Solid wastes are unwanted or discarded materials. They may contain dust, ash, paper, packing’s and also profitable matters such as fruits and vegetables. They may be the products from houses or from industrial, commercial and agricultural operations. They are called as litter in country side and refuse in cities.
Health hazard of solid wastes
1. They attract flies and rats.
They may pollute water if rain-water seeps through them
3. They may pollute air by spontaneous or accidental combustion.
Collection of refuse
Refuse is solid waste from cities. It may be collected from market (market refuse), streets (street refuse) industries (industrial refuse) and houses (domestic refuse). In the house, refuse may be stored in steel dust bins or in paper sacks. In the streets, they are dumped in public bins. The bins are kept on a concrete platform raised 2 to 3 inches above ground level. This prevents flood water entering the bins. The refuse is collected from houses and from public bins in carts or vans.
Disposal of refuse
It may be disposed by the following methods:
The refuse is dumped in low lying areas. Due to bacterial action, it is reduced in volume and converted into humus. Disadvantages of dumping are: a. It is exposed to flies and rodents, b. It emits foul smell, c. It may lead to water pollution. 4. It is dispersed by wind.
2. Incineration (or burning):
It is not an useful method except for the disposal of hospital refuse. It is not an advantageous method since a) dust and ash must be separated before incineration b) it is expensive c) it deprives of manure required for the community.
In this method, alternate layers of refuse and night soil are heaped in trenches. The heap is then covered with earth. Heat (over 60°C) is generated by bacterial action which kills pathogenic organisms. Also organic matter is broken down by bacterial action. The end product is called as compost which can be used a manure.
It is useful for small camps. Each day, the refuse is dumped in stench and covered with 20 to 30 cm of earth. After one trench is full, another trench is filled the same way. The contents of the trench may be taken out after 4 to 6 months and they can be used as a manure.