document

Cross-border network for knowledge transfer and innovative development in wastewater treatment

WATERFRIENDHUSRB/1203/221/196

1st HUSRB Students Meeting

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1st Students Meeting Waterfriend

Wastewater and certain methods for its analysis

Božo Dalmacija, Jasmina Agbaba, Malcolm Watson

University of Novi Sad Faculty of Sciences, Trg Dositeja Obradovića 3, 21000 Novi Sad

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Wastewater -water which is contaminated

in any way during use.

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Water polluters:

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According to its origin, wastewater can be classed as:

a) municipal wastewater - water used in households, institutions, schools, hospitals, etc.;

b) industrial wastewater - used water from industrial plants;

c) wastewater from livestock facilities (farms) - usually wet manure removed from breeding pigs and so on;

d) atmospheric waste water - rainfall which flows from the city and industrial areas and which can contain various materials found locally; and

e) drainage wastewater from landfills containing municipal and other waste.

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Municipal wastewater• Long term constant composition in a region, as a result of the

standard of living and way of life of the population.

Parameter Unit ValueBOD5 g/PE.day 60COD g/PE.day 120-150Suspended matter g/PE.day 70-90Total phosphor g/PE.day 12-15Total nitrogen g/PE.day 2.5-3

• Pollution amounts and loads may be expressed using norms, i.e. standard values per unit population

• (PE - Population Equivalent)

Table 1. Pollution by PE

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• The amount and composition of municipal wastewater shows typical variations during the day as a result of the rhythm of life of the population.

• Certain variations in flow and composition may also occur during the year.

Figure 1. Usual daily and weekly variation of municipal wastewater

Rural centres - below 150 l / capita per day, Urban areas - 200 l / capita per day.

S M T W T F SFl

ow m

3 /s

rainy period

dry period

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• The smaller the sewage system and the lower the population served by the sewage system, the greater the daily variation, i.e. the greater the ratio between the maximum and medium flows

Figure 2. Daily fluctuations in municipal wastewater: flow: 34500 m3/day; suspended matter: 9620 kg/day; BOD5: 7420

kgO2/day; total nitrogen: 1620 kgN/day 8

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Parameter VariationSettleable fraction(%)

pH 7.5-8.5Dry extract, mg/l 500-1500 10Total suspended solids, mg/l

150-500 50-70

BOD5, mgO2/l 100-400 25-40

COD, mgO2/l 300-1000 25-40TOC, mg/l 100-300Total nitrogen, mgN/l 30-100 8-12NH4-N, mgN/l 20-80 0

NO2-N, mgN/l <1 0

NO3-N, mgN/l <1 0Detergents, mg/l 6 – 13 0Total phosphor, mgP/l 4 –18 10 –20Lipids, mg/l 50 – 120 8 –20

Table 2. Characteristics of municipal wastewater

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Industrial wastewater

Industrial wastewaters often have variable character, both in quantity and in quality.

Wastewaters vary by type of industry, but also frequently between the same type of factory, as a consequence of differences in production techniques, raw materials, hours worked, etc.

Figure 3. Example of an industrial wastewater daily flow

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• Industrial wastewater can be divided into four categories depending on its quality and method of formation:

– technological wastewater– specific wastewater– useful discharge– occasional discharge

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• The quantity and quality of industrial wastewater depends on:

• industrial activity, plant capacity and raw materials used;

• ability to recycle or separate different wastewater streams;

• daily wastewater amounts of each type;

• average and maximum daily amounts (frequency and duration) of water;

• average and maximum flows of pollutants (frequency and duration) for each specific waste discharge.

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Monitoring of wastewater

The selection of monitoring parameters depends on the:• manufacturing process, • raw materials and • chemicals used in the plant/factory.

Wide range of monitoring frequencies according to the needs and depending on the risk posed to the recipient ecosystem, and in accordance with the monitoring approach undertaken.

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• Parameters are therefore grouped according to the activities performed by the polluter and currently applied technology.

• In all these cases, there is a certain number of parameters common to this type of wastewater - "general parameters".

• Large numbers of factories/companies - various pollutants in their wastewater.

• Analytically irrational and economically unjustified to analyse all possible pollutants.

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Parameter ParameterFlow - daily average (m3/day) Fixed and volatile solids ignited at 550 °C(mg/l)

Air temperature (oC) Loss on ignition (mg/l)

Water temperature (oC) Suspended matter (mg/l)

Colour (description or as spectral adsorption coefficient (SAC))

COD (dichromate method), homogenised sample (mg O2/l)

Odour (description)COD (dichromate method), filtered and settled sample (mg O2/l)

Visible material (description) BOD5, homogenised sample (mg O2/l)

Settleable solids (after 2 hours) (ml/l) BOD5 filtered and settled sample (mg O2/l)

pH Total nitrogen (mg N/l)

Dry residue (mg/l) Total phosphorus (mg P/l)

Table 3. General wastewater parameters

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• “Specific parameters“ - parameters that characterize different activities, technological processes, and in some cases differences in production organization.

• These parameters are defined after examining the production process and defined for wastewaters in certain factories or companies.

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Table 4. Examples of specific parameters by industrial activity

Activity Specific parameter analysed in this wastewater

Agriculture

LivestockPig farmsPoultry

- ammonium ion (mgN/l)- organic nitrogen (mgN/l)- total coliform bacteriaFor farms greater than 40000 poultry, 2000 pigs

(larger than 30 kg) or 750 sows, the following should also be determined:

- Cu compounds (mg/l)- Zn compounds (mg/l)

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Food manufacturing

Production, processing and preservation of meat and meat products

- oil and grease (mg/l)- sodium (mg/l)- chlorides (mg/l)- surface active agents, (mg DBS/l)- total coliform bacteria- fecal coliform bacteria

Processing and preservation of fish and fish products

- oil and grease (mg/l)- sodium (mg/l)- chlorides (mg/l)- surface active agents (mg DBS/l)

The production of vegetable and animal oils and fats

- oil and grease (mg/l)- surface active agents (mg DBS/l)- sulphates (mg/l)

Processing and preservation of milk

- oil and grease (mg/l)- surface active agents (mg DBS/l)- m- and p-alkalinity (mVal/l)- m- and p-acidity (mVal/l) 18

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Tanning and leather production

Tanning and dressing of leather, manufacture of luggage, handbags, saddles, harness and footwear

- chrome (mg/l) - if chrome tanning agents are used- aluminium (mg/l) - if white tanning used- calcium (mg/l)- sodium (mg/l)- sulphates (mg/l)- m- and p-alkalinity (mVal/l)- m- and p-acidity (mVal/l)- toxicity (%)

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Manufacture of basic metals and fabricated metal products

Manufacture of fabricated metal products, except machinery and equipment

Depending upon the technology used to protect the metal products, the following need to be determined:

- all metals present in the different reagents such as:preparation, cleaning and activating metal products: Fe, Mn, Zn, Cd, Sn, cyanides, F, Cr, etc.coating metals Cr (all forms), Zn, Ni, Ag, Al, Pb, Ti, B, Sn, etc.post processing: Cr, Zn, Co, etc.-m- and p- alkalinity or acidity (mVal/l)-toxicity (%)

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• Flow measurements– quality of wastewater irrelevant if

quantity not known

• Closed pipe flow– magnetic, ultrsonic: generally require

pipe to be kept full

• Open channel– Primary measuring device – weir/flume– non contacting level measuring device –

radar/ultrasonic– easier maintenance, easier to use

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• Preliminary wastewater testing - quick qualitative or semi-quantitative tests, carried out by spectroscopic, micro - and macro chemical methods.

• Full program of work – based on the preliminary results, a methodolgy must be made for the analyst to follow when analyzing the samples.

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• Preliminary testing - allows the analyst to correctly determine:

– the amount of water required for testing,

– the number of special samples to be taken,

– specific requirements for the taking and storage of individual samples,

– the proper selection of analytical methods, and

– any links between the presence of one component or water property with the absence of an other.

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error

investigation of wastewater

sample

measured value

chemical information

wastewater sample

analytical result

problem

investigation of wastewater

sample

prep. meas. assess.

wastewater sampling strategy

interpretation

wastewater sampling

characterisation

data analysis

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Sampling• Proportional to time. Take the same amount of sample

(q=constant) at the same time interval (t=constant) and the composite sample is defined by a certain time interval.

• Proportional to flow.• Take different amounts of sample proportional to the

wastewater flow (q=kQ) at the same time interval (t=constant);

• Take the same amount of sample (q=constant) at different time intervals depending on the wastewater flow (t=kQ).

Figure 4. Different sampling possibilities

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Sample Sampling methodGrab Sample taken at a certain time and placeComposite A mixture of samples taken to be proportional to the flowSpatial composite

Mixture of samples taken at one general location at various points, e.g. at the aeration basin, the settling tank, etc.

Cumulative Same amount of sample taken at same time intervals.

Tabela 5. Sample definitions

If the wastewater sample is not representative, either at the time of sampling or the time of analysis, even the most careful analysis will not be useful.

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• According to the nature of the components that need to be determined, samples can be classified into two groups:

– samples taken for the determination of characteristics and contents which change in contact with air, and

– samples taken for the determination of properties that do not change in contact with air.

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Water samples for air-sensitive parameters• Require the use of specific sampling methods - to avoid sample

contact with air, sample containers must be immediately sealed or conserved.

• Separate samples must be taken for the determination of air sensitive components, such as: acidity/alkalinity, ammonia and ammonium ions, CO2, Fe2+ and Fe3+, dissolved oxygen, nitrites, residual chlorine, chlorine demand, pH, hardness, phenols, H2S and sulphides, SO2, sulphites and bisulphites.

• It is even necessary to carry out some analyses on the spot, during or immediately after taking the sample (dissolved gases, pH, suspended solids).

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Water samples for air-non sensitive parameters

• Composite sample is usually taken - it is still necessary to take precautions against possible contamination of the sample solids from the air.

• From one composite sample, the following parameters may be determined: organic substances, suspended solids, nitrates, phosphates, calcium and magnesium, sulphates, total iron and other metals.

• Separate samples are taken for the determination of substances extracted by some solvent (grease, suspended matter, detergents).

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• Samples taken for wastewater parameters which do not change in contact with the air may or may not be filtered prior to analysis, depending on the nature and quantity of insoluble material, and the applied method of measurement.

• According to the purpose of the investigation and the components to be determined, analysis might include:

– only the aqueous phase,

– only the solid phase, or

– the entire system.

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• For the analysis of gaseous wastewater components (oxygen, CO2, H2S), prior filtration of the sample is not allowed, in order to prevent the loss of these components.

• If filtration is not allowed, as outlined in the analytical method, the precipitate may be separated by centrifugation, clarification by standing, etc.

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An intelligent and meaningful concept of laboratory analysis includes:

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• Today, there are many known methods for the qualitative detection and quantitative determination of pollutants in wastewater, and they are continuously improving.

• The choice of method depends on the – purpose and goals of the wastewater investigation and the

information desired, – from the concentration of components determined (the maximum

allowable concentrations of pollutants prescribed by regulations are often highly relevant),

– the type of results required (approximate, accurate and correct results),

– the instrument and chemicals that are available, – to possible analytical limitations due to interference and others.

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Methods can be classified according to their purpose:

• Reference (standard) methods• Rapid or screening methods• Routine methods• Automated methods• Modified methods

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Reference (standard) methods:

– Standards of the International Organization for Standardization (ISO),

– Standard Methods for the Examination of Water and Wastewater published by the American Public Health Organization (APHA),

– American Waterworks Association (AWWA) – Water Pollution Control Federation (WPCF), – Environmental Protection Agency (EPA) .

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Rapid or screening methods:

– used for preliminary testing of a large number of samples, as an expedient means of determining whether any sample must be subjected to additional testing with more accurate methods.

Routine methods:

– official or standard, but may be modified to be better suited for application with a large number of similar samples.

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Automated methods:

– using automated equipment, which can also be official or rapid methods.

Modified methods:

– can be are official or standard methods that have been modified in order to simplify them or adapt them to different types of samples from the original planned method, or to remove abnormal interfering substances.

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• Non-standard methods, and those that are published by reputable scientific journals or research companies.

• The choice of optimal method is very important – compliance with the quality assurance program based on

scientific and technical information,

– consideration of practical requirements (time and cost of wastewater analysis, the accuracy and precision of analytical instruments, and the experience and skills of the analyst, etc).

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Simple, quick and inexpensive determination of multiple parameters .39

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• If there is a choice between several good methods, preference is given to: – the method recommended by the relevant international

organizations, – methods validated by interlaboratory tests conducted in

accordance with international protocols, – methods validated in the required concentration range, – methods which are often applied, are simple, fast and economical, – methods applicable to samples similar to those investigated,– methods applicable to different sample types, and materials and – methods which allow for the traceability of each result.

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The most important quality parameters of an analytical method

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• Accuracy is defined as the degree of agreement with the actual measured or expected value.

• Accuracy is measured by comparing the response of the method to the real value, and is expressed as the recovery.

• Analysis of a Certified Reference Material –CRM• Determination of percentage yield - Recovery• Comparison with other methods already confirmed to be

accurate

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• Precision is the degree of mutal agreement between individual measurements made under the same conditions.

• Can be expressed using different statistical indicators:– standard deviation, – relative standard deviation

(RSD).

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precision

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Limit of Detection (LoD) and

Limit of Quantitation (LoQ)

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• Instrument detection limit (IDL) the concentration of analyte that gives a signal five times the signal/noise ratio

• Method detection limit (MDL, LoD) lowest concentration of an analyte which can be measured and reported with 95% confidence that the analyte concentration is greater than zero.

- Criterion of detection CD = t0.95(f) * Sbl * √ (1 + 1/n)- Limit of detection LoD = 2 * CD- t0.95 – from Student’s table - (f) – number of measurements used for Sbl- Sbl - standard deviation of blank- n – number of blanks during routine analysis (2)

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• Practical quantitation limit (PQL, LoQ), the lowest concentration that can be determined reliably – in the laboratory using routine procedures.

LoQ = Xaverage blank + 10 * Sbl

LoQ = Xaverage blank + 5 * LoD

• Xaverage blank – average value of blank or sample with extremely low level of analyte

• Sbl – standard deviation of blank

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• Specific methods allow determination of one analyte, irrespective of the presence of other components

• Selective methods allow for the determination of more than one similar analytes at the same time, irrespective of the presence of other potentially interfering components

• May be necessary to remove or mask such interferences.

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• Method sensitivity characterises a method or instruments ability to differentiate two different concentrations of an analyte at a certain degree of confidence.Sensitivity is expressed by the slope of the calibration curvey = f(x), which expresses the relation between the output signal and analyte concentration.

cAaslope

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• Linearity within the working range of the method, the analytical signal should have a linear dependence on the analyte concentration.

• Linearity determined by drawing a calibration curve

• At least 6 points required• Each point should be replicated at

least twice• Validation of the method should

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• Repeatability is the property of a method describing how close the results of repeated consecutive measurements of the same analyte are, using the same procedure, analyst, instrument, place and within a short time period.

• Reproducibility is the property of a method describing how close the results of repeated measurements of the same analyte are, using a different analyst, different reference standards, and different instruments and laboratories, over a longer period of time.

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• Analytical robustness describes how sensitive a method is to slight changes in conditions such as temperature, pH, reagent concentrations, reaction times, etc.

• The more robust a method, the less like it is to be overly sensitive to small variations in laboratory conditions.

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After validation• Permanent control of experimental conditions to

maintain method performance at an established level

• Internal controls of LoD, accuracy, precision, comparison with results from authorised methods

• Validation must be repeated whenever a method is modified or changed (extension of range, different reagents, additional matrices, etc)

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ANALYTICAL PUZZLE

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Presentation/lecture has been produced with the financial assistance of the European Union. The content of the presentation/lecture is the sole responsibility of University of Novi Sad, Faculty of Technology and can under

no circumstances be regarded as reflecting the position of the European Union and/or the Managing Authority.

Hvala na pažnji!Thank you for your attention!

Köszönöm a figyelmet!

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