coli (E. coli) is one subgroup of fecal coliform bacteria. Even
within this species, there are numerous different strains, some of
which can be harmful.
• E. coli strain named 0157:H7 that lives in the intestinal tract of cattle is
pathogenic. This strain is primarily spread to people by eating
contaminated, undercooked beef or drinking unpasteurized milk and is
not generally found in surface waters
• other pathogens of fecal origin that are health threats include
Salmonella, Shigella, and Psuedomonas aeruginosa.
• Non-bacterial pathogens that may be present with fecal
material include protozoans, such as Cryptosporidium and
Giardia, and viruses.

WATERBORNE DISEASES
Diseases Responsible pathogen
Route of
exposure Mode of transmission
Cholera Vibrio cholerae
bacteria
gastro-
intestinal
often waterborne
Botulism Clostridium botulinum
bacteria
gastro-
intestinal
food/water borne; can grow
in food
Typhoid Salmonella typhi
bacteria
gastro-
intestinal
water/food borne
Hepatitis A Hepatitis A virus gastro-
intestinal
water/food borne
Dysentery Shigella dysenteriae
bacteria or
Entamoeba histolytica
amoeba
gastro-
intestinal
food/water
Cryptosporidiosis Cryptosporidium
parvum protozoa
gastro-
intestinal
waterborne; resists chlorine
Polio polioviruses gastro-
intestinal
exposure to untreated
sewage; may also be
waterborne
Giardia Giardia lamblia
protozoa
gastro-
intestinal
waterborne

Wastewater treatment

Wastewater treatment: principles
microbes
• pollution biomass breakdown products
(sludge)
• aerobic (with oxygen)
• anaerobic (without oxygen)

Levels of Treatment
• Primary
• Secondary
• Tertiary

Primary treatment
• the physical process of sedimentation to remove
settleable suspended solids from wastewater
• removal of grit and large objects
• (material to landfill for disposal)

Secondary treatment
• biological treatment to remove dissolved and fine
suspended organic matter from wastewater.
• the removal of
• Biodegradable organics
• Total suspended solids
• Pathogens

Secondary treatment
◼ aerobic microbiological process (sludge)
organic matter + O2 → CO2 + NH3 + H2O
NH3 → NO3
-
- lowers suspended solids content (into sludge)
aquatic nutrient
Mostly dead
microbes

Aeration
and rapid
mixing
Settling
collects sludge
on bottom
Secondary process
air
diffuser
From
primary
process
To
tertiary
process

Nitrogen removal
• proteins
• ammonia-N
• nitrate-N
• N2 gas

Phosphorus removal
• Phosphorus precipitation:
• iron, calcium, aluminium

Removal mechanisms
• Suspended solids Sedimentation/Filtration
Microbial degradation
(aerobic, anaerobic)
Sedimentation
• Nitrogen Ammonification, nitrification,
denitrification, Plant uptake
Ammonia volatilization
• Phosphorus Soil sorption (adsorption-precipitation
reactions with Fe, Al, Ca), Plant uptake
• Pathogens Sedimentation/Filtration
Natural die-off
UV radiation

Tertiary treatment (advanced)
• biological or physico-chemical treatment processes to
remove water contaminants not removed by primary and
secondary treatment, such as nutrients, toxic materials or
additional suspended solids and BOD removal.

Tertiary (advanced)
• anaerobic microbiological process with a different microbe
where O2 is toxic (more sludge)
NO3
- → N2 (escapes to atmosphere)
• PO4
-3 if not removed in sludge in secondary process
PO4
-3 + Al+3 → AlPO4 (s) (into sludge)
- aeration to strip N2 and re-oxygenate (add DO)

• Carbon
• is a substance used to absorb impurities
• is a most powerful absorbent
• Activated carbon
• is carbon which has a slight electro-positive charge added to it
• Makes it even more attractive to chemicals and impurities.
• As the water passes over the positively charged carbon surface, the
negative ions of the contaminants are drawn to the surface of the
carbon granules.

• Disinfection - the final step in the treatment process
• is designed to kill pathogenic bacteria and viruses
• commonly done by chlorination
• with chlorine gas or hypochlorite.
Disadvantage:
• by-products chlorinated hydrocarbons
• are toxic and difficult to mineralize
• Ozonation an alternative to chlorination
• uses ozone as the oxidant.

When the treatment is done…
• Effluent back to stream after
• a final carbon filtration and
• chlorination/dechlorination
• Sludge – very nutrient rich
• applied directly to land as fertilizer
• incinerated (good fuel after drying)
• composted