WASH 101

Bangladesh has made good progress in providing basic water services to its people. In Bangladesh, 85% of the people have access to safe water. On the other hand, 40% of the population lack improved sanitation facilities. Recent research on hygiene revealed that most people in Bangladesh have knowledge about hygienic behaviour, but very few people practice it. Contaminated drinking water, poor sanitation and poor hygiene, including menstrual hygiene, are an urgent and growing health problem. It is the leading cause of diarrhoea, which is the cause to one third of the total child deaths in Bangladesh. In addition, faecal sludge management is a big challenge for the South Asian country. Only 2% of faecal sludge is properly treated.

Sanitation refers to public health conditions related to clean drinking water and adequate treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation system aim to protect human health by providing a clean environment that will stop the transmission of disease, especially through the fecal-oral route. For example, diarrhea, a main cause of malnutrition and stunted growth in children, can be reduced through sanitation. There are many other diseases which are easily transmitted in communities that have low levels of sanitation, such as ascariasis (a type of intestinal worm infection or helminthiasis), cholera, hepatitis, polio, schistosomiasis, trachoma, to name just a few.

A range of sanitation technologies and approaches exists. Some examples are community-led total sanitation, container-based sanitation, ecological sanitation, emergency sanitation, environmental sanitation, onsite sanitation and sustainable sanitation. A sanitation system includes the capture, storage, transport, treatment and disposal or reuse of human excreta and wastewater. Reuse activities within the sanitation system may focus on the nutrients, water, energy or organic matter contained in excreta and wastewater. This is referred to as the "sanitation value chain" or "sanitation economy".

Biochemical Oxygen Demand is an important water quality parameter because it provides an index to assess the effect discharged wastewater will have on the receiving environment. The higher the BOD value, the greater the amount of organic matter or “food” available for oxygen consuming bacteria.

Chemical oxygen demand (COD) is a measure of the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals such as ammonia and nitrite.

COD or Chemical Oxygen Demand is the total measurement of all chemicals (organics & in-organics) in the water / waste water; BOD is a measure of, the amount of oxygen that require for the bacteria to degrade.

Typical biodegradable and non-biodegradable fractions for fresh and digested faecal sludge; the figures for readily biodegradable COD are the sum of figures given for acidogenic bacteria, fermentable organic matter, and volatile fatty acids [Source: Lopez-Vazquez et al. (2014: Table 9.3)]