How water gets contaminated?
This is a really simple incident that cause a devastating result. All those toxic chemicals emitted to atmosphere are then pours back to earth with rain, contaminates water bodies and soil. Those that are absorbed into soil, may it be through rain or direct spray to earth such as pesticides, are then seep in to ground water and comes back to us through wells.
Water can get contaminated with microorganisms, biotoxins, heavy metals and other toxic chemicals.
Effects of climate change on water
In addition to water contamination due to anthropogenic chemicals, Climate change is another driver behind water contamination and thereby, waterborne diseases. Intensive rain as well as intensive droughts resulted by climate change, cause increase and spread of various pathogenic bacteria and virus.
In addition, droughts can concentrate the chemical contaminants in water. flooding due to heavy rains can result in water contamination through mixing with sewage systems and thereby increase the exposure to waterborne diseases. In addition, melting glaciers due to increased temperature can result in releasing chemicals trapped in them to oceans and thereby contaminate the marine life.
Contaminated water can be a cause for many diseases [1, 2]
Water can be a media that cause diseases related to heavy metals and other hazardous chemicals. In addition, there are some diseases directly related to water contaminated with pathogens.
- Lead poisoning
- Lymphatic filariasis
- Hookworm infection
- Ring Worm or Tinea
- Cyanobacterial toxins
- Japanese encephalitis
*** I recently came across this study on “DRINKING WATER AND CHILDREN’S HEALTH” By Sonya Lunder, Senior Analyst, EWG. Gives an alarming message.
Standards for drinking water
Indicated below are the standards for drinking water set by World Health Organization and by different countries .
|Parameter||World Health Organization||European Union||United States||China||Canada|
|Antimony||ns||5.0 μg/l||6.0 μg/l||“||“|
|Benzene||10μg/l||1.0 μg/l||5 μg/l||“||“|
|Benzo(a)pyrene||“||0.010 μg/l||0.2 μg/l||0.0028 μg/l||“|
|Bromate||“||10 μg/l||10 μg/l||“||“|
|Cadmium||3 μg/l||5 μg/l||5 μg/l||5 μg/l||“|
|Chromium||50μg/l||50 μg/l||0.1 mg/L||50 μg/l (Cr6)||“|
|Copper||“||2.0 mg/l||TT||1 mg/l||“|
|Cyanide||“||50 μg/l||0.2 mg/L||50 μg/l||“|
|1,2-dichloroethane||“||3.0 μg/l||5 μg/l||“||“|
|Fluoride||1.5 mg/l||1.5 mg/l||4 mg/l||1 mg/l||“|
|Lead||“||10 μg/l||15 μg/l||10 μg/l||“|
|Mercury||6 μg/l||1 μg/l||2 μg/l||0.05 μg/l||“|
|Nitrate||50 mg/l||50 mg/l||10 mg/L (as N)||10 mg/L (as N)||“|
|Nitrite||“||0.50 mg/l||1 mg/L (as N)||“||“|
|Pesticides (individual)||“||0.10 μg/ l||“||“||“|
|Pesticides — Total||“||0.50 μg/l||“||“||“|
|Polycyclic aromatic hydrocarbons l||“||0.10 μg/||“||“||“|
|Selenium||40 μg/l||10 μg/l||50 μg/l||10 μg/l||“|
|Tetrachloroethene and Trichloroethene||40μg/l||10 μg/l||“||“||“|
Drinking safe water
Water purification systems made a devastating rise in sale once in Sri Lanka, when it was announced that CKDue (Chronic Kidney Disease due to unknown etiology) is caused by water. Marketing wise, one may think this as a promotion. But I only want to mention, to what extent your water purifier can clean your water.
Table 1: Water purification systems, their efficiency in purifying and mechanisms [4, 5, 6, 7,8].
|Water purification method||What it filters off||Mechanism of purification|
|SODIS( “Solar water disinfection”)||The UV-A rays in sunlight kill germs such as viruses, bacteria and parasites (giardia and cryptosporidia).||Clear PET bottles are filled with the water and set out in the sun for 6 hours.
|Boiling||Kills Pathogens, drives out some of the Volatile Organic Compounds (VOCs)||Place the water in a clean container and bring it to a full boil and continue boiling for at least 3-5 minutes. Boiled water should be kept covered while cooling. If the water is cloudy, filter before boiling.|
|Distillation||Nitrates, chloride, and other salts, sediment, metals,||The water is boiled in a chamber causing water to vaporize, and the pure (or mostly pure) steam that moves to a different part of the unit, is cooled until it condenses back into liquid water.|
|Sediment Filters||Asbestos fibers, cysts and some organic particles||Fiber or Ceramic filters provide mechanical filtration|
|Activated Carbon Filters are of two types
|Contaminant particles are removed by filtration and adsorption to the surface of the carbon particles. But, hot water can release trapped contaminants into the water stream|
|1. Granular Activated Carbon (GAC)||Can reduce chlorine and particulate matter as well as improve the taste and odor of the water.|
|2. Solid Block Activated Carbon (SBAC)||Pesticides, herbicides, chlorine, chlorine byproducts and particulate matter such as parasitic cysts, asbestos, etc
|Reverse Osmosis (RO)||Protozoa (Cryptosporidium, Giardia), bacteria (Campylobacter, Salmonella, Shigella, E. coli), viruses (Enteric, Hepatitis A, Norovirus, Rotavirus), chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.
Asbestos, and all of the cancer-causing “radionuclides”
***Some pesticides, solvents and other volatile organic chemicals (VOCs) are not completely removed by RO. A good activated carbon post filter is recommended to reduce these contaminants .
|a separation process which uses water pressure (in excess of the osmotic pressure) to force water molecules through a semipermeable membrane.|
|KDF (Kinetic Degradation Fluxion)
|Removes chlorine, Kill algae and fungi, Controls bacterial growth in the filter, Remove hydrogen sulfide, iron, lead, cadmium, aluminum, mercury, arsenic and other inorganic compounds, Partially reduce hardness
***Do not, by themselves, remove organic chemicals (pesticides, disinfection byproducts, MTBE, etc.), or parasitic cysts
|Atmospheric Water Generators (AWG)||Removes virtually all bacteria and common viruses, remove volatile organic chemicals. VOCs such as ether, viruses, bacteria, VOCs, inorganic chemicals, dirt, pollution and residual chlorine.||A condensation unit receives a clean humid airflow and condenses water vapor into liquid.|
|Activated Alumina||reduce levels of fluoride, arsenic, and selenium without using distillation or reverse osmosis.
****Activated alumina devices can accumulate bacteria, so treated water may have higher bacteria counts than raw water.
|Water containing the contaminant is passed through a cartridge or canister of activated alumina which adsorbs the contaminant .|
Those are what came with new technologies. In Sri Lanka, there are natural seeds that does more or less similar job.
- Several researches shows that Moringa oleifera seeds (Sinhala: Murunga) are efficient in removing heavy metals such as cadmium, copper, chromium, and lead from water .
- Dried Vitex negundo leaves is the best way to reduce Total Solids in untreated water and bring it to the standard level .
- Caesalpinia bonduc (Sinhala: Kumburu) seeds (traditional method of removing water hardness existed among ancients in Sri Lanka)
To conclude with, I would suggest that first thing we need to be doing is to check the water source to understand what it is contaminated with and then go for the best suitable purification method.
- Waterborne Diseases, Health Impacts of Climate Change, National Institute of Environmental health science (accessed January, 2017) https://www.niehs.nih.gov/research/programs/geh/climatechange/health_impacts/waterborne_diseases/
- Water-borne Diseases: types and information, Disabled World (accessed January 2017) https://www.disabled-world.com/health/water-diseases.php
- SODIS (accessed January 2017), http://www.sodis.ch/methode/anwendung/index_EN
- A Guide to Drinking Water Treatment Technologies for Household Use, Centers for Disease Control and prevention (accessed January 2017), https://www.cdc.gov/healthywater/drinking/home-water-treatment/household_water_treatment.html
- What Does a Top-Quality Reverse Osmosis System Remove from Tap Water?, Pure Water Products, LLC (accessed January 2017), http://www.purewaterproducts.com/articles/what-does-ro-remove
- Drinking Water Treatment Methods, Drinking Water Resources (accessed January 2017), http://www.cyber-nook.com/water/solutions.html#ion
- Comparison of Treatments and Options for Drinking Water, Air 2 water (accessed January 2017), http://www.air2water.biz/compare-water-purification-systems.html
- Heavy Metal Removal from Water using Moringa oleifera Seed Coagulant and Double Filtration, Ravikumar K, Prof.Sheeja A K, (accessed January 2017) http://www.ijser.org/researchpaper%5CHeavy-Metal-Removal-from-Water-using-Moringa-oleifera-Seed-Coagulant-and-Double-Filtration.pdf
- Withanage, S., Tissera, D., Gihan,M.,Traditional ways of water purification, First National Symposium on the Potential Health and Environmental Impacts of Exposure to Hazardous Natural and Man-made Chemicals and their Proper Management, 2012, 34-40.