Waste management can include a series of activities. One should distinguish between traditional and/or existing practice (cf. chapter 2) and activities connected to projects that aim to improve and make waste management more efficient. Good waste management focus on a "cradle to grave" approach. This involves active surveying and monitoring of refuse all the way from generation to disposal. Such systems presuppose adequate legislation and strong organizational and institutional conditions. A brief description of the various activities which waste management generally includes is given below. The scope and practice concerning the various activities will vary between countries, cultures and project categories.

A) From generation to transport of waste

a) Storage

Storage of waste takes place at the spot where the waste is produced. Domestic refuse is normally stored continually in a container or sack until collected. The daily production is usually stored inside until it is carried outside for collection. There can be one unit per household or per several households, or local communal collection points where garbage is emptied in a bin or container. In some developing countries, old oil barrels, concrete tubes and other improvised enclosures may be used for storage, often without any systematized garbage collection taking place.

Industry and business often have their own systems with relatively large storage units. Some factories run large refuse heaps on the factory premises, without any form of regular collection. Containers used as storage units are common for a great many industries and outside large market places.

b) Collection

Collection generally takes place by loading waste from the storage containers on to a vehicle, e.g. hand cart, donkey cart, tractor with trailer, lorry or special garbage truck. The garbage is usually collected and emptied by the crew of the vehicle (the garbage collectors), but in some cases collectors make a sound signal on which household members come and empty their garbage into the vehicle.

Collection requires passable routes, and the choice of technology must be adapted to the existing quality of roads, streets and settlements. A simple cart can often be more useful than a modern garbage truck, and labour-intensive methods more efficient than modern, mechanized ones. The choice of technology should also be considered on the basis of available facilities for maintenance. In some places, tractors ordinarily used for agricultural purposes have proved useful for collection and transport of waste. Moreover, in agricultural areas where tractors are used, there is often a good infrastructure with garages and available spare parts.

Wherever there is a systematic collection, small-scale industries and businesses are usually included. Major manufacturing industries producing large amounts of waste usually run their own systems for collection and transport. Collection of sludge from waste water treatment plants also requires separate collection routines.

c) Waste transfer and transport

If the place of disposal is far away or if very small vehicles are used for collection, it can be appropriate to load the garbage on to a larger transport vehicle. Transport is thereby rationalized in that it takes fewer vehicles and crews. Waste transfer can take place by the collection car emptying the garbage into a container for collection by a larger container car, or by the garbage being loaded directly from the collection vehicle on to the transport vehicle. Light vehicles should be used for shorter distances, e.g. tractor with trailer. Transport takes place between collection, any transfer, and the place of disposal. Also in this case, choice of technology should be based on the passability and quality of roads and other infrastructure (cf. booklet 8: "Transport").

B) Waste disposal

This is a common term for how the waste is handled, whether some of it is recycled, treated in some way or another, or placed in a landfill.

a) Source sorting

The purpose of source sorting is to keep waste components separate from each other at the source, or where the waste arises, so that one or more of them can be reutilized or recycled. Usually, cardboard and paper are sorted, but food scraps, glass, metal, plastics, combustible and compostable matter can also be sorted. Such sorting requires that the waste producers are enabled to store waste components separately, and that special collection and transport systems for the various components exist. In developing countries, source sorting is still uncommon.

b) Central sorting

Central sorting takes place by sorting out valuable components from mixed waste. In some industrialized countries, mechanized sorting plants exist, but these have only been tried out to a small degree in developing countries, at least as far as mixed domestic waste is concerned. Manual sorting, however, is quite common, and large amounts of valuable materials are sorted out for reuse (cf. chapter 2). The ratio between the economic value of materials such as plastics, paper, glass, metals, textiles etc. and hourly payment for labour is generally much higher in developing countries than in industrialized countries, so that manual sorting can be cost efficient.

Attempts have also been made to establish recycling centres that pay for recyclable waste. For these to work, relatively high prices must be paid for pure and sorted materials.

c) Recycling

Source sorting and central sorting of domestic refuse are important links in the recycling of waste components. Industry and various businesses often produce large amounts of relatively homogeneous waste. Such waste can often be used as raw material for other industries and/or be utilized in other ways. For example, waste from fisheries, aquaculture, slaughter-houses etc. can be used as animal feed after e.g. heat treatment, sterilizing and/or grinding; sewage, sludge and agricultural waste can be used for fertilization of aquaculture plants and agriculture; wood waste from forestry and wood industries are useable as fuel; dust and slag from smelting works can be used for road construction; iron and other metals can be recycled from rehabilitation of buildings and plants; and chemical residuals and by-products from one factory can be used as raw material in another. In some industrialized countries, waste exchanges have been established, at which waste for sale and demands for particular waste products can be announced.

d) Production of refuse derived fuel (RDF)

The purpose of producing RDF is to sort out a fraction containing the main part of the highly combustible components that can be found in waste, i.e. cardboard, paper, textiles and wood. These are dried, ground and briquetted. The advantage is that a product is made which is dry and storable, in addition to being compact and thus easily transportable. Such RDF can, if the separation is good, be burnt in various types of incinerators without special gas cleaning measures. In developing countries, this method has only been tried out to a slight degree so far.

e) Composting

Composting is a treatment method geared to a quick microbial decomposition of organic matter in the waste. This takes place by grinding, separation of some of the more heavily decomposable components, controlling of humidity and nutrients (usually by means of sewage sludge) and supply of air (aerobic decomposition). The entire process generally takes 1 year, and the compost product can be utilized in agriculture. In addition, carbon dioxide and water are produced, which escape to the atmosphere. Some machine equipment is commonly used for composting, but there are examples of successful comporting processes which are mainly carried out manually. Waste produced in many developing countries is often ideal for composting, and the method could preferably by practiced on a larger scale in areas where agriculture is important. Sewage sludge can also be applicated directly to fields for agricultural purpose, assumed that the content of heavy metals or other poisoning material is not dangerously high.

f) Anaerobic decomposition

Anaerobic decomposition is basically different from aerobic decomposition (ref. e), even if the the decomposition is done by microorganisms. Air is shut off, and the process usually takes place in a reactor. Since the decomposition is anaerobic (without air), inflammable methane gas is generated in addition to carbon dioxide, which can be utilized for energy purposes. Anaerobic decomposition of waste has not been tried out to any great extent yet, while such treatment of farces on a small scale is a well-known technology in many developing countries. The generated gas is utilizable as energy for cooking in the households.

g) Incineration

Burning of rubbish takes place in special incinerators adapted to this heterogeneous fuel which often has a low calorific value as compared to conventional fuels. Proper incineration requires ample supplies of air, a certain resident time and a sufficient temperature. Some harmful waste gas components are nevertheless generated, and a great deal of dust follows the flue gas. Purification of the waste gas is therefore required. It keeps a temperature of 800°-1000 °C, and it is possible to recycle up to 80 per cent of the energy by heat-exchanging the gas with water. Hot water for distant heating, processing heat for industry or steam for electric generators can then be produced.

h) Deposit in landfill

There will always be a need for a landfill, regardless of the means of disposal chosen. None of the methods commented on above can take care of absolutely all of the waste, and all leave residuals which must be handled in an alternative way. A landfill may be anything from an uncontrolled rubbish heap (a dump) in a hollow to a well prepared area with a sealed bottom, a system for accumulation and handling of water leachate, compaction of the waste with a compactor, daily covering of the refuse, enclosures etc. Many landfills and dumps in developing countries have come into being by chance, without necessary preliminary investigations or land-use planning.

C) Management of hazardous waste

Processing procedures for hazardous waste will vary according to type of refuse, degree of toxicity etc. There should be strict requirements regarding storage, collection, transport, transfer and disposal. Hazardous waste should normally not be treated together with other types of waste, but certain types may be burnt together with other waste. In some countries, hazardous waste is deposited in a landfill together with domestic waste, in reference to a theory that the biological processes taking place in domestic waste also decompose hazardous waste. This has not been documented, and concerns, at best, only some very special matter. Organic hazardous waste can be burnt in specially constructed incinerators, whereas inorganic waste can be detoxified chemically, stabilized and/or encapsulated prior to a controlled depositing. The processing procedure will only be effective and proper if the strictest international requirements and directions are complied with. Special training and protection of those engaged in handling of refuse are necessary. All hazardous waste must be stored in clearly marked barrels, containers etc. The marking must pay attention to any limitations concerning language and reading skills, and clearly caution anyone coming into contact with the waste (cf. chapter 3.6).

a) Storage

Hazardous waste commonly goes through different periods of storage before final disposal or destruction. The waste is often stored as it is being generated, and up to a certain amount before it is transported onwards to an intermediate storage station, or direct to the disposal plants. However short the period of storage, one should take great care to reduce the risk of leakage into the environment. For some types of hazardous waste there is still no safe method of processing or disposal. Such waste must be stored until new technology has been developed, or until decomposition over time has removed the risk of serious pollution. Storage facilities for such waste should be constructed in accordance with strict international directions and in stable localities.

Measures concerning waste processing should pay attention to the special conditions existing in the various developing countries. Transfer of technology is often an important element in development aid, and a well adapted choice of technology should be based on a consideration of various conditions, both locally and nationally. In order to achieve sustainable measures, it is often necessary to carry out investigations and research to form a basis for the planning of measures, and choice of technology and localization, accomplishable within the economic, technological, institutional, cultural and environmental framework conditions and opportunities in an individual country and in a particular locality. With regard to choice of technology, except for the handling of hazardous waste (cf. chapter 3.6), these conditions can lead to decisions which will not always meet standards that are common in technologically highly developed countries. However, experience from developing countries has shown that relatively simple measures can bring considerable, and environmentally sound, improvements.