how turbidity in the water is measured and what is its principle ? how electrical conductivity is measured and what is its principle ? how total dissolved solids are determined in a liquid and what is its principle ? how total suspended solids are determined in a liquid and what is its principle ?

1. IIUI INTERNATIONAL ISLAMIC UIVERSITY ISLAMABAD
PRESENTED BY: Mahboobullah
PRESENTED TO: Sir Islamuddin
principles of physical
Analysis

2. Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of
individual particles that are generally invisible to the naked eye, similar
to smoke in air. The measurement of turbidity is a key test of water quality.
Fluids can contain suspended solid matter consisting of particles of many different
sizes. While some suspended material will be large enough and heavy enough to
settle rapidly to the bottom of the container if a liquid sample is left to stand
(the settable solids), very small particles will settle only very slowly or not at all
if the sample is regularly agitated or the particles are colloidal. These small solid
particles cause the liquid to appear turbid.
Turbidity Analyzer Working Principle
Turbidity is an optical property of water based on the amount of light scattered and
absorbed by colloidal and suspended particles. The turbidity value measured in
FNU, FTU, NTU etc. is the quantitative statement of this qualitative
phenomenon.Nephelometry means that the light source and the photodetector are
set at a 90-degree angle from each other. This is considered the angle most
sensitive to light scatter regardless of particle size

3. Nephelometry Turbidity Analyzer Principle
The goal of measuring turbidity is to get an indication for the concentration of
scattering particles in a medium. This can be done by determination of the light
loss of the transmitted beam or the measurement of the light scattered sideways.
Both methods deliver proportional data to particle concentration and are therefore
suitable for measuring turbidity. They however differ in application and
concentration levels. Scattered light measurement principle is more suitable for
the detection of lower concentrations, while transmission (reflection or
absorption) measurement is used for higher concentrations.
Turbidity Analyzer Working Principle
The device measures scatted light at 90°
which is according to ISO 7027 / DIN EN
27027 to be used for turbidity values
below 40 NTU The NIR light source and
receiver are positioned in a 90° angle to
each other. The light transmitted from
the source is directed in equal strength to the reference detector and into the
medium. Light is scattered from the particles and the portion which is scattered
at a 90° angle is received by the detector. The meter now compares the light from
the reference detector and scattered light receiver and calculates the turbidity
value.
The measurement unit for the turbidity measured at a 90° angle varies depending
on country in and is according to ISO 7027 Formazine Nephelometric Unit (FNU),
but the more commonly used terminology is Nephelometric Turbidity Unit (NTU)
stated within the US EPA 180.1. Both units compare 1 to 1.
The advantage of the using NIR as light source as stated in the ISO 7027 is that this
sensor is not affected by color of the medium measured.

4. Electrical conductivity
Electrical Conductivity-Principle of its Measurement. Electrical Conductivity is
a measure of the ability of a substance/solution to conduct an Electric Current
(this electric current is carried by ions and the chemical changes that occur in the
solution
Electrical conductivity measurement principle
Conductive measurement
Contacting conductivity Contacting conductivity uses a cell with two metal or
graphite electrodes in contact with the electrolyte solution. An AC current is
applied to the electrodes by the conductivity meter, and the resulting AC voltage.
This technique can measure down to pure water conductivity. Its main drawback
is that the cell is susceptible to coating and corrosion, which drastically decreases
the reading. In strongly conductive solutions there can also be polarization effects,
which result in non-linearity of measurements.
Inductive measurement
It is made by passing an AC current through a toroidal drive coil, which induces a
current in the electrolyte solution, see figure below. This induced solution current,
in turn, induces a current in a second toroidal coil, called the pick-up toroid. The
amount of current induced in the pick-up toroid is proportional to the solution
conductivity. Sample Input AC voltage Drive coil Pick-up coil Induced current
dependent on the conductivity of the sample Current field The main advantage of
toroidal conductivity is that the toroidal coils are not in contact with the solution.
They are either encased in a polymeric material or are external to a flow through
cell. One of the main disadvantages of toroidal conductivity measurements is that
it lacks the sensitivity of contacting measurement. Toroidal sensors are also
typically larger than contacting sensors, and the solution current induced by the
toroid occupies a volume around the sensor. Hence, toroidal sensors need to be
mounted in a larger pipe.

5. Total dissolved solids (TDS)
Total dissolved solids (TDS) is a measure of the dissolved combined content of
all inorganic and organic substances present in a liquid in molecular, ionized, or
micro-granular (colloidal sol) suspended form. TDS is sometimes referred to as
parts per million (ppm)[1]. You can test water quality levels using a digital TDS PPM
meter[2].
Generally, the operational definition is that the solids must be small enough to
survive filtration through a filter with 2-micrometer (nominal size, or smaller)
pores. Total dissolved solids are normally discussed only for freshwater systems,
as salinity includes some of the ions constituting the definition of TDS. The
principal application of TDS is in the study of water quality for streams, rivers,
and lakes. Although TDS is not generally considered a primary pollutant (e.g. it is
not deemed to be associated with health effects), it is used as an indication of
aesthetic characteristics of drinking water and as an aggregate indicator of the
presence of a broad array of chemical contaminants.
Primary sources for TDS in receiving waters are agricultural runoff and residential
(urban) runoff, clay-rich mountain waters, leaching of soil contamination,
and point source water pollution discharge from industrial or sewage
treatment plants. The most common chemical constituents
are calcium, phosphates, nitrates, sodium, potassium, and chloride, which are
found in nutrient runoff, general stormwater runoff and runoff from snowy
climates where road de-icing salts are applied. The chemicals may
be cations, anions, molecules or agglomerations on the order of one thousand or
fewer molecules, so long as a soluble micro-granule is formed. More exotic and
harmful elements of TDS are pesticides arising from surface runoff. Certain
naturally occurring total dissolved solids arise from the weathering and
dissolution of rocks and soils. The United States has established a secondary water
quality standard of 500 mg/l to provide for palatability of drinking water.
Total dissolved solids are differentiated from total suspended solids (TSS), in that
the latter cannot pass through a sieve of 2 micrometers and yet are indefinitely
suspended in solution. The term settleable solids refers to material of any size that
will not remain suspended or dissolved in a holding tank not subject to motion, and
excludes both TDS and TSS.[3] Settleable solids may include larger particulate
matter or insoluble molecules.

6. TDS measurement principle
There are two principal methods of measuring total dissolved solids: gravimetric
and conductivity. The standard method is gravimetric, which is considered the most
accurate and involves evaporating the sample to dryness at 103 °C, then to 180 °C
to remove any occluded water, (water molecules trapped in mineral matrix), then
weighing it with a precision analytical balance (normally capable of 0.0001 gram
accuracy). This method is generally considered best, although it is slow and has
inaccuracies from low-boiling-point chemicals which evaporate with the water.
Electrical conductivity of water is directly related to the concentration of dissolved
ionized solids in the water. Ions from the dissolved solids in water create the ability
for that water to conduct an electric current, which can be measured using a
conventional conductivity meter or TDS meter. When correlated with laboratory
TDS measurements, conductivity provides an approximate value for the
TDS concentration, usually to within ten-percent accuracy.
TSS total suspended solids
total suspended solids (TSS) is the dry-weight of suspended particles, that are not
dissolved, in a sample of water that can be trapped by a filter that is analyzed
using a filtration apparatus. It is a water quality parameter used to assess the
quality of a specimen of any type of water or water body.
TSS measurement principle
Total Suspended Solids (TSS) is one of the method defined analytes. There is no
specific chemical formula for a total suspended solid. Quite simply put, TSS is
anything that is captured by filtering the sample aliquot through a specific pore
size filter. Suspended solids can range from particles of silt or sediment to pieces
of plant material such as leaves or stems. Even insect larvae and eggs can fall in
the general category of TSS. High amounts of TSS can lead to an esthetically
displeasing appearance of a body of water. Either the color or overall turbidity of
the water will be negatively impacted.
A measured volume (no more than 1 L) of sample is passed through a prepared,
pre weighed filter paper. The filter is dried at 104 ± 1°C. After drying the filter is
reweighed and the TSS is calculated.