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Chemical Oxygen Demand is similar to BOD but measuring the amount of oxygen consumed by a chemical oxidizing agent. COD is always equal to or higher than BOD because of the organic compounds which can only be oxidized chemically.


meets the needs of the present without compromising the ability of future generations to meet their own needs (Brundtland Commission)

Environmental remediation

As oppossed to simply ‘sanitation', seeks to include all aspects of the physical environment which may affect human health and well-being; typical examples of an environmental sanitation program may include potable water, solid waste management, drainage, storm water management, and sanitation.


A general term used to describe a battery of actions that all aim to reduce the spread of pathogens and maintain a healthy living environment. Specific actions related to sanitation include, wastewater treatment, solid waste management and storm water management.


Actor / Stakeholder

Any group, person, or agency that has an interest in or is affected by a policy, plan, or project.


African Water Association


means ‘in the absence of oxygen'. Aerobic processes are either hindered, or halted by the presence of oxygen. anaerobic processes are often more foul-smelling than aerobic processes.


means ‘deficient in oxygen'. Organisms that can live in an anoxic environment can use oxygen that is bound in other molecules (e.g. nitrate, sulphate). Anoxic conditions are often found at the interface between aerobic and anaerobic environments (e.g in trickling filters or in facultative ponds).



bacteria are simple, single cell organisms. Bacteria obtain nutrients from their environments by excreting enzymes which dissolve complex molecules into more simple ones that can then pass through the cell membrane. Bacteria live everywhere on earth and are essential for maintaining life and performing essential ‘services' such as composting, aerobic degradation of waste, and digesting food in our stomachs; some types however can be pathogenic and cause severe illness.


can be broken down into basic molecules (e.g. carbon dioxide, water) by organic processes carried out by bacteria, fungi, and other microoganisms.


The common name for the mixture of gases released from anaerobic digestion. Typically biogas is comprised of methane (50-75%), carbon dioxide (25-50%) and varying quantities of nitrogen, hydrogen sulphide, water and other components.


refers to the quantity of living organisms. It is often used to describe the ‘active' part of the sludge that is responsible for degrading the organic matter.

BOD / Biochemical oxygen demand

It is a measure of how much oxygen is consumed by microbes as they degrade organic matter. It is a proxy measure for the amount of organic material that is present in water: the more organic content, the more oxygen required to degrade it (high BOD), the less organic content, the less oxygen required to degrade it (low BOD)

Brown water

The mix of faeces and flushing water, but with NO urine



The process of forming small clumps so particles so that they may be more easily settled out of wastewater.


Compost/ Humus is the earth-like, brown/black material that is the result of decomposed organic matter; generally is has been hygienized sufficiently that it can be used safely in agriculture.


The controlled aerobic degradation of organic matter by bacteria, fungi, worms, and other organisms to create a sanitized, humus-like product. The composting process is characterized by a sharp, and persistent heat change that can raise the temperature of the compost pile up above 70 degrees C.


A mixture of cement, sand, gravel and water that will harden into a solid, stone-like material.



The shift of decision making and responsibility from central authorities to the same level at which the policies are directed.


The transformation of dead organic material (plants, animals, etc.) into more basic compounds and elements.

Drainage sludge

Faecal Sludge is the general term for the undigested, or partially digested slurry or solid that results from the storage or treatment of blackwater or excreta

Duration or time of retention or stay

The theoretic time that one unit of water (or sludge) stays in one tank or pond. When referring to units of water, the term Hydraulic retention time is often used (HRT) and is calculated by: HRT= V/Q, where V is the volume of the tank and Q is the rate at which the water leaves (e.g. m 3 /sec).


Ecological sanitation

Ecological Sanitation is a term applied to waste treatment technologies when they not only limit the spread of disease, but protect the environment and return nutrients to the soil in a beneficial way.


Hunting water

Flushwater is the water that is used to move excreta, urine or faeces from the user interface into the next process technology.



Liquid and solid material pumped from a septic tank, cesspool or other primary treatment source'. (Bellagio, 2005)



A micro-organism that is capable of causing disease in plants or animals (including humans).

Pipeline / Sewerage network

All the components of a system used for collecting, transporting and treating sewage (including pipes, pumps, tanks, etc.).


Sustainable sanitation

The main objective of a sanitation system is to protect and promote human health by providing a clean environment and breaking the cycle of disease. In order to be sustainable a sanitation system has to be not only economically viable, socially acceptable, and technically and institutionally appropriate, it should also protect the environment and the natural resources (SuSanA).