Knowledge of the sources and types of solid wastes, along with data in the composition and rates of generation, is basic to the design and operation of the functional elements of solid waste management.

Figure 1. Simplified diagram showing the interrelationships of the

Functional elements in solid waste management system

a.    Sources and types of Solid Wastes

The Solid Wastes of a City of Municipality comes from a variety of sources and maybe composed of:

1.    Household garbage and rubbish which are the wastes as a result of house-hold activities such as food preparations, cleaning, sweeping, and gardening, etc.

2.    Commercial Refuse which are wastes arising from commerce such as store, office, hotel, warehouse, or services station wastes.

3.    Institutional Refuse includes wastes from schools and universities, hospitals, government buildings, religious building or military barracks.

4.    Industrial wastes comes from both processing and non-processing industries as well as from utilities. Among such wastes includes packaging materials, food wastes, rejected metals, plastic and textiles, fuel burning residual and spent processing chemicals.

5.    Street sweepings which includes dirt and litter and considering the practice of many people to dump their wastes in the streets, this may also include practically all other kind of wastes.

6.    Construction and Demolitions debris which includes wood, masonry and other discarded construction materials.

7.    Sanitation residues which includes night soil and sludge from sewage treatment plants

b.    Composition and Rate Generation

The general trend is that as the income of the people rises, the per capita waste generation (in weight per person per day) increases; the densities, decreases, the moisture content decreases. The more effluent society uses more and more packaging materials such as paper, glass, and ceramics, metals and plastics. While the waste from the lower income group consists mainly of vegetable and putrescrible matter.

STORAGE

      Proper storage of wastes before they are collected result in higher efficiencies of collection and results to more hygienic surroundings. Storage could be after separate unit (i.e. household) or communal. Piles on the street result when both type storage are inadequate and the street itself became the storage.

c.     Collection

There are four principal mode of collection:

1.    Communal collection – this system is applied when communal containers are used. Containers must be set-up at intervals not exceeding 150 m otherwise people may not be applicable for high class residential areas. But this systems in that the truck could come at any time for collection.

2.    Block collection – this system consists of routes of prescribed intervals. They stop at the middle of each block and gives a signal announcing their arrival so that householders could bring their arrival so that householders could bring their waste bins to be emptied to the truck. This type of collection is suitable only in areas where the signal, perhaps a bell or a horn, can easily be heard and where members of the households are at home when the collection vehicle comes around.

3.    Entrance or curbside collection – this system consists of collection of the waste from bins placed outside the house, either close to the sidewalk at the house entrance prior to collection. Because of problems of bins getting lost, the households will have the collector than block collection.

4.    Door to door – this system consists of collection directly from each household. The residents put their waste bin outside the front door at a fixed time or bring it out on request, and the collector empties the waste into a basket that he carries with him. Naturally, this type of collection can only be carried out during day time, and on a one-shift basis. Difficulty in entering premises such as the presence of dogs is a disadvantage. Also, because of security reasons, most people would not want this kind of collection. And on the part of the collector, it is too laborious.

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