Introduction

Why is it important?

Safe disposal of greywater resulting from bathing or washing (dishes, laundry etc.) and of blackwater (sewage) is key to maintaining hygiene conditions and preventing the spread of diseases in a settlement. Inadequate treatment of such waste before it is recycled back into watercourses can also increase tensions with neighbouring communities and local government which can consider the settlement a source of disease and pollution. This can be exacerbated by behavioural habits of open defecation of humans or animals.

Sanitation Checklist

  • Do you understand the environmental issues (have you carried out a rapid environmental assessment)?
  • Have you researched the practicality of using alternatives for those activities that may impact on the environment e.g. agroforestry in replace of mono-culture?
  • Can you monitor and respond to the results?
  • Can you make a good case study from the work you have done?
Case Study

Environmental Impact

Providing appropriate sanitation is a humanitarian imperative. But contaminating other water bodies through treatment of sewage could increase tensions, pose human health risks and increase the future costs of providing clean water.

Water pollution

The high influx of displaced people (and their animals) into a single location can significantly increase the amount of greywater and blackwater produced per day. Both types of water contain organic material which has a level of Biological Oxygen Demand (BOD) as it decays via micro-organisms. If this water is released untreated into watercourses, this oxygen demand leads to a decrease in the dissolved oxygen in the watercourse, making it uninhabitable to organisms existing in the water. Thus water quality becomes degraded and ecosystems destroyed.

Aside from organic material, waste water can also include solid inorganic material, toxic chemicals and even radionuclides. While greywater does not contain as much organic material as blackwater, it can still contain chemicals from cleaning products.

Simple latrine facilities, such as pit latrines, could become point sources of pollution if they are allowed to come in to contact with ground water.

Sewage can also contain pathogens which if not treated properly, can spread infections to people and other animals.

In the case of sewage treatment facilities on site (mechanical or natural), run-off, spillage or leakage can also contaminate water bodies. Thus making the treatment plant a point source of pollution.

More Water Pollution info
Water Pollution

Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater). Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compound.

Water pollution reduces security for a population by contaminating otherwise available clean water. It also increases stress on non-polluted water supplies which would antagonise local populations and increases costs due to a need to import fresh water – this also leads to greenhouse gas emissions

Air pollution

If not adequately drained, untreated, foul smelling sewage can cause air pollution and subsequent discomfort and distress. Unpleasant site and smell of water treatment facilities can also have an impact on living conditions of people.

more Air Pollution info
Air Pollution

Air pollution is the introduction into the atmosphere of chemicals, particulates, or biological materials that cause discomfort, disease, or death to humans, damage other living organisms such as food crops, or damage the natural environment or built environment.

Household air pollution can have a significant impact on the a population’s respiratory health.

Mitigation Strategies

The 3 Rs of sustainability can guide mitigation strategies towards:

  • Reduction – of contamination levels in water sources;
  • Reuse – organic matter can be treated and used to improve the nutrient content of soils; and
  • Recycling – solid inorganic wastes such as sand and silt can be used in agriculture or construction.
Greywater recycling

Shelter and settlement designs should include drainage systems for greywater. Greywater is not as environmentally harmful as blackwater, and therefore once passed through gravel filters and leach-fields (removing contaminants and impurities), it can be reused for activities which do not require high quality water – for example for toilet flushing or cleaning, irrigation and construction. This has the benefit of reducing the settlement’s demand for clean water, and the cost of treatment.

Beneficial use of treatment waste

Wastewater treatment produces waste which can have various uses. With Eco-san toilets for example, liquid human waste can be used as a fertiliser and natural pesticide, while solid waste can after being left to decompose in a pit for a period of time, can be used as a soil conditioner.

Slurry produced from the water treatment process can itself be used as fertiliser, or be left to undergo digestion producing biogas which can be used as a fuel for cooking or heating.

Non-organic materials, such as sand, silt and gravel, can also be used in agriculture or as construction materials.

Disposal of water treatment sludges

Water extracted from local aquifers may be contaminated in various ways such as:

  • faecal coliforms;
  • heavy metals;
  • toxic contaminants such as arsenic of fluoride; or
  • even radio nuclides.

The process of treatment will produce sludge with a high concentration of these contaminants and this must be dealt with effectively. Organic content can be introduced to general faecal sludge treatment but non-organics such as heavy metals or toxic elements must be disposed of to appropriate landfill sites where the risk of contaminating local aquifers is negligible.

Greywater recycling

Shelter and settlement designs should include drainage systems for greywater. Greywater is not as environmentally harmful as blackwater, and therefore once passed through gravel filters and leach-fields (removing contaminants and impurities), it can be reused for activities which do not require high quality water – for example for toilet flushing or cleaning, irrigation and construction. This has the benefit of reducing the settlement’s demand for clean water, and the cost of treatment.

Beneficial use of treatment waste

Wastewater treatment produces waste which can have various uses. With Eco-san toilets for example, liquid human waste can be used as a fertiliser and natural pesticide, while solid waste can after being left to decompose in a pit for a period of time, can be used as a soil conditioner.

Slurry produced from the water treatment process can itself be used as fertiliser, or be left to undergo digestion producing biogas which can be used as a fuel for cooking or heating.

Non-organic materials, such as sand, silt and gravel, can also be used in agriculture or as construction materials.

Disposal of water treatment sludges

Water extracted from local aquifers may be contaminated in various ways such as:

  • faecal coliforms;
  • heavy metals;
  • toxic contaminants such as arsenic of fluoride; or
  • even radio nuclides.

The process of treatment will produce sludge with a high concentration of these contaminants and this must be dealt with effectively. Organic content can be introduced to general faecal sludge treatment but non-organics such as heavy metals or toxic elements must be disposed of to appropriate landfill sites where the risk of contaminating local aquifers is negligible.

Additional Resources

American Red Cross and WWF Green Recovery and Reconstruction Training Toolkit – Module 7, Green Guide to Water and Sanitation.

The WASH Section of UNEP’s Main streaming the environment.

Sustainable Sanitation Alliance.

Global Wash Cluster’s Environment in WASH documentation.

UNICEF – Excrete disposal in emergencies.

ProAct Network – water and sanitation.

United Nations Environment Programme & Groupe URD – Module 4: Sustainable water management and ecological sanitation.

From URD/UNEP Training material:

Practical Action – water and sanitation:

UNEP – The WASH Section ‘Main streaming the environment’.

UNEP – Chemicals branch.

Sustainable Sanitation and Water Management Toolbox.

Sustainable Sanitation Alliance.

Global Wash Cluster – Environment in WASH.

Global WASH Cluster – reducing the environmental impacts of vector control chemicals in emergencies.

Inter-Organization Programme for the Sound Management of Chemicals (IOMC).

WHO – Chemical safety.

UNDP – Chemical and waste management.

ILO – Programme on Safety and Health at Work and the Environment (SafeWork).

UNITAR – Chemicals and waste management.

OECD – Chemicals safety and biosafety/a>.

WHO – Guidelines for the safe use of wastwater, excreta and greywater. Volume 4: Excreta and greywater use in agriculture.

WEDC – Wastewater management.