Health Hygiene & Sanitation

Lesson 30 and 31 : Waste Disposal

Methods Of Excreta Disposal

A classification and description of the various methods of excreta disposal is given below:

1. Unsewered areas
• Service type latrines (conservancy system): Night soil is collected from pail or bucket type of latrines by human agency and later transported in "night soil carts" to the place of final disposal, where it is disposed of by (i) composting or (ii) burial in shallow trenches. The latrines are called service latrines. The night soil in service latrines is a source of filth and insanitation.



Disadvantages:

• perpetuate the disease
• exposed to flies
• possibility of water and soil pollution
• buckets and pans are subject to corrosion and require frequent replacement
• emptying of buckets is not always satisfactory
• employing adequate staff needed for the collection is not consistent with human dignity and is no longer pardonable
• entire system collapses with dire consequences to public health if personnel go on strike.


2. Non-service type of Latrines (sanitary latrines): A sanitary latrine is one which fulfils the following criteria: Excreta should not


1. contaminate the ground or surface water
2. pollute the soil
3. be accessible to flies, rodents, animals (pigs, dogs, cattle, etc) and other vehicles of transmission
4. create a nuisance due to odour or unsightly appearance.



A brief description of some of the well-known types of sanitary latrines is given below:

Bore hole latrine: The latrine consists of a circular hole 30 to 40 cm in diameter, dug vertically into the ground to a depth of 20 ft. with the help of a special equipment known as auger. The night soil undergoes purification by anaerobic digestion and is eventually converted into a harmless mass.

Dug well latrine: It is an improvement over the bore hole latrine. A circular pit about 75 cm in diameter and 12 ft deep is dug into the ground for the reception of the night soil. The action of the dug well latrine is the same as bore hole latrine, i.e., anaerobic digestion.

Water seal latrine: It is further improvement in the designing of sanitary latrines for rural families. Here, the squatting plate is fitted with a water seal which prevents access to flies and escape of odours and foul gases and thereby eliminates the nuisance of smell. The household sewage is admitted into septic tank for treatment. It is water-tight masonry tank, a satisfactory method by which excreta and liquid waste can be disposed. It is suitable for individual dwellings, small groups of houses and institutions.