The water treatment process includes many operations like screening, aeration and sedimentation, sedimentation with coagulation, softening, filtration, disinfection, etc. The water treatment process generally adopted depends upon the quality of raw water and the quality of water derived. Methods of the water treatment process are explained below.
- Coagulation. Coagulation is often the first step in water treatment. ...
- Flocculation. Flocculation follows the coagulation step. ...
- Sedimentation. Sedimentation is one of the steps water treatment plants use to separate out solids from the water. ...
- Filtration. ...
- Disinfection.
What are the objectives of the water treatment process?
Some of the main objectives of the water treatment process are: 1. To reduce the impurities to a certain level that does not cause harm to human health. 2. To reduce the objectionable colour, odour, turbidity and hardness.
What are the physical and chemical processes involved in wastewater treatment?
Physical processes for mechanical preparation such as aeration, sedimentation or thermal influence. This also includes the use of screens, filters and sieves. Biological processes such as anaerobic wastewater treatment, biochemical oxidation or sludge digestion Chemical processes such as neutralisation, disinfection, flocculation and precipitation
How does a water treatment plant work?
As water enters a water treatment plant, either from lakes, rivers, or the ground, it passes through a screening. This screening keeps large natural contaminants out of the water.
Why do we need water treatment?
With the ever increasing rise in pollution levels in today's world there is an urgent need for water treatment techniques through which the contaminated water can be purified and treated of its pollutants & waste and used or safely returned to the environment.
What are the basic processes involved in water treatment?
The 5 major unit processes include chemical coagulation, flocculation, sedimentation, filtration, and disinfection (described below). There are chemicals added to the water as it enters the various treatment processes.
How does the process of water treatment work?
There are two basic stages in the treat- ment of wastes, primary and secondary, which are outlined here. In the primary stage, solids are allowed to settle and removed from wastewater. The secondary stage uses biological processes to further purify wastewater. Sometimes, these stages are combined into one operation.
What are the 3 steps of water treatment?
There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment.
What are the 4 stages of wastewater treatment?
Four common ways to treat wastewater include physical water treatment, biological water treatment, chemical treatment, and sludge treatment. Let us learn about these processes in detail. In this stage, physical methods are used for cleaning the wastewater.
What are the 6 steps of drinking water treatment?
They typically consist of several steps in the treatment process. These include: (1) Collection ; (2) Screening and Straining ; (3) Chemical Addition ; (4) Coagulation and Flocculation ; (5) Sedimentation and Clarification ; (6) Filtration ; (7) Disinfection ; (8) Storage ; (9) and finally Distribution.
What are the three stages in the treatment of water give the objectives of each stage?
The three stages of wastewater treatment are known as primary, secondary and tertiary. Each stage purifies water to a higher level. In some applications, only one or two stages are necessary. The level of treatment necessary depends on the water's intended use case, and what environment it will be discharged into.
What is the first stage of water treatment?
Purifying water Sedimentation – the water is stored in a large tank or a reservoir. This slows down the flow of the water and allows large, insoluble particles to settle to the bottom. The cleaner water at the top can then be extracted for the next stage.
What are the 3 stages of wastewater treatment PDF?
Wastewater is treated in 3 phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration).
What are the objectives of water treatment?
Some of the main objectives of the water treatment process are: 1. To reduce the impurities to a certain level that does not cause harm to human health. 2. To reduce the objectionable colour, odour, turbidity and hardness. 3. To make water safe for drinking. 4.
What is water treatment?
Water from any source may contain various suspended, colloidal and dissolved impurities which may be harmful or useful for drinking purpose. The process of removal of undesirable matters and pathogens from water is called the water treatment process. The degree of treatment depends upon the quality ...
How long does it take for particles of 0.006 mm to settle in plain sediment?
Particles of sizes 0.006 mm required 10 hours to settled in plain sedimentation. Therefore we need certain chemicals to add in the water to remove such impurities which are not removed by plain sedimentation. These chemical are known as coagulants and the process is called sedimentation with coagulation.
What is sedimentation tank?
The particles whose specific gravity is greater than that of water gets settles down under the action of gravity. Sedimentation tanks are designed to reduce the velocity of flow of water so that the suspended particles get settled under the action of gravity. Sedimentation can be achieved in two ways. 1.
What is the process of removing suspended particles by gravitational settling called?
The process of the removal of suspended particles by gravitational settling is called sedimentation. The water after screening may contain various suspended impurities like silt and clay particles. So to remove such particles sedimentation is done.
What is the most widely used method of water treatment?
Among them; chlorination is the most widely used method. So, we are explaining only chlorination. Chlorination is the process of addition of chlorine to kill the bacteria. Chlorination is widely adopted in all developing countries for the treatment of water in the public water supply system.
What is the process of passing water through a bed of sand?
The process of passing water through beds of sands or gravels is known as filtration. It consists of a bed of sand supported on gravel.
What are the stages of water treatment?
Several processes are at your disposal for implementing the various preparation stages of water treatment: Physical processes for mechanical preparation such as aeration, sedimentation or thermal influence. This also includes the use of screens, filters and sieves. Biological processes such as anaerobic wastewater ...
What are the two types of wastewater treatment?
Firstly, problematic substances are removed from the water. This is done with cleaning, iron removal, manganese removal, sterilisation, desalination or softening .
What is the purpose of return sludge?
The other part of the sludge, also known as "return sludge" is returned to the aeration tank to ensure that there are enough microorganisms in the aeration tank to break down the dirt. After biological treatment, approximately 90% of the wastewater is cleaned of biodegradable substances.
What is the name of the tank that cleans wastewater?
In most wastewater treatment plants, the water pre-purified in the mechanical treatment stage now reaches what are known as aeration tanks, which are often designed as circulation tanks. This is where the biological cleaning takes place.
How much of the wastewater is removed in the first stage?
In the first stage, the still completely untreated wastewater is mechanically treated; this removes about 20 - 30% of the contained solids. To achieve this, the wastewater is guided into a screening plant, where a screen or sieve drum filters out coarse impurities such as leaves, paper or textiles.
Why is water a precious commodity?
Water is a precious commodity. To protect our natural waters and to support drinking water production, all wastewater is therefore first cleansed of containments and pollutants before it is returned to the water cycle. To treat the water and to achieve the best possible, natural water quality, different processes are used.
What is the function of bacteria in water?
The bacteria form activated sludge flocks that float freely in the water . The supply of oxygen stimulates the multiplication of bacteria and thus promotes the formation of activated sludge.
What is water treatment?
Water treatment means the cleansing of water through various phases to be available for end-use by the people. The treated water is then used for various purposes like irrigation, industrial water supply, drinking, river flow maintenance, or any other such uses. The treatment of water removes harmful contaminants and compounds or the concentration of these is reduced for public use. This treatment is mandatory to promote human health and its uses for drinking and irrigation.
Why is water treatment important?
The availability of pure water is of utmost importance in society. The water treatment process caters to this by supplying suitable water for industries or individuals. Only when the contaminants are removed from the water can they be used and accessible to everyone. Several processes like filtration and disinfection are used to purify water.
What is treated raw water?
Raw water must be treated before use in utility processes. The treatment removes harmful substances like suspended and dissolved solids and other kinds of impurities that are present in large numbers. Treated raw water can be used for various purposes like cooling water, rinsing water, purified, and even drinking water. The process of raw water treatment includes:
What is the chemical used to disinfect water after sedimentation?
To further disinfect the water after sedimentation a chemical called chlorine is used to help remove pathogenic microorganisms. The remaining chlorine is known as residual chlorine which gets through the process of the distribution system.
What is filtration in water?
These filters are composed of sand and gravel or crushed anthracite. Filtration combines all the dangerous impurities and particles that float on the water. This helps boost the effectiveness of disinfection. Filters are regularly serviced by backwashing for better filtration.
Why is fluoride used in water?
Fluoridation is used mainly in communities as it treats water supplies to bring a balance in the concentrated free fluoride ions. This is done till an optimal level is reached which helps avoid dental cavities.
What is the process of adding alum, liquid sulfate, to untreated or raw water?
Coagulation is the process of adding alum, liquid sulfate, to untreated or raw water. After completion of the process, dirt particles coagulate in the water or stick together. Flocs are formed by large dirt particles and can be easily removed by filtration or setting. Coagulation methods include ionic layer compressions, surface complexation, and charge neutralization, sweep coagulation , and polymeric bridging.
What is water treatment?
Water treatment is the process of removing all those substances, whether biological, chemical, or physical, that are potentially harmful to the water supply for human and domestic use. This treatment helps to produce water that is safe, palatable, clear, colorless, and odorless. Water also needs to be non-corrosive, meaning it will not cause damage to pipework.
How does aerated water work?
After screening, the water is aerated (supplied with air) by passing it over a series of steps to take in oxygen from the air. This process helps in expelling soluble gases such as carbon dioxide and hydrogen sulfide (both of which are acidic, so this process makes the water less corrosive) and expels any gas eous organic compounds an undesirable taste to the water. Aeration also removes iron or manganese by oxidation of these substances to their insoluble form. Iron and manganese can cause peculiar tastes and can stain clothing. Once in their insoluble forms, these substances can be removed by filtration.
What is the process of separating solids from liquids?
Filtration is the process where solids are separated from a liquid. In water treatment, the solids that are not separated in the sedimentation tank are removed by passing the water through sand and gravel beds. With a flow rate of 4–8 cubic meters per square meter of filter surface per hour, rapid gravity filters are often used.
What happens after aeration?
After aeration, coagulation occurs to remove the fine particles (less than 1 µm in size) suspended in the water . In this process, a chemical called a coagulant (with a positive electrical charge) is added to the water, which neutralizes the fine particles' negative electrical charge. The coagulant's addition takes place in a rapid mix tank where a high-speed impeller rapidly disperses the coagulant.
What do water treatment plants use?
Water treatment plant operators typically do the following: Add chemicals, such as ammonia, chlorine, or lime, to disinfect water or other liquids. Inspect equipment on a regular basis. Monitor operating conditions, meters, and gauges. Collect and test water and sewage samples.
How to operate a water treatment plant?
Water treatment plant operators typically do the following: 1 Add chemicals, such as ammonia, chlorine, or lime, to disinfect water or other liquids 2 Inspect equipment on a regular basis 3 Monitor operating conditions, meters, and gauges 4 Collect and test water and sewage samples 5 Record meter and gauge readings, and operational data 6 Operate equipment to purify and clarify water, or to process or dispose of sewage 7 Clean and maintain equipment, tanks, filter beds, and other work areas 8 Stay current on environmental laws and regulations 9 Ensure safety standards are met
What is wastewater operator?
Operators are trained in emergency management procedures and use safety equipment to protect their health, as well as that of the public. Wastewater treatment plant and system operators do similar work to remove pollutants from domestic and industrial waste. Used water, also known as wastewater, travels through sewage pipes to treatment plants ...
What causes large amounts of storm water to flow into sewers?
For example, weather conditions may cause large amounts of storm water or wastewater to flow into sewers, exceeding a plant’s capacity. Emergencies also may be caused by malfunctions within a plant, such as chemical leaks or oxygen deficiencies.
What do sewage workers do?
Many others work for water, sewage, and other systems utilities and for waste treatment and disposal services. They work both indoors and outdoors. They may be exposed to noise from machinery and are often exposed to unpleasant odours.
Where does used water go?
Used water, also known as wastewater, travels through sewage pipes to treatment plants where it is treated and either returned to streams, rivers, and oceans, or used for irrigation. Are you suited to be a water treatment plant operator? Water treatment plant operators have distinct personalities. They tend to be realistic individuals, which means ...
How many hours a day do plant operators work?
Plants operate 24 hours a day, seven days a week. In small plants, operators are likely to work during the day and be on call nights and weekends. In medium and large sized plants that require constant monitoring, operators work in shifts to control the plant at all hours.
Why do water treatment systems fail?
Many water treatment and supply systems fail because of a lack of spare parts. Managers should be proactive and order adequate quantities of the parts that fail frequently. Doing this has the benefit of allowing repairs to be undertaken immediately, instead of time being spent going to the market to search for the appropriate part.
What department manages the water supply?
The Finance Department manages the water utility’s budget and makes sure that all financial transactions are recorded, and that revenue is collected for water supplied. Finally, if relevant, the Sewerage Department looks after the sewer network and sewage treatment.
What will happen if water is not available?
If clean water is also not available, the health of people will be at serious risk. Utilities must therefore plan and be prepared for such eventualities.
What are the two types of maintenance?
There are two types of maintenance: Corrective or breakdown maintenance: this is carried out when components fail and stop working. Breakdown is common in many utilities in Ethiopia and occurs as a result of poor preventive maintenance (explained next).
What is the purpose of operation and maintenance?
Operation and maintenance of a water supply system refers to all the activities needed to run the system continuously to provide the necessary service . The two words are very frequently used together and the abbreviation ‘O&M’ is widely used. The overall aim of operation and maintenance is to ensure an efficient, effective and sustainable system (Castro et al., 2009). ‘Efficient’means being able to accomplish something with the least waste of time, effort and resources; ‘effective’ means being successful in producing the intended result; and ‘sustainable’ means able to be maintained at the best level over time – in this case, the supply of water.
What is the planning department?
The Planning Department plans for the growth in services provided. The Commercial and Customer Care Department handles queries and complaints from commercial and domestic customers. The Engineering Department is responsible for major engineering works, such as refurbishment or expansion of facilities.
What is a town water board?
The Town Water Board is a committee made up of individuals who are specialists in water treatment and supply, representatives of other sector offices such as Health and Education, and other stakeholders (in this context, representatives of people who would be affected by the water utility’s actions).
Coagulation
Flocculation
- Following the coagulant chemical addition and the rapid mix processes, the raw water will continue on to a flocculation basin. The goal of the flocculation treatment process is to increase the size of the flocs in order to increase their ability to settle out.
Sedimentation
- The water continues on to the sedimentationbasin, or clarifier, after the flocs have been formed. The goal of this stage of the treatment process is to reduce the amount of solids in the water before the water is filtered in the next treatment step. The large flocs will settle out of suspension via gravity. Clarifiers can remove a very large percentage of the suspended materials in water. I…
Filtration
- The final water treatment process in removing particulates is filtration. The sedimentation process will have already removed a large percentage of the suspended solids. Sedimentation is unable to remove many small particles in water though. Filtration will remove these microorganisms and other suspended material that did not settle out previously.
Disinfection
- As discussed previously, the surface water treatment rule requires both the filtration and disinfection of surface water sources. The water must be disinfected now that it has been filtered.
Chlorination Operations
- Chlorination was one of the first drinking water disinfection methods. It is still the most commonly used disinfection method used today. The filtered water is injected with either liquid sodium hypochlorite, gaseous chlorine, or solid calcium hypochlorite. Chlorine is a strong oxidant. It is used to both disinfect and also to remove color, taste and odor compounds, iron and manganes…
Conclusion
- In order to meet the requirements of the Surface Water Treatment Rule, a water system must both remove and inactivate the pathogens in the water. This process begins with coagulation, which destabilizes the particles in the water. Then, during flocculation, the destabilized particles bump into each other and form larger and larger flocs. These large flocs are given adequate time to se…
I. Introduction
II. Objectives of The Water Treatment Process
- Some of the main objectives of the water treatment process are: 1. To reduce the impurities to a certain level that does not cause harm to human health. 2. To reduce the objectionable colour, odour, turbidity and hardness. 3. To make water safe for drinking. 4. To eliminate the corrosive nature of water affecting the pipe. 5. To make it suitable for a wide variety of industrial purpose…
III. Methods of The Water Treatment Process
- The water treatment process includes many operations like screening, aeration and sedimentation, sedimentation with coagulation, softening, filtration, disinfection, etc. The water treatment process generally adopted depends upon the quality of raw water and the quality of water derived. Methods of the water treatment process are explained below.
IV. The Layout of The Water Treatment Plant
- Following are the major consideration for the layout of a treatment plant: 1. The water treatment plant should be located near the distribution area to reduce the contamination in distribution. 2. All the units are arranged in a way that a minimum area is required to reduce the cost of construction. 3. All the units of plants should be located in an order of sequence flow from one u…
Water Treatment
- Water treatment means the cleansing of water through various phases to be available for end-use by the people. The treated water is then used for various purposes like irrigation, industrial water supply, drinking, river flow maintenance, or any other such uses. The treatment of water removes harmful contaminants and compounds or the concentration ...
Methods of Water Treatment
- Water is naturally a pure substance containing hydrogen and oxygen. However, the distribution and supply of water come in contact with various organic minerals, man made pollutants, and chemicals. This makes water unfavorable for drinking purposes as it contains deadly viruses, bacteria, and other dangerous agents. Different methods of water treatment are set up to make …
Steps of Water Treatment
- Large scale water treatment plant follows the below steps for urban water supply. These are as follows: –
Importance of Water Treatment
- The availability of pure water is of utmost importance in society. The water treatment process caters to this by supplying suitable water for industries or individuals. Only when the contaminants are removed from the water can they be used and accessible to everyone. Several processes like filtration and disinfection are used to purify water. Water is the key element to an …
Purposes of Water Treatment
- Water treatment’s main objective is to remove the impure residuals of the water to make it accessible for drinking. These impurities are responsible for various types of diseases among humans. The main purpose of water treatment is to ensure the public has safe access to drinking water devoid of any contaminants. At the community level, untreated or raw water is obtained th…
Raw Water Treatment
- Raw water must be treated before use in utility processes. The treatment removes harmful substances like suspended and dissolved solids and other kinds of impurities that are present in large numbers. Treated raw water can be used for various purposes like cooling water, rinsing water, purified, and even drinking water. The process of raw water treatment includes: 1. Revers…
Types of Water Treatment Plants
- On the basis of the types of water industries, they can be divided into 3 major categories. 1. Water purification 2. Wastewater treatment 3. Desalination 4. Water purification:Natural water may not contain harmful elements still the water is sent for purification in order to become drinkable. Natural and purified water has a similar appearance but is different in taste and smell as there a…