Even with clean sourcing, many drinking water utilities contain some of the common naturally occurring chemicals like chlorine, arsenic, hydrogen sulfide, trihalomethanes, cadmium, nitrate, cyanide, and mercury. Most of these cause adverse health effects.
To add to this, inorganic contaminants such as microbes and algae arise from rocks and sediments through which the water flows. So, let’s look into the various chemicals that contaminate drinking water and the scientific methods available for disinfecting and decontaminating them.1
Common Water-Borne Contaminants
1. Natural Chemicals
Threats to drinking water can appear in any shape or form and may exist in your household, neighborhood, or miles away. The risk of health problems that these contaminants can bring is significant, making it important to know about these chemicals. The most common culprits are chlorine, arsenic, hydrogen sulfide, trihalomethanes such as chloroform, bromoform, and bromodichloromethane formed when chlorine reacts with humic and fulvic acids in raw water, cadmium, nitrate, cyanide, and mercury.
Certain chemicals reach water via general household chemicals being disposed or used for cleaning and laundry. These can also be heavy metals or harsh chemicals like nitrates, which arrive from industrial areas, toilets, and septic tanks that are poorly constructed. Cyanide and mercury can cause adverse health effects and are highly toxic. This can cause water-borne issues such as fertility issues, fetotoxicity, bad pregnancy outcomes, and sperm abnormalities.2 3
2. Microbial Contamination
Infectious diseases are usually caused by the micro-organisms of human and animal excreta. These micro-organisms make their way into your drinking water. This is the cause of some of the most common and widespread health risks associated with drinking water. Contamination of food, hands, utensils, and clothing play a role, particularly when domestic sanitation and hygiene are poor. Improvements in the quality and availability of water in excreta disposal and general cleanliness are all significant in reducing fecal-oral disease transmission.
Some microorganisms and algae that grow in piped water distribution systems may cause diarrhea outbreaks. If drinking water is contaminated by sufficient numbers of these organisms and used by persons who have a weak immune system, they can produce various infections of the skin and the mucous membranes of the eye, ear, nose, and throat.4
Methods To Combat Water Contamination
1. Disinfection
It is highly possible that both ground and surface water are contaminated with bacteria, protozoans, and viruses. We need not further elaborate on the risks you face from this. Standard chlorine chemical disinfection is usually done to disinfect the water, but the harmful byproducts of chlorine make this method questionable.
Bromine is another chemical used for disinfecting that comes with associated health risks. An alternative to the use of chlorine and bromine is the ozone, which has no residual effects associated but produces unknown organic reaction products that can be hazardous to health. Silver is another widely used material for disinfection owing to its low toxicity and antibacterial properties.5
2. Desalination Or Reverse Osmosis
Desalination is the process of removing the salt components of water and making it fit for drinking purposes. The most commonly used desalination techniques include reverse osmosis (RO) and thermal processes. The reverse osmosis system consumes less energy for operation and is a widely accepted method compared to the thermal processes.
RO is applied to a variety of saltwater resources using a tailored pretreatment and membrane system design. Reverse osmosis is capable of removing arsenic, a major toxic chemical found in water, which is the major source of exposure.6 7
3. Carbon Nanotube Absorption Technology
The presence of excessive amounts of metal ions like copper and lead in drinking water may accumulate in the liver, thereby causing gastrointestinal problems. This is where nanotechnology comes into play. Activated carbon with high adsorption capability is an ideal material for removing heavy metal pollutants. Carbon nanotubes are also being actively explored as a means of revolutionizing the use of membranes for water purification.
The water filters use a nanomesh composed of carbon nanotubes on a porous substrate. These nanotubes are a potential means of disinfecting water. They can damage E.coli cell membranes when the cells physically interact with the single-walled carbon nanotubes. They also have a potential to remove the arsenic from drinking water and can desalinate water to a great extent.8
4. Ion Exchange
The ion exchangers used for water softening are solid or gel-like granules that are insoluble in water. Ion exchange is one of the most efficient ways to soften water. Sodium is added to the water to exchange the calcium and magnesium ions in the water with sodium. The calcium and magnesium adhere to a resin in the softener.
The sodium displaces the calcium and magnesium, which is flushed out in a brine solution. When water softeners regenerate, they produce a waste stream that contains significant amounts of chloride into the sewer system in which they are disposed of, including a multitude of downstream water reuse applications like potable water usages and agriculture.9
5. Distillation
The filtration of water through distillation is a very efficient way to remove pollutants from water. Water is boiled to produce steam, which is then cooled and condensed back into the water. Any substances that are not capable of evaporating are left behind in the boiling chamber.
Distillation is very reliable despite being slow and requiring more electrical power to produce a higher quality of water with no decrease in performance over time. Also, the quality of water produced by a distiller will not change over time.10
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