Urban Solid Waste Management

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What is the issue?

Rising incomes and changing lifestyles are generating more and a different kind of waste, but we need to set up systems to deal with this huge pileup.

What was happening before 1970s? Georgia

In the past, in rural areas, food discards were returned to the soil.
Food leftovers were fed to animals and the cattle-shed wastes were thrown in a pit to decompose .
This returned both NPK (nitrogen, phosphorus, potassium) nutrients as well as micronutrients to the soil.
In Portuguese Goa, bullock carts would move from bungalow to bungalow, collecting kitchen leftovers for on-farm composting.
This was the earliest Indian version of doorstep waste collection.
These age-old practices have kept Indian soils rich in carbon, up to 4%.

What is happening now?
Everything changed with the beginning of the plastic era in the 1970s.
When farmers took mixed waste of plastic and degradable items, to their farms, the fields started wearing a non-biodegradable plastic film.
It prevented rain from entering the soil and kept seeds from germinating through them (an example of negative urban-rural connectivity).
This assorted mixed waste presented a major management challenge for the municipal authorities.
City managers forced to deal with this and they began collecting and dumping the waste outside the city limits
.
What are the ill-effects?

• Heaps of waste without exposure to oxygen emit methane which is 21 times more potent as a heat trapping gas than carbon dioxide.
• It also generated ammonia and hydrogen sulphide.
• These heaps also started to produce leachate, a black liquid oozing out from the waste.
• It usually take 25-30 years to slowly decompose,
• continuously releasing methane and leachate.
• The leachate seeped down into the soil and contaminated open wells and even polluted bore wells through natural water channels.
• There is no way to treat this deep underground contamination.
• It made the wells and bore wells unfit for drinking and even for irrigation for decades.

What could be done?

• Households need to be made to stop mixing biodegradable waste with dry waste and keep hazardous domestic waste completely separate.
• The segregation of waste at source into ‘wet’, ‘dry’ and ‘sanitary’ categories is now compulsory for all citizens of India in the Solid Waste Management Rules 2016
• (SWM Rules).
• Tirunelveli in Tamil Nadu is the latest of over 20 urban local bodies to achieve near zero waste to landfill.
• The correct way to manage fresh waste is to expose as much of it to air as soon as possible via windrows .
• Windrows are parallel heaps of waste, not more than two metres high, which are designed to achieve the best conditions for aerating the waste.
• Weekly turning of the waste ensures that all parts of the waste are fully decomposed.
• The process can be speeded up by the addition of
• composting bio-cultures (ex.fresh cow dung).
• This bio-stabilising of biodegradable waste would make a city fully compliant with the SWM Rules 2016.

Source: The Indian Express

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