sorting and material recovery (solid waste management)

7/30/2019 SORTING AND MATERIAL RECOVERY (SOLID WASTE MANAGEMENT)

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SORTING AND MATERIAL

RECOVERY

Lecture # 4


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OBJECTIVES OF SORTING

The following are the objectives of sorting in the Pakistan context:

(a) To separately store recyclable material for reuse.

(b) To ensure that waste which can be processed for recovery of material andenergy (through composting, incineration or any other suitable technology)

does not become co-mixed with undesirable elements.

(c) To separately store hazardous material for disposal in hazardous waste

landfills or appropriate processing.(d) To minimize the waste and ensure reduction in landfill space for final

disposal


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STAGES OF SORTING

There are various stages at which sorting can takeplace in the waste stream. These can be identified as

the following:

(a) At the source / household level

(b) At the community bin (municipal bin)

(c) At a transfer station or centralized sorting facility

(d) At waste processing site (pre-sorting and post-

sorting)(e) At the landfill site


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SORTING OPERATIONS

Sorting can be carried out manually or through semi

mechanized and fully mechanized systems.

Manual sorting operations comprise of

(a) unloading the waste

(b) manually (with protective measures) spreading the

waste

(c) hand picking (with protective measures) visually

identifiable waste for reuse

(d) collecting and stockpiling the remaining waste.


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Semi-mechanized sorting operations comprise of

(a) unloading of waste (mechanized)

(b) loading of waste on conveyor belts (mechanized)

(c) hand picking of visually identifiable waste off the belt for

reuse (manual)

(d) collecting, stocking and reloading the remaining waste

(mechanized)


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Fully mechanized sorting operations comprise of

(a) unloading of waste

(b) size reduction of waste through shredders and crushers

(c) size separation of waste using screening devices

(d) density separation (air classification) of waste

(e) magnetic separation of waste

(f) compaction of waste through balers/crushers

(g) reloading of waste


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CURRENT STATUS

Household waste sorting in Pakistan is a complex activity which involves

more than one sector and more than one location. For the sake of

understanding it is convenient to divide it into primary level sorting and

secondary/tertiary level sorting.


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Primary and Secondary/Tertiary

Sorting

Currently sorting of household waste is carried out both at the household

level by the inmates and at the common bin level by rag pickers. This

seems to be the general picture around the country except in few

instances where NGO (Non-Governmental Organization) or municipality

intervention has attempted to introduce household sorting on a moreintensive level.

Primary sorting is carried out both within the household, and at the

municipal bin or at the final disposal site such as the landfill, or

waste dump.

Further or secondary /tertiary sorting is carried out in the recycling trade

chain by kabaris and middlemen.


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Occupational Health

At the municipal bin level, injuries and infection can

be caused to rag pickers. There have been a few

studies done on the occupational health risk to rag

pickers, and injury rates can go up to higher permonth. They have also been found to have infected

wounds, sore feet, but no specific study has been

done which isolates health effects such as an

increased incidence of illness directly attributable towaste, and not other socio-economic factors.


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Hazardous Substance Containers

Large to medium-sized old pesticide cans, used aerosol cans

etc. are sold by households mostly directly to the kabari.

These are either used to reclaim the metal or reused as water

containers etc. Both practices are hazardous, but there is very

little awareness of this.


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Household Batteries and Other Toxic Wastes

There is currently no separate collection mechanism for any other household toxicwaste. Items here would include household batteries, small-sized paint cans,

broken thermometers, household chemicals etc. The collection system does not

exist since there are no plants to recycle these, and also since there are no

producer take-back mechanisms in place.

Infectious Wastes

Household infectious wastes consists of home care items such as bandages,

cotton, needles used for insulin and other purposes, sanitary napkins etc. There is

no segregation of these wastes nor any mechanism for disinfection before disposal.


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NON-RECYCLABLE PACKAGING

Many items are left out from the collection system, since the

informal sector either does not have the technology to process orrecycle them or it is not paying enough for the ragpicker to collectthem. Examples of the first would include new types of multi-layered or multi-material packaging such as tetrapacks, medicinepackaging, squeezable tubes, laminated packaging, plastics like PolyEthylene Terethalate (PET) etc.

The second category, i.e. uneconomic to collect, would include soggy

paper, crushed glass, fluorescent tubes, used batteries, thin plasticcarry bags, which are of minimum or no economic value. Of these

carry bags are worth a special mention since they have become asource of country wide citizens protests. These bags, being verythin, require a large number to be collected before they make upa sellable weight.


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PROBLEMS AND DESIRABLE CHANGEThe main problems of sorting of waste as it is carried out manually at

various stages listed below:

(a) Waste gets scattered at the bins.

(b) The sorting itself entails rummaging through waste by ragpickers exposing

them injuries through cut glass, metals as well as diseases through

household infected waste as well as medical waste in case it has beenmixed.

(c) Some types of waste does not get recycled, since it is not currently

recyclable.

(d) Toxic or hazardous waste does not get collected and ends up either in

landfills or in composting operations. Both cause other contamination suchas of groundwater or of the compost.

(e) Recycling takes place in very poor health and environmentally unsafe

conditions.


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Long Term Desirable Changea)An organized colony-wise collection system involving rag pickers, with

proper gear and protection.(b) Investments in the recycling sector to ensure that the units are safe and

operate at economic scales.

(c) Augmentation of the material recycling trade through implementation of

laws.

(d) Development of recycling laws for specific types of wastes.

(e) Incorporation of producer responsibility for collection and disposal or

recycling of specific types of wastes, especially hazardous wastes.(f) Promotion of simple disinfection techniques and devices such as needle

cutter for infectious waste to be pre-treated before disposal.


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(g)Maintenance of the existing kabari system.(h) Pre-sorting of waste for composting operations, through mechanical

means


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STORAGE OF WASTE AT SOURCE

Storage of waste at source is the first essential step of

Solid Waste Management. Every household, shop

and establishment generates solid waste on day to

day basis. The waste should normally be stored atthe source of waste generation till collected for its

disposal.


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PRESENT SCENARIO

No Storage at Source

Generally no bins for storage of domestic, trade or institutional waste are

kept at source. Very few people keep personal bins for storage of domestic, trade

or institutional waste at source. The percentage of such people is insignificant.

Under the situation most of the domestic waste as well as waste from shops,

offices and establishments including hospitals, nursing homes, hotels, restaurants,

construction and demolition wastes, etc., come on the streets or is disposed of

unauthorized on public or private open plots or even discharged in the drains or

water bodies nearby resulting in clogging of drains, pollution of water resources

and increase in insanitary conditions in the urban areas.


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Storage of Waste, Wherever Practiced, does not Synchronize with

Primary Collection System

System of storage of waste at source, wherever practiced, by and large, doesnot synchronize with the system of primary collection with the result thewaste stored at homes, shops and establishments in domestic, trade orinstitutional bins also finds its way on the street resulting in unhygienicconditions on streets. Some types of receptacles presently used for storageare as under:

Buckets

Plastic bins

Plastic bags

Metal bins with or without lids

By and large such bins used are without lids. These are unsuitable for

storage of food waste for 24 hours and more in the Pakistani conditions as waste

starts stinking very fast due to putrefaction.


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Types of Recyclable and Other Non-Bio-degradable Wastes

to be Kept Separately

Paper and plastic, all kinds

Cardboard and cartons

Containers of all kinds excluding those containing

hazardous materials

Packaging of all kinds

Glass, all kinds Metals, all kinds

Rags, rubber, wood


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MEASURES TO BE TAKEN BY THE LOCAL

BODIES TOWARDS SEGREGATION OF

RECYCLABLE WASTE

?


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sorting and material recovery (solid waste management)

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