Water treatment

Water – a chemical compound of hydrogen and oxygen, without which life would not exist. Water is both the main component of living organisms and the living environment for many of them. It is omnipresent in industry, agriculture and everyday life. Necessary for normal functioning of households, health care facilities, catering, construction – every area of life. The consequence of the demand for water is the need for its treatment for various purposes.

What is water treatment

Water treatment is the process of bringing contaminated water to a state in which it can be used for its intended purpose and in accordance with demand. The main reason for treatment is to remove mechanical impurities from the water, which are caused by rust, sand, silt and other organic and inorganic deposits in the water supply, well water and surface water. Contaminating sediments have a negative impact on the quality of water used, including its clarity and pH.

Water quality parameters depend on many factors: place of intake, groundwater level, etc. There is no universal method of water treatment, as there are various causes of pollution. Water can be treated mechanically, chemically and biologically and the choice of the most effective treatment method(s) should be made individually, based on the results of water intake tests.

Water treatment methods are also different depending on the purpose of water. Water is treated in a different way for drinking and hygienic purposes in households, for heating systems, for industrial applications and for laboratory purposes. The issues of water treatment are regulated by a number of regulations, including the Regulation of the Minister of Health on the quality of water intended for human consumption of 7 December 2017 (Journal of Laws of 2017, item 2294), the Act of 14 March 1985 on State Sanitary Inspection (Journal of Laws of 2019, item 59), the Act of 20 July 2017 Water Law (Journal of Laws of 2018, item 2268).

The human body needs not only water to function properly, but also the substances in it – macro- and microelements and sub-components. For example:

Bicarbonates – stimulate the acid-base balance in the digestive tract, regulating digestive processes.
Sulfates – sulfur compounds are components of some enzymes.
Chlorides – chlorine is a component of gastric juice and also maintains normal osmotic pressure in cells.
Sodium – in adequate amounts is necessary for water exchange in cells and regulates muscle contractions. Excess sodium (hypernatremia) causes increased blood pressure, headaches and palpitations.
Potassium – regulates cellular water levels, osmotic pressure, maintains fluid balance in the body and adequate blood pressure.
Calcium – main component of bones and teeth, affects muscle and nerve function, regulates heart function.
Magnesium – important in the process of building bone and muscle cells, involved in the formation of enzymes.
Iron – participates in the oxidation process, prevents anemia; most of it is bound in hemoglobin. Excess iron causes fatigue, joint pains, digestive problems, gray coloration of the skin, especially the face.
Fluoride – a component of bones and teeth, prevents caries, strengthens the enamel. However, excess fluoride is harmful; it causes a disease called fluorosis, resulting in e.g. erosions on the enamel.
Manganese – in small amounts, it is a component of enzymes metabolizing glucose and fatty acids and is important in fertility. Excess can cause liver, thyroid and brain cell dysfunction.

Water treatment aims to reduce the content of certain minerals to a level that allows the water to be used for its intended purpose.

Waterborne diseases

Around the world, waterborne diseases pose a major threat to both humans and livestock. According to the World Health Organization report, 88 percent of waterborne diseases are caused by poor hygiene and sanitation as well as the widespread use of untreated water.

Waterborne hazards are divided into two categories:
Chemical hazard and industrial contamination
Biological and microbiological hazards

Chemical hazards and industrial contamination are caused by compounds and chemicals entering the water from industry, agriculture, municipal wastewater, transportation, and finally fuel pipeline and tanker failures. Pollution of industrial origin is caused mainly by heavy metal compounds – mercury, cadmium, chromium, lead, detergents, hydrocarbons, phenols. Agriculture, on the other hand, generates pollution mainly with nitrates, phosphates and chlorides, coming from plant protection products (pesticides) and fertilizers.

A distinction is made between point pollution, where pollution enters the water at a single point (e.g. sewage), and area pollution, where surface and groundwater contamination occurs over a larger area (large agricultural areas, seas). Pollution is also caused by eutrophication. It is a process of increasing water fertility, leading to intensive growth of aquatic vegetation and phytoplankton, which in turn causes accumulation of sludge at the bottom of the water body. Anaerobic bacteria multiply in it, forming hydrogen sulfide, which destroys living organisms at the bottom of reservoir. Eutrophication also results in increased phosphate release and oxygen depletion in the water.

Diseases that threaten as a result of the above pollution are associated with an excess of certain chemical elements that enter the body with water and damage the functions of various internal organs.

Biological and microbiological hazards arise primarily when human and animal excrements or decomposition products enter the water. There are many diseases transmitted this way and some of them are life-threatening. It can be a simple digestive indisposition that spontaneously disappears, but it can also be viral gastroenteritis, typhoid fever, meningitis, hepatitis, polio, cholera, and others.

Fecal matter is especially dangerous because of the helminthiasis. Drinking water that has been contaminated with human feces can result in the infection of ascariasis. The eggs of roundworms (also pinworms and whipworms) float freely in water, e.g. in rivers or lakes, and can be swallowed accidentally while bathing.

A very dangerous parasite is the liver fluke. This is a fluke, the larvae of which live on aquatic plants and can enter the human body. When swallowed, the larvae transform into the adult form, which finds its final location in the bile ducts, causing mechanical jaundice due to bile duct obstruction, a life-threatening condition.

Lamblia is a microscopic protozoan that lives in the human small intestine, which it enters after consuming water containing cysts. Symptoms of lambliosis include recurrent inflammation of the gastrointestinal tract, nausea, abdominal pain and stinking, watery diarrhea.

Another problem is hard water, which contains too many calcium and magnesium compounds. Although it does not cause disease, it has a negative impact on the taste of meals prepared, the longevity of heating elements in household appliances due to intense scale formation and the condition of clothes, which quickly lose their color due to inefficient use of washing agents that do not dissolve well in hard water.
The most important thing is prevention; diseases can and should be prevented with water treatment. This is particularly important in larger populations. Drinking water must first be thoroughly tested and then treated with suitable equipment.

What influences water quality deterioration

Before civilization settled on the Earth for good, all water pollution was of natural character – it resulted from the processes of metabolism in nature; it included the organic remains of plant or animal origin getting into water, substances washed out by watercourses (minerals, minerals), etc. Precipitation also had a certain role, which washed out various substances from the surface and then got into water reservoirs.

With the man’s rule, the factors of water quality deterioration started to increase rapidly. Agriculture, communication, and finally industry were developed. Many new substances began to get into the water, causing changes in its physical and chemical properties. This includes plant protection products (pesticides) and chemical fertilizers. Industrial plants generate wastewater, which was initially discharged directly into rivers, causing serious havoc to the natural aquatic flora and fauna. One example is the complete disappearance of noble fish species such as sturgeon and salmon in Polish rivers, which were also prevented from migrating upstream to spawn by the construction of dams. Pollution has also caused a strong decline in the populations of native noble crayfish, which live mainly in lakes of high water purity class, and the emergence of an invasive species – American crayfish, resistant to the presence of harmful substances in water.

Secondary water pollution is also a negative factor; although water supply companies provide water quality that meets current standards, it can become secondarily contaminated during flow to the consumer, mainly microbiologically – parasitic infections can occur. The causes are to be found in the quality of water pipes, both from the material, manufacturing and maintenance point of view. They can be made of inadequate materials, their poor condition can result in water ironing, cause discoloration or give foreign odors. They may also be leaking, resulting in the entrance of mechanical contaminants that build up in the pipes and contribute to the development of sediments that promote the growth of microorganisms.

According to the law, water companies prevent microbiological contamination by using disinfectants (mainly chlorine), but this causes organoleptic changes that can be felt. The water hardness, resulting from high levels of calcium and magnesium, is also noticeable, and can be seen in the form of sediment and quick scale deposits on household appliances and “under-washed” clothes. Iron and magnesium compounds, in turn, give water an unpleasant, “ferrous” taste and leave brown sediment.

For many years, efforts have been made to restore proper water quality. It is not possible to completely eliminate water pollution, but it can be significantly reduced through rational waste management and proper waste disposal, building sewage treatment plants and treating water on our own, using various solutions. These may include water filters, water treatment plant, UV disinfection, etc. The treatment method should be chosen after the water has been tested.

How to recognize contaminated water

The only reliable method to determine the quality of water in our home is to have it tested, regardless of whether we use the water supply or have our own intake (well), although in the latter case it is absolutely necessary. At home, you can rely only on the organoleptic test, which can show exceeded levels of iron and manganese, hardness, turbidity and discoloration. However, it will not find, for example, microbiological contaminants that may penetrate into the well water and tap water. The basic parameters to be tested are:

pH – drinking water should have a pH range of 6.5 – 9.5 (about 7 is neutral). Too low pH indicates the presence of carbon dioxide dissolved in water, which has acidifying properties. It should be noted that acidic water causes corrosion of copper, so at low pH it is better to use pipes made of another material.
Turbidity (the inverse of transparency), expressed in NTU (Nephelometric Turbidity Unit). For drinking water, this indicator must not exceed 1 NTU. The turbidity of water is affected by sediments – clay, silt, mineral and organic matter, as well as plankton and other microorganisms.
Color – measured in mgPt/dm3, or in degrees of the platinum-cobalt scale; one degree corresponds to the color given by 1 mg of platinum in the form of salt dissolved in one liter of water. The measurement should not show more than 15 mgPt/dm3, although, following a change in regulations, no specific degree is given nowadays, and the requirement of acceptability of the color by consumers is applied. This parameter is of particular importance in the case of excessive water carbonation.
Odor – analyzed according to a five-grade scale, cold or hot: 0 – no odor, 1 – very weak odor, 2 – weak, 3 – distinct, 4 – strong, 5 – very strong. In terms of origin, the odor is marked with letters: R – plant odor without signs of decay, G – decay odor of natural origin, S – odor of unnatural origin. It is also possible to mark specifically – the odor of hydrogen sulfide, ferrous, petroleum, etc. According to the regulations, the odor should be acceptable.
General hardness – hard water is easy to recognize in the home due to the deposition of scale and sediment, especially on the heating elements of washing machines, kettles, dishwashers, etc. Scale also has a negative effect on skin and hair, laundry loses its color intensity and becomes unpleasant to the touch. Hard water requires greater use of cleaning agents, and its taste is not liked by everyone.
Iron and manganese – their excess in the water essentially changes its smell and taste, but also its color – it becomes beige to brown, with iron tinting more brown and manganese black. Sediment accumulates in the pipes, which reduces light, resulting in increased energy consumption by the pumps. Microorganisms can grow in the sediment, which can lead to secondary water contamination.
Ammonia – its presence may indicate that the water is contaminated with decomposition products of organic matter, which would suggest sewage entering the water. Testing in this situation will also show increased bacterial counts and concentrations of other forms of nitrogen.
Nitrates and nitrites – enter the water as a result of organic matter mineralization and nitrification processes, nitrogen fertilizer pollution, or septic tank effluent.
Bacteria – their presence can only be demonstrated by microbiological testing. Both cold (22oC) and warm (36oC) drinking water is tested. In cold water after 72 hours the number of bacteria must not exceed 100 in 1 ml of water, and in warm water after 48 hours – 50 in 1 ml.
Escherichia coli – the standard is very strict, it does not allow the presence of these bacteria in drinking water at all (0 microorganisms in 1 ml of water). This is a bacterium that is found in large quantities in feces and does not develop survival forms, so the finding of its presence in water indicates fresh contamination. This allows for relatively quick localization of its origin. The appearance of E. coli may also be a signal for the presence of other pathogenic bacteria, which can cause life-threatening diseases (e.g. meningitis)..

Scale of water hardness in Poland

	Degree of water hardness	[mg CaCO_3/dm³]
1	Very soft water	< 100
2	Soft water	100–200
3	Medium hard water	200–350
4	Hard water	350–550
5	Very hard water	> 550

Based on the Regulation of the Minister of Health of 13 November 2015 on the quality of water intended for human consumption - Sejm.gov.pl

Water treatment stages

Water treatment is necessary to remove contaminants resulting from the deposition of various substances in water pipes or wells. Their types and number depend, among others, on the place of intake, level of groundwater, scale of use of the water supply system. Therefore, there is no single, universal method of treatment; each situation is solved individually, always starting with water testing.

Treatment is a process, consisting of stages, which depend on the water nature and purpose. The treatment process is different for water for drinking and hygienic purposes in the household, for water for heating systems, for laboratories or industry. Once the water has been tested, the treatment method can be selected, or the entire procedure can be commissioned to a specialized company. They will take the water and have it tested, and then select the optimal treatment method. The Regulation of the Minister of Health sets the highest requirements for drinking water and water intended for foodstuffs, and slightly limits the parameters for industrial water.

In most cases, water treatment is carried out in three stages:

Mechanical filtration
De-ionizing and de-manganization
Softenin

The first stage of water treatment is mechanical filtration, which removes contaminants from waterworks and wells, such as stones, sand, suspended solids, etc. Mechanical filtration is important for further stages, because if not performed properly, it can damage both the waterworks and the treatment plant. Mechanical filtration uses lint trap, made of stainless steel or plastic, and synthetic filtering cartridges, although the latter are not suitable at higher water flow rates.

The second stage is de-ironing and de-manganization. Iron removal is carried out in a physical and chemical way. Iron salts that have not dissolved in the water are filtered out, oxidation and ion-exchange binding of molecules takes place. De-ionizing is the oxidation of 2+ iron in the dissolved form to 3+ iron, which is insoluble in water and settles in the de-ionizing filters. The resulting sediment is then filtered out and washed away. Manganese, on the other hand, is removed using special catalysts. Both excess iron and manganese cause corrosion, and even the trace presence of manganese in drinking water can cause health problems.

Finally, in the third stage, the water is softened through ion exchange. Calcium and magnesium ions responsible for carbonate hardness in water are exchanged for sodium ions which have no negative impact on the water’s sedimentation. This solution allows customers to use softened water with all its positive aspects.

Water treatment methods

House builders are faced with a decision: water from the mains or from their own intake? Both solutions have their supporters and opponents. Supporters of wells raise the argument of low cost of obtaining water and lack of fees which in the long run will compensate for high costs of well construction. They also claim that well water has much higher quality parameters than water from a water supply system.

Those who are in favour of connection to the water supply system claim that the water is cleaner and of better quality than the water from wells because the water supply company has to comply with certain quality parameters and they have to be periodically inspected. They also claim that the lack of water charges in case of using their own water intake is illusory as pumping water from a well involves increased electricity consumption.

However, certainly the method of water supply to the house will influence the choice of water treatment method, of course taking into account the test, without which any water treatment installation does not make any sense.

Water disinfection. Disinfection is applied to all drinking water, irrespective of its intended use. Both drinking water and industrial water, or water intended for swimming pools for example, is disinfected using various methods such as:

Chlorination – the most commonly used and the cheapest. Chlorine gas, sodium hypochlorite or calcium hypochlorite is added to the water. Although the water will be disinfected, but its smell is quite unpleasant, so it is often additionally dechlorinated with activated carbon. Much more powerful is chlorine dioxide, which in addition to disinfecting properties, has the ability to break down biofilms that form in water tanks and pipes.
Ozonation – used as a disinfectant mainly in the process of producing drinking water, as it destroys microorganisms while preserving the natural taste and smell. This method is also used in the cosmetics and food industry.
UV disinfection – a physical method that involves exposing water to UV light. The process destroys microorganisms and spores, taste and smell remains unchanged, as well as other water parameters. This method is used for drinking water treatment and in industry.
Thermal method – also expensive, as it involves the consumption of energy necessary to heat water to 75°C. Used to combat Legionella, in the food and pharmaceutical industries, and to disinfect hospital and laboratory wastewater. Highly effective, regardless of water quantity and quality.

De-ironing and de-manganization. Neither iron nor manganese are dangerous to humans, but they significantly alter the taste and smell of water, contaminate sanitary equipment with sediment and increase the threat of anaerobic bacteria responsible for corrosion of installations. To put it simply, de-ironing and de-manganization is a two-stage process; first the compounds of both elements are chemically precipitated, and then filtered out.

Demineralization. This is the elimination of any dissolved salts from the water. One of the most effective methods of demineralization is reverse osmosis. Its most important advantage is water treatment without using any chemicals. It retains almost 99% of salts present in water. The resulting water is of high quality. Reverse osmosis treatment is used in gastronomy, hospitals, cosmetic and pharmaceutical industry.

Another method is ion exchange. It has a modular design, which makes the method’s cost not high, while in the case of larger amounts of water, additional panels can be added. This method is mainly used in non-food industry, because the regeneration is done on a chemical basis, using hydrochloric acid or sodium hydroxide.

Water softening. This process involves the removal of substances from the water that cause its hardness (mainly calcium and magnesium compounds). Water softening devices contain ion exchange beds, charged with sodium ions. In the process of ion exchange softening, calcium and magnesium cations are exchanged for sodium cations.

Ion exchange media are subject to regeneration. The frequency of regeneration depends on water hardness level and amount of its consumption. These are also the main criteria on the basis of which water softener is selected. Soft water does not cause scale formation in household appliances, eliminates the need to use large amounts of detergents and definitely improves the taste of food.

Summary

Water is the main component of the human body and is essential for its proper functioning. For this reason, it is important not to put your health at risk due to water contamination. Water treatment is a solution that will provide clean, drinkable water and non-food purposes.

Installation of a water treatment unit does involve an investment, but in the long run it is extremely cost effective. The aforementioned water softener alone will significantly reduce the use of cleaning products and lower energy bills. Skin and hair regain their healthy look and condition, and clothes after washing have intense colors. Treated water is free of herbicides, pesticides and microorganisms. The treatment process also removes chlorine. The water is healthier, tastier and suitable for everyone, including young children, sick people and convalescents.

Therefore, the benefits of water treatment cannot be overestimated for everyone. It provides better health, real savings and is environmentally friendly.