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Industrial Wastewater nv ronmenta anagement

Dr Muhammad Ali

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Aims and ObjectiveTo introduce Industrial Wastewater

Difference between domestic and IndustrialWastewater

mpor ance o n us r a as ewa er rea menEffects of Industrial Wastewater onstreams/riversTreatment Methods

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Domestic Wastewater ?Domestic sewage is wastewater discharged from sanitaryconveniences in residential, office, commercial, factories andvarious institutional properties.

It is a complex mixture containing primarily water (approximately99%) together with organic and inorganic constituents. Theseconstituents or contaminants comprised suspended, colloidal anddissolved materials. Domestic sewage, since it contains humanwastes, also contains large numbers of micro-organisms and someof these can be pathogenic.

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What is Industrial Wastewater (IWW) ?Industrial (including agro-industrial) wastewaters have very variedcompositions depending on the type of industry and materials

processed. Some of these wastewaters can be organically verystrong, easily biodegradable, largely inorganic, or potentiallyinhibitory. This means TSS, BOD and COD values may be in thetens of thousands mg l −1 .

With very high organic concentrations, industrial wastewaters mayalso be severely nutrients deficient. Unlike sewage, pH values couldbe well beyond the range of 6–9.Wastewaters may also be associated with high concentrations of

dissolved metals.

The flow pattern of industrial wastewater streams can be verydifferent from that of domestic sewage.A significant factor influencing the flow pattern would be the shiftnature of work at factories.

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What is Industrial Wastewater (IWW) ?Industrial wastewaters (including agro industrial wastewaters) areeffluents that result from human activities which are associated with

raw-material processing and manufacturing.

These wastewater streams arise from washing, cooking, cooling,heating, extraction, reaction by-products, separation, conveyance,

.

Water pollution occurs when potential pollutants in these streamsreach certain amounts causing undesired alterations to a receivingwater body.

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What is Industrial Wastewater (IWW) ?Examples of industrial wastewaters include those arising from chemical,pharmaceutical, electrochemical, electronics, petrochemical, and food

processing industries.

Examples of agro-industrial wastewaters include those arising fromindustrial-scale animal husbandry, slaughterhouses, fisheries, and seed oil

rocessin .

Agro-industrial wastewaters can be very strong in terms of pollutantconcentrations and hence can contribute significantly to the overallpollution load imposed on the environment.

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Why is it Necessary to Treat IndustrialWastewater ?

All major terrestrial biota, ecosystems, and humans depend onfreshwater (i.e. water with less than 100 mg L −1 salts) for their

survival.

The earth’s water is primarily saline in nature (about 97%). Of theremaining (3%) water, 87% of it is locked in the polar caps andg aciers. T is wou mean on y 0.4% o a water on eart isaccessible freshwater.

Freshwater is a continually renewable resource, although naturalsupplies are limited by the amounts that move through the naturalwater cycle. Therefore, treatment of wastewater is necessary.

To conserve and protect aquatic life and maintain biodiversity.

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Effects of IWW on the Streams/RiversStream or river can be used for

Drinking purposeSwimmingIndustrial useAgricultural use

All industrial wastes effects the normal life of stream when the effectis sufficient to render the unacceptable for its “best usage”, it is saidto be polluted. The best use means, use of water for drinking,bathing, fishing etc.

Stream can assimilate a certain quantity of waste before reaching apolluted state. A stream is said to be polluted that if it contains anexcessive amount of pollutants.

The following materials can cause pollution:

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Inorganic SaltsInorganic salts are present is most industrial waster, cause water to hardand make stream unfit for industrial, municipal and agricultural usage.Salty water causes scales in water distribution systems, resistance to flowand lowering overall capacity of pipes.Hard water interferes with the dyeing and textile industry, brewing and beerindustry and quality of products in canning industry.

MgSO 4 constituent in hard water causes cathartic effect.Chloride ion increases electrical conductivity.Iron causes stains and spots (e.g paper, textile mills).Carbonates produces scales in cans.Nitrogen and phosphorus causes eutrophication in stream.

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Acids and AlkalisThese discharged by industrial plants makes stream unsuitable notonly for recreational uses, such as swimming and boating but also for

propagation of fish and other aquatic life.

High concentration of H 2SO 4 lower the pH of stream and can causeeye irritation to swimmers, rapid corrosion to ship’s hull and

eteriorate o is ermen s nets.

It is generally agreed that pH of stream must stay between 4.5 and9.5 for survival of fish.

NaOH an alkali which is highly soluble in water and effects thealkalinity and pH of the stream. It appears in water from manyindustrial plants such as soap manufacturing, textile, rubberreclaiming and leather tanning.

Stream containing as little as 12 ppm of NaOH have been reporteddeadly to fish.

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Organic MatterIt depletes the dissolved oxygen of thestreams and creates unpleasant taste,

odours and general septic condition.

Fish and most aquatics die due to lack ofdissolved oxygen.

The critical range of D.O for fish survivalis 3-4 ppm.

Oxygen shortage caused by organicmatter is often considered to be the mostobjectionable single factor in a streampollution.

Phenols effects the taste of domesticwater supply.

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Suspended SolidsThey settled to the bottom sometime orwash-up on the banks and decompose

causing odours and depleting DO in riverwater.

Fish often die because of sudden loweringo DO o stream an so i s t at sett e atthe bottom can cover their spawninggrounds and inhibits propagation.

Visible sludge create poor aesthetic

condition, making the river unsuitable forrecreational purposes.

Increase in turbidity of water and enhance

flooding changes by diminishing the streambed volumes.

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Floating Solids and LiquidsThese includes, Oils, grease and other materialswhich floats on the surface. They make the riverunsighty and obstruct passage of light through

water, thus retarding the growth of vital plantflood (photosynthesis).

Some specific objections to oils in stream are: . -

2. It is toxic to certain species of fish and aquaticlife

3. It creates a fire hazard when present on watersurface in sufficient amount

4. Destroys vegetation along shoreline, whichconsequently causes erosion.

5. Render boiler feed and cooling water un-usable6. Causes trouble in water treatment processes by

imparting taste and odours to water and coatingsand filters with a film.

7. Creates layer on the surface of water8. Lower recreational options e.g. boating potential

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ColourIt is contributed by textile, tanniers, slaughter houses, paper andother industries.

It is indicator of pollution compounds present in waste water,absorbs certain wavelength of the light and reflects the remainder.This causes the colour develo ment of stream.

Photosynthesis

Recreation

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Toxic ChemicalsOrganic and inorganic chemicals of even extremely low concentrationare poisonous to fresh water fish and other micro-organisms. They

have accumulative effects on biological systems such as insecticidesas Toxaphenes & Dichlorobenzene have killed fishes in farm ponds.

Organic compounds (acrylonitrile) produced by the chemical industriesor texti e company as a so prove extreme y toxic to t e is i e.

Chlorides (400 ppm) and hexa-valent chromium (5 ppm) are toxic tofish. Copper (0.1-0.5 ppm) is toxic to microorganisms.

Complex inorganic phosphate such as P 2O5 (0.5 ppm) interfere withnormal coagulation and sedimentation process in water treatmentplant. They increase the coagulant dosage and settling time.

Phenols reacts with residual chlorine in water & causes medicinal

taste.

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Typical Heavy Metals in IWW

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Micro-organismsA few industries such as Tannier and Slaughter house wastescontains bacteria.

Vegetable and fruit canneries may also add bacterialcontamination to stream. These bacterias’ are of two types.

1. Bacteria which assists in biodegradation of organic matter inwas ewa er.

2. Bacteria which are pathogenic not only to other bacteria but alsoto humans.

For example, Anthrax Bacillus, originating from tanniers where hides(skins) from anthrax infected animals have been processed.

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Radioactive MaterialsManufacturer of nuclear fusionable materialsNuclear power plant

The problem of radioactive waste is unique, since the effects ofradioactive material are immediate or delayed and radiation cancause accumulative damaging effects on living cells.

Certain high radioactive isotopes such as Stortium Sr 90 & CaesiumCs 137 continue to release energy over long period of time.

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EFFLUENT DIAGNOSIS FLOW CHART (2)

Site area/layout Discharge Consent Sludge Disposal

Constant flow + organic load Equalisation Yes

No

Information needed toselect a biological solution

Aerobic Treatment

Adjust biochemicalcharacteristics

High BOD Yes No

Anaerobic Treatment

Post-Treatment(if required)

Discharge (sewer, riveror land)

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Treatment of Industrial Wastewater

The different types of contamination of wastewater require a variety ofstrategies to remove the contamination.Solids removalMost solids can be removed using simple sedimentation techniques withthe solids recovered as slurry or sludge. Very fine solids and solids withdensities close to one pose special problems. In such case filtration orultra-filtration may be required. Alternatively, flocculation may be usedusing a um sa ts or t e a ition o po y-e ectro ytes.

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Dissolved Air FloatationSmall particulates

Air StrippingVolatile Organics

Membrane Filtration

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Fawley : 2 DAFs 11 metres long x 3.50 metres wide treatingoil emulsions

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Air Stripping

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Oils and Greases

Many oils can be recovered from open water surfaces byskimming devices. However, hydraulic oils and the majority ofoils that have degraded to any extent will also have a solubleor emulsified component that will require further treatment toeliminate.

sso v ng or emu s y ng o us ng sur ac an s or so ven susually aggravates the problem rather than solving it,producing a very difficult to treat wastewater.

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OrganicsOrganic material of plant or animal origin is usually possible to treatusing extended conventional Wastewater treatment processes.

Whereas, Synthetic organic materials including solvents, paints,pharmaceuticals, pesticides, coking products etc can be very difficultto treat .

Treatment methods are often specific to the material being treated.Methods include distillation, adsorption, vitrification, incineration,chemical immobilisation or landfill disposal.

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Acids and Alkalis

Acids and alkalis can usually be neutralised under controlledconditions. Neutralisation frequently produces a precipitate

that will require treatment as a solid residue that may alsobe toxic. In some cases, gasses may be evolved requiringtreatment for the gas stream. Some other forms oftreatment are usually required following neutralisation.

e.g. Dissolved calcium andmagnesium(hardness) reacts with lime (or

NaOH) and soda ash to precipitatecalcium carbonate and magnesiumhydroxide

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Toxic materials

Toxic materials including many organic materials, metals (such aszinc, silver, cadmium, thallium etc.) acids, alkalis, non-metallic

elements (such as arsenic or selenium) are generally resistant tobiological processes unless very dilute. Metals can often beprecipitated out by changing the pH or by treatment with otherchemicals. Many, however, are resistant to treatment or mitigation

.

Solids Contact Clarifier–Metals Removal

Pipe Mill

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Ion ExchangeWhenever an ion is removed out of an aqueous solution and isreplaced by another ionic species, this is what we generally refer

to as “ion exchange”.Removes a wide range of cations and anions which make up TDSin water.

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Bibliography Wang & Howard. "Handbook of Industrial and Hazardous Wastes Treatment“ USA2004.Activated Sludge Treatment of Industrial Wastewater by Wesley Eckenfelder and JackMusterman. 1998The Industrial Wastewater Handbook by Ralph L. Stephenson and James B.Blackburn Jr. (1997)Heavy Metals Effects on Biological Wastewater Treatment: Toxic Effects of Heavy

Majid Saidi (2011).Industrial Wastewater Treatment: A Guidebook by J.D. Edwards (1995)Industrial Wastewater Treatment by Wun Jern Ng (Nanyang Technological University,Singapore.Southern Watershttp://www.southernwater.co.uk/microsites/WasteServices/Default.asp (accessed

20/11/11).Dissolved Air Flotationhttp://www.wpl.co.uk/?page=IndustrialWastewaterTreatmentPlants