Management of Solid Waste

For waste management we stress on ‘three R’s’-Reduce, reuse and recycle before destruction and safe storage of wastes.

(i) Reduction in use of raw materials:Reduction in use of raw materials:Reduction in use of raw materials:Reduction in use of raw materials:Reduction in use of raw materials: Reduction in the use of raw materials correspondingly decreases the production of waste. Reduced demand for any metallic product decreases its mining, hence less production of waste.

(ii) Reuse of waste materials:Reuse of waste materials:Reuse of waste materials:Reuse of waste materials:Reuse of waste materials: The refillable containers, and plastic bags which are discarded after use should be reused. In Villages casseroles and silos are made from waste paper and rubber rings from discarded cycle tubes. Such practices reduce waste generation.

(iii) Recycling of materials: Recycling of materials: Recycling of materials: Recycling of materials: Recycling of materials: Recycling is the reprocessing of discarded materials into new useful products.

Formation of some old type products e.g., old aluminium cans and glass bottles are melted and recast into new cans and bottles.

Formation of new products: Preparation of cellulose insulation from paper, preparation of fuel pellets from kitchen waste. Preparation of automobiles and construction materials from steel cans.

The process of reducing, reusing and recycling saves money, energy, raw materials, land space and also reduces pollution. Recycling of paper will reduce cutting of trees for making fresh paper. Reuse of metals will reduce mining and melting of ores for recovery of metals from ores and prevent pollution.

(iv) WWWWWaste disposal:aste disposal:aste disposal:aste disposal:aste disposal:

For discarding wastes the following disposal methods can be adopted:

l Sanitary landfillSanitary landfillSanitary landfillSanitary landfillSanitary landfill: In a sanitary landfill, garbage is spread out in thin layers, compacted

and covered with clay or plastic foam.

In the modern landfills the bottom is covered with an impermeable liner, usually several layers of clay, thick plastic and sand. The liner protects the ground water from being contaminated due to percolation of leachate. Leachate from bottom is pumped and sent for treatment. When landfill is full it is covered with clay, sand, gravel and top soil to prevent seepage of water. Several wells are drilled near the landfill site to monitor if any leakage is contaminating ground water. Methane produced by anaerobic decomposition is collected and burnt to produce electricity or heat.

l CompostingCompostingCompostingCompostingComposting: Due to shortage of space for landfill in bigger cities, the biodegradable

yard waste (kept separate from the municipal waste) is allowed to degrade or decompose in an oxygen rich medium. A good quality nutrient rich and environmental friendly manure is formed which improves the soil conditions and fertility. Vermi- technology, using earthworms can further help in converting solid organic waste into good quality compost.

l IncinerationIncinerationIncinerationIncinerationIncineration: Solid wastes can be brunt in large amounts at high temperature (around

1800°C) in incinerator. Incinerator is a high temperature furnace used for burning solid wastes. Earlier incinerators used to be made of simple brick lining, but the modern ones are rotary. Kiln incinerators having a long inclined passage through which the waste is constantly moved. There is about 75% reduction in waste mass and 90% reduction in volume. The incinerators in which the waste to be burnt is not segregated are known as mass burn incineratorsmass burn incineratorsmass burn incineratorsmass burn incinerators. There are special incinerators wheremass burn incinerators potentially harmful or hazardous wastes are destroyed. These are known as HazardousHazardousHazardousHazardousHazardous waste Incinerators.

waste Incinerators. waste Incinerators. waste Incinerators. waste Incinerators.

Incinerators help in substantially reducing the quantity of wastes prior to their final disposal along with electricity generation. It also helps in safely destroying hospital wastes. However, during incineration high levels of dioxins, furans, lead and cadmium may be emitted with the fly ash of incinerator. For incineration of materials, it is better to remove batteries containing heavy metals and plastic containing chlorine before burning the material. Prior removal of plastics will reduce emissions of dioxins and polychlorinated biphenyls (PCBs).

10.10

ELECTRONIC WASTE (E-WASTE) AND ITS DISPOSAL

Electronic waste or E-waste is a new type of waste that has emerged in the recent years due to fast developments in the field of electronics, which keeps on changing the configuration and technology and as a result of that older models of electronic devices become obsolete in a short span of time. E-waste consists of obsolete telecommunication devices, reprograhic devices, security devices, automobile devices besides refrigerators, air conditioners, microwaves and a myriad of other electrical and electronic gadgets which add to the waste stream.

In India, the electronic waste management assumes greater significance not only due to the generation of our own waste but also dumping of e-waste, particularly computer waste from the developed countries. Manufactures and assemblers are estimated to produce around 1200 tons of electronic scrap annually. India being a developing country needs to adopt low cost technology with maximum resource recovery in an environment friendly manner.

IT industry has emerged as the fastest growing segment of Indian industry and its growth rate is almost double the growth rate of IT industries in many of the developed countries. In the IT action plan, the government has targeted to increase the present level, from 5 per 500 people to 1 for 50 people, by 2008.

Out of the nearly five million PCs presently in India, about 1.38 million are either of the old configuration (486) or even below. So a vast amount of equipment is soon going to be added to the waste stream, because upgradation beyond a point would not be feasible. Besides this, huge import of junk computers from other countries in the form of donations or gifts or low cost reusable PCs are going to create a big solid waste management problem in India. PC scrap in the form of monitors, printers, keyboards, CPUs, floppies, CDs, typewriters, PVC wires have already started piling up that are going to increase enormously in the coming years.

E-waste, which on the face of it seems quite clean and safe is not so. Its qualitative characterisation shows it to be very complex consisting of several hazardous constituents that can play havoc with our health. These toxic and hazardous substances are as follows:

(i) Lead and cadmium in circuit boards.

(ii) Lead oxide and cadmium in monitor cathode ray tubes (CRTs). (iii) Mercury in switches and flat screen monitors.

(iv) Cadmium in computer batteries.

(v) Polychlorinated biphenyls (PCBs) in older capacitors and transformers. (vi) And brominated flame retardants on printed circuit boards.

(vii) Plastic casings, cables and polyvinyl chloride (PVC) cable insulation that release highly toxic dioxins and furans when burned to recover copper from the wires. After separating all remaining components, motherboards are put for open pit burning to extract the thin layer of copper foils laminated in the circuit board.

Disposal and recycling of E-waste: Disposal and recycling of E-waste: Disposal and recycling of E-waste: Disposal and recycling of E-waste:

Disposal and recycling of E-waste: It has serious legal and environmental implications due to the toxic nature of the waste. These materials are complex and difficult to recycle in a safe manner even in developed countries. The recycling of computer waste requires sophisticated technology and processes, which are not only very expensive, but also needs specific skills and training for operation.

Unlike many other countries there are no specific governmental legislations on e-waste, standards for disposal and proper procedures outlined for handling these toxic hi-tech products. Consequently, the electronic wastes in our country mostly end up in landfills or are partly recycled in most unhygienic conditions and partly thrown into waste streams.

In India, most of the recyclers currently engaged in recycling activities are poor people, mostly women and children, ignorant about the hazardous materials they are handling and have no access to the expensive technology to handle the waste.

Computer scrap in our country is managed through product reuse, conventional disposal in landfills, incineration and recycling. However, the disposal and recycling of computer waste in our country are still not safe and pose grave environmental and health hazards.

The management of electronic waste has to be assessed in the broad framework of Extended

Producer Responsibility and the Precautionary Principle, so that in future policies the producers

should own the responsibility of dealing with the waste management by taking back such wastes and recycle or reuse them in a safe manner. At present, management options for e-waste are extremely polluting and hence a cause of grave concern.

CHAPTER

XI