Introduction

Water filtration plants are used to filter water that is supplied to communities with a view of providing safe water that does not contain any form of contaminated water such as polluted water. They all employ a range of advanced equipment and procedures in water treatment in an attempt to overcome numerous source that provide pollution and contaminants in water. In this article, the author analyses the process of treatment of contaminants and pollutants in water filtration plants, major procedures and technologies implemented to improve the standard of water safety and quality (AWWA, 2018).

Understanding Contaminants and Pollutants

Since contamination and pollution are inevitable, the best way to deal with them is by controlling them meaning that one needs to know what they are, where they come from and how to prevent them from becoming a menace to the environment. Water contains different types of contaminants that can be classified in the physical, chemical, biological type. Physical contaminants include suspended particulate matter for instance sand, silt and organic materials. Chemical pollutants include heavy metals, pesticides, chemical and industrial products. Biological risks are microorganisms including bacteria, viruses, and protozoa that have an effect on biological health.

Water pollutants can be from point sources such as industrial effluents, agricultural drainage, sewage and nonpoint sources such as precipitation. Knowledge of the particular contaminants and their origins enables the water filtration plants to structurally develop efficient methods of purification of water. Many water filtration plants use several steps of purification in order to get rid of these substances and make the water potable (EPA, 2020).

The Role of Coagulation and Flocculation

In water filtration plants, the first processes that are normally adopted are coagulation and flocculation. These processes are aimed at reducing the pollutants from the water to their physical and some chemical aspects. Coagulation entails the use of substances referred to as coagulants which are incorporated to the water. These chemicals for instance alum or ferric chloride destabilizes the charges on suspended particles in turn forcing them to combine and form bigger masses referred to as flocks.

After coagulation, the water is subjected to flocculation in which quiet mixing is done to enhance the growth of flocks, which can be easily eliminated. As a result of coagulation and flocculation, a considerable amount of flock is formed which can be easily separated through sedimentation. It is the last step of an initial level of treatment that is in a position to successfully filter out large particles and the majority of colloidal contaminants (WHO, 2021).

Sedimentation and Clarification

Sedimentation is one of the water filtration processes which precedes sedimentation after the processes of coagulation and flocculation. Sedimentation: water is let to settle in big tanks known as sedimentation basins or clarifiers, where gravity assist to pull apart the flocculated particles from clear water. The heavier flocks settle to the bottom of the tank and form layers of sludge that is occasionally being discharged. The water here is visibly clear and free from a large amount of suspended solids, which then percolate to the next stage of treatment.

Another very similar process to clarification is purification which adds to the removal of residual particles and contaminants. In some plants it is followed by an additional chemical treatment to enhance the water quality that is its clarity. Sedimentation and clarification efficiencies are influenced by such concepts as tanking characteristic, flow rates and types of particles which have been flocked. It is important to note that operation and maintenance of these processes if properly carried out leads to production of high quality treated water (Foundation, 2022).

Filtration Technologies

Following sedimentation and clarification processes there is normally filtration of the water in order to remove any remaining suspended particles and other smaller forms of pollutants. There are some filtration technologies that are used depending with the requirements of the water filtration plant. In sand filters the water is passed through a sand bed which helps to filter out the suspended impurities. The water first passes through the sand bed and as it does so the particles are sieved by the sand grains. Sand filtration is useful for pulling out rather big particles and the technique can sometimes need backwashing (Sciences, 2019).

Granular or powdered activated carbon filters for removal of organic compounds including pesticides and volatile organic compounds (VOCs) and some chemicals. Due to high surface area of the activated carbon it has the ability to adsorb and remove large no of organic pollutant. Micro filtration, ultra filtration, Nano filtration and reverse osmosis which are part of membrane technologies involves the use of a membrane- a semi permeable barrier that segregates contaminants from water. These methods are very efficient for the removal of a wide range of impurities that can be present in the water such as microorganisms, dissolved salts and small organic molecules. Pressure filtration systems involves passing water through filter media under pressure which increases the filtration efficiency on the particulate and contaminants. This method is normally applied to complement other filtration technologies in a bid to improve on the level of purification of the water (IWA, 2021).

Disinfection and Chemical Treatment

Once filtration of the water is done, the water gets disinfected in a move aimed at eradication of any remaining living microorganisms. Disinfection is one of the effective measures that should be taken to ensure that the disease does not spread by drinking water. Common disinfection methods include:

Chlorine is used extensively for water treatment because it is known to kill bacteria, viruses and all pathogenic species. Chlorine exists in different forms and it can be in the form of gas, liquid or solid. It also offers post-sediment barriers to control and preserve the water safety in the distribution process. Ultraviolet (UV) Light UV disinfection can be defined as the use of ultraviolet light to kill water-borne microorganisms, since the ultraviolet light affects the DNA of such microorganisms. UV treatment is very efficient in eliminating most of the pathogens in water without adding any form of chemical in the water (Engineering, 2020).

Ozone is a strong oxidizer that can be used for the disinfection processes and also used to eliminate all the organic and inorganic pollutants. Zonation has the ability to neutralize microorganisms and cause breakdown of some chemicals hence enhancing water quality. Advanced Oxidation Processes AOPs are used to have ozone, hydrogen peroxide and UV light to produce hydroxyl radicals that can decompose anything different that is in water. This advanced method is effective in treating water with a number of problems in their contamination.

Addressing Chemical Contaminants

Water filtration plants also have to pay attention to chemical substances which could possibly be existing in the water supply. Such contaminants include heavy metals, industrial chemicals and pesticides which are very dangerous for human health in case they are not well handled. Various treatment methods are employed to address chemical contaminants: Various treatment methods are employed to address chemical contaminants (WEF, 2021).

Ion Exchange

Ion exchange resins are effective for the removal of some ions from the water whose presence is undesirable for one reason or the other including the heavy metals and radionuclides. Here ion forms in the water are exchanged by ion forms present in the resin which in turn purifies the water on the treatment process.

Chemical precipitation involves adding chemicals to the water which creates a chemical reaction between the micro-pollutants with other chemicals that can from a solid which can be settled or filtered out. This method is widely applied for the extraction of soluble inorganic pollutants including the heavy metals. Adsorption processes employ substances including activated carbon, or alumina to selectively retain contaminants and purify water. Adsorption is widely used for decontamination of the water containing organic chemicals such as solvents, pesticides and some heavy metals (ASCE, 2020).

Managing Residuals and Waste

The treatment processes involved with the water filtration plants produce residuals and waste materials which have to be disposed of in an efficient manner. Such residuals may comprise of the sludge gotten through sedimentation, spent filter media and spent chemicals. There is therefore the need to manage and dispose of such materials in a way that would enhance proper working conditions as well as environmental conditions.

Sedimentation and filtration produce sludge which has to be treated and disposed depending on the pertinent laws and regulations. Some of the practices applied in sludge management comprise dewatering, stabilization and disposal either in a landfill or by incineration. There will also be instances when some plants may try to find ways in using sludge again for its recycle or reformulation in order to reduce waste and harm to the environment (Intelligence, 2022).

Used filter media and chemicals that are to be discarded also should be disposed properly so as to avoid polluting the environment. Some filter media might be reused while others might be retired or regenerated depending on the type of filter in question and its state. The chemicals that have undergone a particular process have to be discharged after they have undergone through a process that reduces their impact on the environment, such as chlorine or the ozone.

Conclusion

In the water filtration plants the purification procedures and technologies are managed systematically to deal with impurities and pollutants. Starting from coagulation and sedimentation processes and ending with filtration and disinfection these facilities are well aimed at maintaining high quality and safe water supply. Therefore, through an understanding and control of the various ways and places that contamination can occur and through the use of current and effective treatment procedures the water filtration plants play a role in ensuring that public health is not at risk and that the water supplies are protected for future use (AWWA, 2018).

References

ASCE, A. S. (2020). Water and Wastewater Engineering: Design Principles and Practice. McGraw-Hill Education.

AWWA, A. W. (2018). Water Treatment: Principles and Design. McGraw-Hill Education.

Engineering, J. o. (2020). Recent Advances in Water Filtration and Contaminant Removal. Elsevier.

EPA, U. E. (2020). Drinking Water Treatability Database. Retrieved from https://cfpub.epa.gov/safewater/watersupply/treat/index.cfm.

Foundation, W. R. (2022). Advanced Treatment Technologies for Contaminant Removal. Retrieved from https://www.waterrf.org.

Intelligence, G. W. (2022). Innovations in Water Treatment. Retrieved from https://www.globalwaterintelligence.com.

IWA, I. W. (2021). Water Treatment Technologies and Management. Retrieved from https://iwa-network.org.

Sciences, N. A. (2019). Water Treatment and Safe Drinking Water. National Academies Press.

WEF, W. E. (2021). Water Treatment Fundamentals. Retrieved from https://www.wef.org.

WHO, W. H. (2021). Guidelines for Drinking-Water Quality. Retrieved from https://www.who.int/water_sanitation_health/publications/dwq-guidelines/en/.