15 October 2007

Rwanda: Effects of Improper Sewage Disposal


Kigali — There is a lot of sewage flowing around due to a poor drainage system especially in the areas around Nyabugogo River. We need to look at this problem squarely and find solutions before the health and hygiene of the people living in these areas suffer from diseases associated with this rot.

Sanitation is the worst problem facing the city, which needs to be addressed properly and energetically, otherwise soon or later, we are at risk of an outbreak of water born diseases.

If hygiene is in question and vaccines and treatment ineffective or too expensive, then how can we reduce high mortality and morbidity rates due to infectious diseases?

The answer is to try to improve our state of hygienic practice.

While there have been excellent views on the indiscriminate spiting and urinating in the public places, none has so far addressed the practical consequences for hygiene, whether trends in increased infection justify continued silent on sewage in our city.

When toxic substances enter a body of water, they will be dissolved, become suspended in water or get deposited on the bed of the water body.

The resulting water pollution causes the quality of the water to deteriorate and affects aquatic ecosystems. Pollutants can also seep down and effect groundwater deposits. Sewage and industrial wastes are discharged into the rivers. Because of this, pollutants enter groundwater, rivers, and other water bodies.

Such water, which ultimately ends up in our households, is often highly contaminated and can carry disease-causing microbes.

Domestic sewage contains a wide variety of dissolved and suspended impurities. It amounts to a very small fraction of the sewage by weight, but it is large by volume and contains impurities such as organic materials and plant nutrients that tend to rot.

The main organic materials are food and vegetable wastes. Plant nutrients come from chemical soaps, washing powders, etc.

Domestic sewage is also very likely to contain disease-causing microbes.

The various substances that we use for keeping our houses clean add to water pollution because they contain harmful chemicals. Most detergents and washing powders contain phosphates, which are used to soften the water, among other things.

These and other chemicals contained in washing powders affect the health of all forms of life in the water. When sewage enters a lake or stream, micro organisms begin to decompose the organic materials. Oxygen is consumed as micro organisms use it in their metabolism.

Ecological Damage:

Sewage-contaminated water causes eutrophication, which is the increase in concentration of chemical elements required for life. The nitrates, phosphates, and organic matter found in human waste serve as food for algae and bacteria.

This causes these organisms to overpopulate to the point where they use up most of the dissolved oxygen that is naturally found in water, making it difficult for other organisms in this aquatic environment to live. The bacteria are basically strangling the other organisms.

Some of the organisms that do overpopulate from this can also be disease-causing micro organisms.

Phosphates are also found in soaps and detergents, but there are other household products that we use everyday that can be toxic to many animals and humans if they are dumped directly into a water body.

Health Risks:

A variety of organisms live in the human gastrointestinal tract. These organisms including bacteria, viruses, and parasites, end up in human waste. Many of these organisms can be transmitted to other humans and animals.

Bathers are at increased risk of contracting illness due to bacteria and viruses present in sewage effluent. Gastrointestinal disorders have been linked to sewage pollution, with viruses implicated as the cause. Shellfish strain water through their gills to trap microscopic plants and animals for food.

If the water was contaminated with disease-causing bacteria, these could be consumed as food by shellfish. When eaten raw or partially cooked, these shellfish can make people sick.

Certain fish in contaminated waters can accumulate high levels of toxic substances. When these foods are consumed frequently over a lifetime, they may increase the consumers' risk of adverse health effects. Detergents can cause liver and kidney damage, while sewage water carries diseases such as Giardiasis, Amoebic dysentery and Cholera.

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