ERT 319/3 INDUSTRIAL WASTE TREATMENTSEM 1 (2015/2016)

Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, article 2

WASTE ?

(Nemerow and Agardy, 1998)

"Wastes" are substances or objects which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law.

The goal of effective industrial waste treatment is directed towards the removal of all contaminants that adversely impact the water as well as air and land environments.

History of waste treatment & disposal• Population moved away from disperse geographical

areas to congregate together communities need proper waste handling

• 500 BC ( Athens) - law for banning the throwing of rubbish into the streets, apply open dump

• Industrial revolution 1750-1850 increased industrial & domestic waste legislation was introduced.

(more info on history: refer “Waste Treatment and Disposal, 2nd Edition, Paul T. Williams”)

• In Malaysia; National Environmental Policy (2002), run by Department of Environment Malaysia (DOE)

Covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use.

Most industries produce some wet waste although recent trends in the developed world have been to minimize such production or recycle such waste within the production process.

However, many industries remain dependent on processes that produce wastewaters.

Impurities in ww are mainly due to the presence of solids in the water. The solids may be organic or inorganics in nature and may be present in suspended, colloidal, dissolved or in the various forms of their combinations.

The prescribed limit or acceptable level of concentration of impurities or pollutants is laid down by the local authoroties such as Jabatan Alam Sekitar.

The final discharge of ww will normally be either into the body of water or onto the land. The receiving bodies of water may be streams, lakes, ponds, canals, rivers, seas etc.

Fundamentals of Wastewater

Any water @ liquid that contains impurities or pollutants in the form of solids or gasses or their combinations in such a concentration that is harmful if disposed into the environment

WASTEWATER

CONCEPT OF TREATMENT

The partial reduction @ complete removal of excessive impurities present in wastewater.

WASTEWATER TREATMENT

The excessive impurities imply to the constituent (s) concentration(s) that is more than the acceptable level(s) for final or suitable reuse of treated wastewater.

If the objective is to simply dispose of the final effluent into the body of water (receiving streams) or onto the land, the conc of specific constituents is reduced only up to acceptable limits prescribed by the local authorities

Depends on the intended level of treatment

TYPES OF WASTEWATER

Domestic Wastewat

er

IndustrialWastewat

er

Used water which has been discharged from the residential.

The composition of WW depends on the source of its generation

WW Generated by large & medium scale industries.

Vary ing quantity & quality from

industry to industry and process

to process for the same industry

Contains organics & inorganics

solids & microorganism (bacteria)

Also known as municipal WW.

Contains organics & inorganics

solids & microorganism (bacteria)

Waste treatment & disposal

In general, the first step in minimizing the effects of industrial wastes on receiving streams may be accomplished by:

STEP 1 : VOLUME REDUCTIONIn general, the first step in minimizing the effects of industrial wastes on receiving

streams and treatment plants is to reduce the volume of such wastes. This may be

accomplished by:

Reusing both industrial and municipal effluents as raw water supplies

Changing production to decrease waster

Conserving wastewater

Classifying wastes

If wastes are classified so that manufacturing-process waters are separated from cooling waters, the volume of water requiring intensive treatment may be reduced considerably.

Waste from manufacturing processes:Example: Water discharged from dyeing and washing of textile fabrics.Water used as cooling agents in industrial processes:Example: Cooling waters (CW) have been found to be contaminated by small leaks, corrosion products or the effect of heat. However, CW for power plant may contain hazardous contaminants.

Sometimes it is possible to classify and separate the process waters themselves so that only the most polluted ones are treated and the relatively uncontaminated ones are discharged without treatment.

Classification of Wastes

Water conservation is waste saved.

Example:1)Steel mills reuse CW to quench ingots2)Coal processes reuse water to remove dirt and other noncombustible materials from coal. Concentrated recycled wastewaters are often treated at the end of their period of usefulness, because usually it is impractical and uneconomical to treat the wastewaters as they complete each cycle.

The savings are twofold: Water costs and waste-treatment costs are lower.

Conservation of Wastewater

Changing production to decrease wastes is an effective method of controlling the volume of wastes but is difficult to put into practice.

It is hard to persuade plant managers to change their operations just to eliminate wastes. Normally, the operational phase of engineering is planned by the chemical, mechanical, or industrial engineer whose primary objective is cost savings.

The main considerations of the environmental engineer, on the other hand, include the protection of public health and the conservation

Changing Production to Decrease Wastes

Practiced mainly in areas where water is scarce or expensive, reusing industrial and municipal effluents for raw water supplies is proving a popular and economical method of conservation.

Although there are many problems involved in reusing effluents for raw water supply, it must be remembered that any water supply poses problems to cities and industries. Because the problems of reusing sewage effluents are similar to those of reusing industrial effluents.

Reusing Both Industrial and Municipal Effluents for

Raw Water Supplies

Waste strength reduction is the second major objective for an industrial plant concerned with waste treatment.

Any effort to find means of reducing the total pounds of polluting matter in industrial wastes will be well rewarded by the savings earned by reduced requirements for waste treatment. The strength of wastes may be reduced by few methods such as: (1) process changes(2) equipment modifications(3) segregation of wastes(4) by-product recovery

STEP 2: Contaminant Concentration Reduction

• Example: In Malaysia, – Environmental Quality (Industrial Effluent)

Regulations 2009– Environmental Quality (Clean Air) Regulations

1978– Environmental Quality (Control of pollution from

solid waste transfer and landfill) Regulations 2009– Environmental Quality (Refrigerant Management)

Regulations 1999– etc.FOR MORE INFO, www.doe.gov.my

Legislation

Example: treatment of waste (sludge) through landfilling – comply with Environmental Quality (Control of pollution from solid waste transfer and landfill) Regulations 2009.

Treatment of scheduled waste – comply with Environmental Quality (Scheduled waste treatment and disposal facilities ) Regulations 1989

The economics of waste treatment process

• In some countries (mostly EU) – taxes for landfill and incineration.

• Encourage the development of cleaner, lower waste producing process; go for recycle

• Each treatment process posed different economic effect e.g. landfilling’s operating cost is cheaper than incineration. However, incineration produces heat, power or steam (energy). But it also produce hazardous residue, requires expensive special landfill.

• Need to consider environmental and economics.

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