Solids Colour Turbidity Conductivity

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Solids, Colour, Turbidity

& Conductivity

Presented by:

M S Bhatti

Guru Nanak Dev University, Amritsar

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Physical characteristics:

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Solids: floating, settable, colloidal, dissolved

Odour

Temperature Density or specific gravity

Colour

Turbidity


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How they are relatedHow they are related

y TDS with conductivity

y Suspended solids with turbidity in settledsecondary effluent.

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Solids Total solids at 103 to 105 C

Total dissolved solids at 180 C for clean water

Volatile solid analysis at 550 C to measure the

biological activity (MLSS & MLVSS) in municipal

sludge.

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1. Total Solids dried at 103 to 105 degree C

2. Total dissolved solids dried at 180 C

3. Total Suspended Solids at 103-105 C

4. Fixed & Volatile Solids Ignited at 550 C

5. Settleable solids for semisolids & sludge

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Significance of Solids

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Water with high dissolved solids are of inferior quality A limit of 500 mg/l is desirable in drinking water

Highly mineralized water is also unsuitable for many industrialapplications

Water with high suspended solids may be aesthetically

unsatisfactory (for bathing!) Solids analysis is important

in the control of biological and physical wastewater treatmentprocesses

for assessing compliance with regulatory requirements

Fixed and volatile solids are used to represent active biomassin the mixed liquor in activated sludge process Volatile and fixed solids do not precisely distinguish organic and

inorganic matter many mineral salts also volatilize


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Solidsy Total solids (TS): Material residue left behind after evaporationof a sample and its subsequent drying in a oven at a definedtemperature to constant weight

y Total suspended solids (TDS): Portion of the material residue of

a sample retained by a filter

y Total dissolved solids (TDS): Portion of the material residue of asample that passes through a filter

y Fixed solids: Residue of TS or TSS or TDS left after ignition for aspecified time at a specified temperature

y Volatile solids: weight loss on ignition

y Settleable solids: Material settling out of suspension within adefined period

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Temperature and duration of drying

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Temperature at which the residue is dried and duration ofdrying are very important - influences

Weight loss due to volatilization of organic matter

Weight loss from loss of mechanically occluded water andwater of crystallization

Weight loss from loss of gases (heating convertsbicarbonates into carbonates and release CO2, anddecomposes carbonate to release CO2)

Weight loss from chemical decomposition and weight gainfrom oxidation

Usually duration of drying is adjusted to obtain constantweight of the residue


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Temperatureand duration of drying

Drying temperatures in practice

103-105rC

1802rC

For estimating fixed solids the residue is

usually ignited at 55050rC to constant

weight in a muffle furnace

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Sample handling, preservation and preparation

If acceptable, avoid large floating particles or submergedagglomerates of non-homogenous materials while sampling

Resistant glass or plastic bottles, provided the material insuspension of the sample does not adhere to walls, are used forholding the samples

Analysis of samples is started as soon as possible (impractical topreserve sample)

To minimize microbiological decomposition refrigerate sample at 4 C

Before taking sample disperse floating oil and grease with a blender

Choose sample size/volume to give 2.5 to 200 mg of residue

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Sample handling, preservation and preparation

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Evaporation dishes of 100 mL capacity of one ofthe following material are used:

Porcelain (9 cm dia.)

Platinum

High silica glass


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Sample handling & preparation

Preparation of the evaporation dish

Heat clean dish to 103-105C/1802C/55050C for 1 hourdepending on the temperature of drying and on the need forignition of the residue

Storing the heated dish in desiccator until needed

Weighing the dish immediately before use for initial weight -balance capable of weighing to 0.1 mg is required

Transfer measured volume of well mixed sample into pre-weighed dish

and evaporate to dryness on a steam bath or drying oven For evaporation in a oven, use temperature 2C below boiling

point to prevent splattering

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Sample evaporation, and drying to constantweight and ignition of residue

Once evaporated to dryness, dry the sample at least for 1hour in a oven at 103-105C or 1802C as required andcool the dish in a desiccator to balance temperature and

weight

Use repeat cycles of drying, cooling in desiccator andweighing until constant weight.

Weight loss


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Fixed & Volatile Solids ignited at 550 C

Ignite the dried residue of the dish to constant weight in a

muffle furnace at 55050C

Raise the furnace temperature to desired level prior toinserting the sample and ignite for 15-20 minutes

Air cool the dish partially and then transfer into

desiccator for final cooling in dry atmosphere, then

weight the dish

Use repeat cycles of drying, cooling in desiccator and

weighing until constant weight is obtained

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Total solids

Well mixed sample is evaporated in a weighed dish and dried toconstant weight in a oven at 103-105rC

Increase in weight of dish represents total solids

)(

1000)/(

mLvolumeSample

BALmgsolidsTotal

v

!B is weight of empty dish

A is weight of dish with residue

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Total dissolved solids

Filter well mixed sample through a fiber filter and evaporate filtrate in

weighed dish and dry to constant weight at 1802rC Filtrate from TSS determination can also be used

Increase in dish weight represents TDS

Highly mineralized samples may require prolonged drying, properdesiccation and rapid weighing

Significant concentrations of calcium, magnesium, chloride and/orsulfate can be hygroscopic and cause problem

Samples high in bicarbonate may require careful and prolongeddrying to ensure complete conversion to carbonate

Glass fiber filter disks, filtration apparatus with membrane filterfunnel or Gooch crucible, and suction flask may be needed

)(

1000)/(

mLvolumeSample

BALmgTDS

v



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Total suspended solids

Filter well mixed sample through a weighed standard glass fiberfilter and dry the residue retained on the filter to constant weight at103-105rC

In case of filter clogging and prolonged duration of filtration take

difference of TS and TDS as TSS

Increase in dish weight is represented by

In case of samples with high dissolved solids, thoroughly wash thefilter to ensure removal of dissolved material

Clogging and prolonged filtration can produce high results dueexcessive solids capture

)(

1000)/(

mLvolumeSampleLmgSS

v



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Fixed and volatile solids

Dried residue left in the dish during TS, TDS and TSS is ignited toconstant weight at 55050rC in a muffle furnace

Solids left after ignition represent fixed solids (total fixed solids

from TS, total dissolved fixed solids from TDS and total suspendedfixed solids from TSS)

Fixed solids can be calculated by

)(

1000)/(

mLvolumeSample

CLmgsolidsFixed

v

!

B is weight of dish after ignition

C is weight of the empty dish

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Fixed and volatile solids

Weight lost on ignition represent volatile solids (totalvolatile solids from TS, total dissolved volatile solids fromTDS and total suspended volatile solids from TSS)

)(

1000)/(

mLvolumeSample

BALmgsolidsVolatile

v

!

B is weight of dish after ignition

A is weight of dish after drying

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Settleable solidsDetermined & reported on either volume (mL/L) or weight (mg/L)

basis

Measurement on volume basis requires an Imhoff cone

Fill Imhoff coneto 1-L mark with sampleand settle for 45 min.

Gently stir sides ofthe cone witharod by spinningand settle for

another 15 minutes Record volume ofthe settled solids inthe Imhoff cone

Measurement on weight basis (indirectmethod)

Determine total suspended solids of well mixed sample

Pour >1-L of sample into a glass vessel of >9 cm dia. to depth >20cm

Let it stand quiescent for one hour

Without disturbing settled or floating material siphon out 250 ml fromvessel center and determine its TSS as non-Settleable TSS

Settleable solids = TSS non-Settleable TSS

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Sludge volume index (SVI)

)/(

1000)/(

Lmgionconcentratsolidssuspended

LmLvolumesludgesettledS I

v

!

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Volume in mL occupied by 1 g of a suspension after 30 min. settling

Applications:

1. Used to monitor settling characteristics of activated sludge and otherbiological suspensions

2. Determined for the mixed liquor of the aeration tank of the ASP

3. Determine SS concentration of a well mixed sample of suspension

4. Determine the 30 min. settled sludge volume


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Applications of solids data in

Environmental Engineering:

Suitability of potential supplies

Need for water softening Corrosion control through pH adjustment

which depends on solids

Design of Primary sedimentation tank

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measures the light transmittingproperties of water

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Turbidity


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Turbidity

Water quality standard: < 5 NTU

Indicates clarity of water

Optical property due to the presence of colloidal matterlike

Clay, silt, finely divided organic and inorganic matter, planktonand other microscopic organisms etc.

Causes light to be scattered and absorbed

Clarity of water is important for Producing products destined for human consumption

Potability Water bodies condition and productivity

Coagulation, settling and filtration are needed for theremoval of turbidity and clarity of water

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Significance of Turbidity

Aesthetic

Filterability: Slow and rapid sand filter

Hindrance in Disinfection

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Principle of Nephlometric Turbidity:

For measurement intensity of light scattered in one

particular direction (at right angles to the light path)

by the sample under defined conditions is compared

with that by a standard reference suspension under

the same conditions

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Turbidity measurement

Should be measured on the same day of sampling If unavoidable sample can be stored in dark up to 24 hours

Storage for longer periods can cause irreversible changes inturbidity

Sample free of debris and rapidly settling coarse sediments,after vigorous shaking, should be transferred into sampletube

Dirty glassware, presence of air bubbles and vibrations canaffect the results

Water colour due to dissolved substances that absorbcolour can lower the turbidity measurement ??

Higher the intensity of the scattered light higher is theturbidity

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Standard unit of turbidity:

Initially 1 mg SiO2/l = 1 unit of turbidity

Now Formazin polymer suspension is used

Preparation of standard stock suspension Dissolve 1.000 g of hydrazine sulfate, (NH2)2.H2SO4 (carcinogenic), in

turbidity free water and dilute to 100 ml

Dissolve 10.000 g hexamethylene tetramine, (CH4)6NH4, in turbidityfree water and dilute to 100 ml

Mix 5 ml of hydrazine sulfate solution and 5 ml of hexamethylenetetramine solution in a 100 ml volumetric flask and allow it to standfor 24 hours at 253rC

Dilute the mixer with turbidity free water to 100 ml to obtainstandard stock suspension of 400 NTU turbidity

Can stand for one month

Can be used for daily preparation of standard reference suspensions ofother turbidities (dilute with turbidity free water)

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Calibration of the turbidity meter:

Follow manufacturers instructions

Run at least one standard reference suspension in each of the ranges


When turbidity expected is 40 NTU dilute the sample to get 30-40

NTU range of turbidity and then measure

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C

CN U

)( v!

A is NTU measured of diluted sample

B is volume of the diluted sample

C is volume of the sample diluted


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Application of turbidity data:

Solids Colour Turbidity Conductivity

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