Environmental Management: Principles and practice
Recycling and re-use of pollution and waste
Download 6.45 Mb. Pdf ko'rish
|
5 2020 03 04!03 12 11 PM
Recycling and re-use of pollution and waste
Waste recovery and waste recycling are terms that can lead to misunderstandings: a country might recover 80 per cent of its waste paper but recycle little, instead using CHAPTER ELEVEN 232 it for district heating; another may recover 10 per cent but recycle/reuse most of it. There is usually a need to sort, transport and treat recovered waste. Sorting can be done by the state, companies, householders, individual ‘scavengers’, the waste producers. In the USA ‘reverse vending’ has been tried—a waste-skip credits a company for return of cans, bottles, etc. Plastics and non-ferrous metals are at present difficult to recover: estimates suggested about 5 per cent of Japanese, 15 per cent of European and 10 per cent of USA plastics were recycled in the late 1990s. Even if plastics or metals of the same general type can be recognized, pieces vary in subtle ways and may be attached to other materials or have an unwanted coating or contamination that is difficult to remove. Some plastics absorb chemicals, reducing their value for recycling. Crude sorting is sufficient if the aim is just to recover a limited range of materials like aluminium, glass, low-grade plastics, iron and combustible material for fuel. Developed countries can learn about refuse recycling and reuse from the informal sector of developing countries (Bouverie, 1991). Alternatively, they might export waste (mixtures of plastics packaging) to where cheap labour can sort it. Unless recovery ensures that there are few contaminants, plastics have a low value, making it difficult to pay for collection, sorting, washing, etc. Plastics, and some metals, are difficult to sort into various types, and a less than pure mixture may prevent recycling. Recovered material is often bulky for a given weight, making transport and storage costly (Engstrom, 1992; Fairlie, 1992). Recycling may not be as environmentally desirable as it first seems. Virtanen and Nilsson (1993) suggested that waste paper processing may generate more pollution than burning it for electricity generation and district heating (Kurth, 1992; Pearce, 1998). Controlling packaging materials and ensuring they are labelled should reduce the cost of recycling (Johnson, 1990; Gourlay, 1992:185). Glass can be recycled indefinitely and each time saves on energy compared with production of new material (but, at the time of writing Europe recycled only about 49 per cent of its glass, and some individual countries far less). Reuse, of soft-drinks-or milk-bottles, requires a decentralized network of manufacture. Centralized supermarket retailing in the UK, USA and Europe is unlikely to encourage a return to reusable bottles which are heavier, and so cost more to transport than plastic. Reusable bottles also get damaged and many are not returned, which reduces the value of recycling (North, 1995). If a manufacturing firm arranges to recycle its products, it might be able to restrict sales of salvaged second-hand parts, and so profit. Steel and aluminium can recovery can be worthwhile: the latter saves ca. 95 per cent of the electricity used in making fresh aluminium. Paper can be recycled up to four times before the fibres are damaged too much (The Times, 14 June 1993:33). The increasing use of disposable nappies (diapers), which may also pose health hazards for those working in refuse disposal, might be countered by establishing laundry delivery and collection services—but for this to work consumers need to be assured of very high, standards of hygiene. Organic matter such as human sewage, livestock manure, food waste, straw, paper packaging could be disposed of by fermentation or composting (possibly aided by earthworms). There has been some development of these strategies in China and POLLUTION AND WASTE MANAGEMENT 233 India, linked to biogas production. But of the developed countries it has mainly been Denmark and The Netherlands which have developed these facilities. The viability of biogas production largely depends on the quality of refuse or other waste, and it may be necessary to legislate or subsidize to support composting or fermentation. There are also problems with biogas production and refuse incineration for heat or power in ensuring reasonably consistent energy output. Download 6.45 Mb. Do'stlaringiz bilan baham: |
Ma'lumotlar bazasi mualliflik huquqi bilan himoyalangan ©fayllar.org 2024
ma'muriyatiga murojaat qiling
ma'muriyatiga murojaat qiling