Ensuring potable water security in BD
Water is a renewable resource, dissolves nutrients and transfers them to cell, regulates global temperature, supports structure and removes waste products. Natural stores of water in hydrological cycle are oceans 97.41%, ice caps and glaciers 1.9%, ground water 0.5%, soil moisture 0.01, lakes and river 0.009% and atmosphere 0.0001%. In this planet, 97.5% water is saline where only 0.03% is pure to drink. Climate change, sea-level rising and global warming is changing the total global picture and it is true that third world countries are unable to face these emergency rather than first world countries.
Setting the scene
Water quality" is a technical term that is based upon the characteristics of water in relation to guideline values of what is suitable for human consumption and for all usual domestic purposes, including personal hygiene. Components of water quality include microbial, biological, chemical, and physical aspects.
Microbial Aspects: Drinking water should not include microorganisms that are known to be pathogenic. It should also not contain bacteria that would indicate excremental pollution, the primary indicator of which are coliform bacteria that are present in the feces of warm-blooded organisms. Chlorine is the usual disinfectant, as it is readily available and inexpensive. Unfortunately, it is not fully effective, as currently used, against all organisms.
Biological Aspects: Parasitic protozoa and helminths are also indicators of water quality. Species of protozoa can be introduced into water supply through human or animal fecal contamination. Most common among the pathogenic protozoans are Entamoeba and Giardia. Coliforms are not appropriate direct indicators because of the greater resistance of these protozoans to inactivation by disinfection. Drinking water sources that are not likely to be contaminated by fecal matter should be used where possible due to the lack of good indicators for the presence or absence of pathogenic protozoa. A single mature larva or fertilized egg of parasitic roundworms and flatworms can cause infection when transmitted to humans through drinking water. The measures currently available for the detection of helminths in drinking water are not suitable for routine use.
Chemical Aspects: Chemical contamination of water sources may be due to certain industries and agricultural practices, or from natural sources. When toxic chemicals are present in drinking water, there is the potential that they may cause either acute or chronic health effects. Chronic health effects are more common than acute effects because the levels of chemicals in drinking water are seldom high enough to cause acute health effects. Since there is limited evidence relating chronic human health conditions to specific drinking-water contaminants, laboratory animal studies and human data from clinical reports are used to predict adverse effects.
Physical Aspects: The turbidity, color, taste, and odor of water can be monitored. Turbidity should always be low, especially where disinfection is practiced. High turbidity can inhibit the effects of disinfection against microorganisms and enable bacterial growth. Drinking water should be colorless, since drinking-water coloration may be due to the presence of colored organic matter. Organic substances also cause water odor, though odors may result from many factors, including biological activity and industrial pollution. Taste problems relating to water could be indicators of changes in water sources or treatment process. Inorganic compounds such as magnesium, calcium, sodium, copper, iron, and zinc are generally detected by the taste of water, and contamination with the oxygenated fuel additive MTBE has affected the taste of some water.
State of water bodies in Bangladesh
Our water body is being polluted by agricultural pollutants, industrial effluents, different rivers are losing their life, climate change affects the water table, policy is failing to manage this public goods; onthe other side, corporate elites are trying to use this gap as their interlude of profit. Nowadays, local, national and international companies are doing their water business in our country. After all, quality and access of pure water is lessening day by day due to the rapidly growing population; industrial contamination; slumization; improper use of agricultural synthetic chemicals and pesticides; indiscriminate disposal of municipal wastes, poorly designed flood control and water supply systems, drainage and irrigation works, lack of adequate regulatory measures and institutional setup for proper monitoring and control.
Asian water development outlook, 2016 mentions; 80% wastes are dumping into river in Bangladesh. Water security index indicates Bangladesh is 44th out of 48 countries. Around 250 industries are discharging chemical pollutants into Buriganga and Sitalakka River. Every day four thousand tons solid waste & 22 thousand tons tannery waste mixes with water in Buriganga River. Different industries and their contribution to pollution in Dhaka are : Pulp & paper - 47.4%; pharmaceuticals - 15.9%; Metals -14%; Food industry - 12.1%; Fertilizers/pesticides - 6.6%.
In urban areas, the groundwater laced with harmful chemicals may then be supplied to urban dwellers that are unknowingly exposed to health hazards. Sewages are discharging directly into the rivers and low-lying part around the urban areas. In Dhaka, 20 canals have lost her life out of 43. Heavy metals ? copper, iron, lead, nickel is distressing the BOD, COD, DO, TDS, PH of water. Different projects were taken to recovery the present situation of canal and pond in Dhaka city. Such as, dredging Buriganga River by WASA, dig the daleshawri, pungli-Bangshi and bring water through Jamuna to meet the demand of Buriganga River. But the projects could not see the light of a day.
Eutrophication and bacterial content in lakes and rivers are also high. This is a threat to the health of urban dwellers as river water is also supplied by the "Water Supply & Sewerage Authority" for drinking and other purposes. This is happening in all cities of Bangladesh.Reduction of 'river water flow due to siltation' is increasing salinity at coastal areas. Unplanned shrimp farming creates more salinity affecting the agricultural land and water quality particularlyin Khulna, Satkhira and Bagerhat districts.
To be continued...
The writer is a freelance contributor