Household Excreta Disposal system

Types of Household Excreta Disposal system in Sri Lanka

The purpose of an excreta disposal system is to carry human excreta back to the nature, providing comfort and convenience to the users. In the process there should be minimal risk of excreta-related diseases to humans and livestock and minimal pollution of the environment. Therefore an excreta disposal system is a must by nature.

In Sri Lanka, major challenges with environmental health is that of excreta and refuse disposal system appropriate to low-income communities and high-density for some instance. The on site disposal system that is by far the most convenient for these situations is the conventional water-borne sewage system where the excreta of household are retaiened, stabilized and disposed of, within the premises of individual household is being widly used in rural areas. The different types of on site excreta disposal systems more generally used as follows :

# Simple Pit Latrines

# Water Sealed Pour-Flush Latrines

# Dry Compost Latrines (EcoSan Toilets)

Simple Pit Latrine

The pit latrine is the most common method of on site excreta disposal system. Good pit latrines provide similar health benefit to sophisticated sewage system at very much lower cost. There are several forms of pit latrine. Selection of the most appropriate type depends partly on the local situation including, the ground water table, the tradition and cultures of the users. Material used for anal cleaning after defecation is yet another factor to be considered. However, in Sri Lanka mostly water is used for this purpose as a general practice.

In all types of pit latrine excreta falls directly or indirectly to a hole in the ground or into the built pit. In the pit excreta decompose. With the decomposition gases given of like Carbon Dioxide and Methane escape to the atmosphere or are the absorbed by the soil. Suspended particles in the water infiltrate through the bottom and the sides of the pit into the surrounding soil. A solid residue accumulates in the pit gradually coming to the soil on decomposition.

The most common complaints about unsatisfactory latrines are nuisance from flies and bad smells. Flies are also one of the main agents for the transmission of faeces-derived diseases. Female flies lay their eggs on faeces. Newly hatched flies in great numbers emerge from an open pit carrying partial of faeces to their next meal, which may b on human food. In a pit latrine where urine and water used for anal cleaning are falling in to the pi there is the possibility for mosquitoes breeding too, in the pit. Therefore, for the better control of flies and smells water sealed pour flush latrine are effective for comparatively shallow pits also.

Water Sealed Pour-Flush Latrine

This is the most commonly used type of latrine in Sri Lanka where water is used for anal cleaning. Poor flush latrines have a pan with a water seal fitted onto the squatting plate, which is clean by pouring in water. About three liter of water is usually sufficient for flush clearing the pan and the seal after every use. Almost a similar quantity of water may be required for anal cleaning after defecation.

In this method the superstructure is not erected on the top of the pit. Instead the pit is located away from the cabin and the pour flush ceramic pan with the water seal is connected to the pit with a smooth bore pipe usually earthenware or PVC laid to a slop of not less than 1 in 40. This type could be installed indoors since it is free from both unpleasant smell and the nuisance of flies and mosquitoes provided it is seen clean, at all time.

Dry Compost Latrines (EcoSan Toilets)

The dry compost latrine can be identified as a more environment friendly type of excreta disposal system where the use of decomposed pit content as a resource is design and built to keep the faeces separate form urine and the water used for anal cleaning. In this case special emphasis is placed on providing a separate place for washing and measures are taken to ensure that the waste water is drained away without getting into the pit. Usual design is to orient the wash place such a way that the urine gets diluted with the wash water on the way to its disposal area, thus facilitating reduction of bad odors. The latrine is usually elevated construction (stepped-up) with the pit fully lined making it watertight and always in two compartment vaults for alternate use. Unlike the other types of latrines there are no effluent discharges from the pit of a dry compost latrine to the surrounding area. The urine - which is liquid fertilizer – diluted with the anal cleaning water can be conveniently drained into an evaporative plant bed or a cultivation plot where it will be effectively used by plants. To eliminate bad odours and the nuisance from flies a handful of ash, lime or fine soil has to be spread into the pit covering the fresh excreta after every use and the squat hole has to be covered with the lid provided at all times not in use. It takes over a year for complete decomposition of the content in a pit before it converts itself into compost itself into compost.

Design this way, a dry compost latrine will be highly effective and more appropriate solution to sanitation in high water table areas and water logged areas. Due to its water conserving technology the dry composed latrine can be effectively used in areas with a scarcity of water resources.

When the in use fills up to about three quarters of the depth it has to be put out of use. A layer of soil is spread over the content and the squad hole is sealed up with the lid. The contents are allowed to decompose. Normally within six months of a time the fecal matter decomposes into a compost resembling rich garden soil with no objectionable odour or appearance.