how do public water treatment plants work

How do Water Treatment Plants Work?

1. Collection The first step is to obtain a sufficient volume of untreated water. The source of this raw material varies...
2. Pre-Sedimentation If the filtered water is cloudy, pipes divert it to pre-sedimentation basins. Spending time here...
3. Coagulation Even if the water appears relatively clear and free from large pieces of...
4. Disinfection

Full Answer

What are the steps of a water treatment plant?

What are the steps in water treatment plant?

1. Screening. …
2. Aeration. …
3. Coagulation and flocculation. …
4. Sedimentation. …
5. Filtration. …
6. Chlorination. …
7. Supplementary treatment.

How is the water treated in a water treatment plant?

• Makeup water intake. As water circulates through a cooling tower system, a portion is lost to evaporation, bleed to drain, and leaks. ...
• Filtration. Upon intake, the stream is typically filtered through one or more filtration units for removal of sediment, turbidity, and organic material. ...
• Softening. ...
• Chemical addition. ...
• Side-stream filtration. ...
• Post-treatment. ...

How does a sewage treatment plant actually work?

You’re basically:

• growing the organisms in a suspension and retaining them
• mixing the wastewater with the biomass
• aerating this “mixed liquor” so the bacteria can get to work
• settling out the mixed liquor suspended solids (MLSS)
• sending return activated sludge (RAS) to the reactor basin
• sending waste activated sludge (WAS) to be dewatered and treated accordingly

What are the 5 stages of water treatment?

Water Treatment Process: Follow Water Through a Surface Water Treatment Plant

• Coagulation. ...
• Flocculation. ...
• Sedimentation (or Clarification) The water continues on to the sedimentation basin, or clarifier, after the flocs have been formed. ...
• Filtration. ...
• Disinfection. ...
• Chlorination Operations. ...
• Conclusion. ...

How do water treatment plants work?

4:4010:03How Do Wastewater Treatment Plants Work? - YouTubeYouTubeStart of suggested clipEnd of suggested clipInjected from the bubblers creates an environment. Perfect for the process of aerobic digestionMoreInjected from the bubblers creates an environment. Perfect for the process of aerobic digestion summarized. Simply it's the breakdown of organic matter along with the use of excess oxygen.

What are the steps of a water treatment plant?

Figure 5.2 The seven steps often used in the large-scale treatment of water.1 Screening. ... 2 Aeration. ... 3 Coagulation and flocculation. ... 4 Sedimentation. ... 5 Filtration. ... 6 Chlorination. ... 7 Supplementary treatment.

Where do water treatment plants get their water?

Raw (untreated) water is withdrawn from either a surface water supply (such as a lake or stream) or from an underground aquifer (by means of wells). The water either flows or is pumped to a central treatment facility. Large municipalities may utilize more than one source and may have more than one treatment facility.

How a water treatment plant works for potable water?

The raw water is delivered to the headworks of the water treatment plant where the first of 5 major unit water treatment processes start the treatment to make the water safe to drink. The 5 major unit processes include chemical coagulation, flocculation, sedimentation, filtration, and disinfection (described below).

What are the common steps in treating water for a public water system?

1.) Screening. Surface water (water from Angat Dam and Ipo Dam) often contains large debris, such as sticks, logs, leaves, fish, and trash. ... 2.) Pre-Chlorination (Disinfection) ... 3.) Rapid Mixing. ... 4.) Flocculation. ... 5.) Coagulation. ... 6.) Sedimentation. ... 7.) Filtration. ... 8.) Disinfection.More items...•

What are the 4 main steps to water treatment?

4 Steps of Community Water TreatmentCoagulation and Flocculation. ... Sedimentation. ... Filtration. ... Disinfection.

How does a treatment plant work?

Using internal mechanisms, a sewage treatment plant works by breaking down solid waste to produce a cleaner, more environmentally friendly effluent. Wastewater and sewage are supplied to the primary tank, where the solids and liquids disperse. The resulting liquor flows into the biozone chamber.

Where does the water come from to the treatment plant for waste water?

Wastewater Treatment Plant: Out Water has made its way from a house or place of business through a series of pipes and sewer lines all the way to a wastewater treatment plant. Once here, water is treated by removing solid waste and using bacteria to eliminate the harmful organic matter.

What are the 5 steps of wastewater treatment?

Treatment StepsStep 1: Screening and Pumping. ... Step 2: Grit Removal. ... Step 3: Primary Settling. ... Step 4: Aeration / Activated Sludge. ... Step 5: Secondary Settling. ... Step 8: Oxygen Uptake. ... Sludge Treatment.

What are the 7 steps in wastewater treatment?

The Wastewater Treatment ProcessStage One — Bar Screening. ... Stage Two — Screening. ... Stage Three — Primary Clarifier. ... Stage Four — Aeration. ... Stage Five — Secondary Clarifier. ... Stage Six — Chlorination (Disinfection) ... Stage Seven — Water Analysis & Testing. ... Stage Eight — Effluent Disposal.

What are the 7 methods of water treatment?

Top 7 Methods of Water TreatmentCoagulation / Flocculation. Coagulation is adding liquid aluminum sulfate or alum and/or polymer to raw or untreated water. ... Sedimentation. When water and flocs undergo the treatment process, they go into sedimentation basins. ... Filtration. ... Disinfection. ... Sludge Drying. ... Fluoridation. ... pH Correction.

What are the 3 types of water treatment plant?

Types of Water Treatment PlantsWastewater Treatment Plant (WWTP) ... Sewage Treatment Plants (STPs) ... Effluent Treatment Plants (ETP's) ... Demineralization (DM) Treatment Plants. ... Reverse Osmosis (RO) Water Treatment.

3. Coagulation

Even if the water appears relatively clear and free from large pieces of organic material, looking at a drop under a microscope would probably reveal a world of floating particles and microorganisms. To remove the tiny floaters and swimmers, technicians add chemicals such as aluminum and iron compounds that make them coagulate into small clumps.

4. Flocculation

Flocculation is similar to coagulation but with more dramatic results. In this step, turbines or paddles stir the water for 20 to 30 minutes to increase the frequency with which the smaller pieces bump into each other. This slow agitation causes clumped particles to form larger pieces called flocs.

5. Sedimentation

The flocculated water then rests in a sedimentation basin for 2 to 4 hours. During this time, the flocs gradually sink to the bottom, leaving behind water free from particulate matter. To ensure the sedimentation process removed all impurities, the product flows through a deep layer of sand or anthracite on its way to the final step.

6. Disinfection

The deadliest pathogens in drinking water are invisible to the naked eye. For this reason, the final step is to kill any microorganisms remaining in the otherwise clean drinking water by the addition of disinfectant chemicals. Chlorine is a common substance many plants use, but some also use ozone, chlorine dioxide, or chloramines.

What are the resources used in water treatment?

The local water treatment plants usually rely on natural resources for procuring water, however; that is not always the case. The resources include river, dam, and well. The water that is obtained from these sources is treated thus making it safe for humans to consume at a mass level.

How are coagulants introduced into water?

These coagulants are introduced in the water when it enters the treatment plant. The water is then passed through flocculation basins where slow mixing takes place. This mixing makes sure that thorough coagulation takes place. Once coagulation is completed, the water is pumped into a sedimentation basin. Water is allowed to sit thus enabling the ...

What is a coagulant in water?

This particular process is responsible for removing all of the natural particles that accompany water from the actual water source. Coagulants, when added to the water, can make the debris stick together. An example of a typical coagulant is aluminum sulfites that possess a charge opposite to that of the suspended solids.

How does water pass through a carbon filter?

Once the water reaches the filtration phase, it is made to pass through differing coarseness of sand. Particles keep on getting trapped as the coarseness of the sand filter decreases. In the end, the water is made to pass through an active carbon filter. Once the filtration is over, the water is disinfected. There are three approaches that can be ...

What are the three methods of disinfecting water?

Once the filtration is over, the water is disinfected. There are three approaches that can be employed; chlorination, ozone treatment, and ultraviolet treatment . These approaches can be used either individually or in combination. Once all of these steps are completed, water is pumped out to be used by the population.

Does filtration remove bacteria?

However, filtration helps remove the bacteria as well. Most of the water treatment plants make use of a sand filter. The sand filter is low-tech but is a very efficient way of carrying out water purification. Once the water reaches the filtration phase, it is made to pass through differing coarseness of sand.

How is wastewater drained to the WWTP?

1. Firstly, wastewater is drained to the WWTP by gravity through the main sewer system of the size of a car. Having such size, objects you could hardly imagine reach the WWTPs, ranging from mattresses, fridges, tree branches to wallets disposed of by thieves in order to get rid of the evidence. 2.

What is the first stage of wastewater treatment?

The first mechanical stage is called preliminary treatment or rather pre-treatment. Water flows through gravel chamber for settling out the grit from water. Afterwards, gravel is disposed of at the dump. Water further reaches the bar screens used to remove large objects from the wastewater.

How long does it take for sludge to dry out?

9. Sludge, digested and dewatered to the optimal degree, is finally disposed of at the dump. In about a month, sludge is adequately dried out and ripe. If it complies with agricultural standards, it can be reused for fertilisation of industrial crops.

What is wastewater water?

Wastewater can be divided into two major groups: Sewage water is all wastewater used in domestic dwellings (e. g. originating from toilets, showers or sinks). Industrial wastewater originates from production, industrial and commercial activities, and has a different chemical composition to sewage water.

What is wastewater in agriculture?

What is wastewater? It is used water originating from domestic, industrial, agricultural, and medical or transport activities. Used water becomes wastewater upon the change of its quality, composition and/or temperature. However, wastewater does not include water released from ponds or reservoirs for fish farming.

What is the purpose of bar screens in wastewater treatment?

Water further reaches the bar screens used to remove large objects from the wastewater. At first come the coarse screens and then the fine screens which remove smaller objects such as matches, cigarette butts or undigested foods. 3. After the removal of large objects, grit is to be removed from the wastewater.

What is secondary treatment?

The secondary treatment, also called biological stage, is based on natural processes. WWTPs use bacteria which consume the contaminants, in particular biodegradable organics, carbon and phosphorus. Dead bacteria and organic residues subsequently transform into sludge. 6.

How many processes are there in municipal water treatment?

There are five processes in the primary phase of municipal water treatment. Pumping of water from its source to the municipal treatment plant needs to be done with the appropriate equipment in a way that does not contaminate the supply.

What is the process of treating water with calcium carbonate?

In hard-water areas, water is treated with sodium carbonate to precipitate calcium carbonate, a process known as pre-conditioning. Finally, this primary treatment phase ends with pre-chlorination where water coming into the plant is chlorinated as part of the disinfection process.

How does flocculation work?

Coagulation and flocculation work by clumping particles and solids together by introducing chemicals like aluminum sulfate or iron that cause all contaminants to give off a positive charge . Coagulated particles are easier to filter out through settling water treatment or by sticking to sand or rock.

What is tertiary disinfection?

Tertiary Treatment. Water treatment disinfection is the last stage in the treatment of municipal water and is vital for the removal of pathogens. Most municipal water systems have a requirement to maintain a level of disinfection in the supply for a certain number of days before it reaches the consumer. Wastewater chlorination is the most common ...

What is secondary treatment?

Secondary Treatment. Several techniques can be used to filter and dissolve solids during the secondary treatment phase. The municipal water treatment methods used will depend on whether this is a hard-water area, cost, and any quality requirements that need to be in place.

What is pH adjustment?

pH adjustment is applied where the water supply is acidic. In this situation lime or soda ash is added to raise the pH level. When water is slightly alkaline it enables flocculation and coagulation to work more effectively during the municipal water treatment process.

What is the difference between primary and secondary treatment?

The main difference between the primary and secondary treatment of wastewater is that primary relies mostly on physical cleaning, while secondary treatment introduces chemical procedures and microorganisms. In the final stage, or tertiary treatment, at the municipal water plant, pH adjustment, disinfection, and carbon treatments are applied.

What is NTNCWS water?

Non-transient non-community water systems (NTNCWS) regularly supply water to at least 25 of the same people at least six month per year, but not year-round (for example, schools, factories, office buildings, and hospitals which have their own water systems). The EPA is responsible for the nation’s drinking water regulation.

How long does a non-community water system last?

Transient non-community water systems (TNCWS) provide water to 25 or more people for at least 60 days/year, but not to the same people and not on a regular basis (for example, gas stations, campgrounds). Non-transient non-community water systems (NTNCWS) regularly supply water to at least 25 of the same people at least six month per year, ...

How many people does a non-community water system serve?

It serves at least 25 people at their primary residences or at least 15 residences that are primary residences (for example, municipalities, mobile home park, sub-divisions). Non-community water systems are composed of transient and non-transient water systems.

How is wastewater drained?

Waste water is drained through pipe systems and thus enters the public sewerage system . Here we differentiate between two types of drainage. In the combined sewer system, domestic and commercial wastewater is fed into a sewer together with rainwater that accumulates on sealed surfaces (e.g. streets and roofs).

What is the process of removing nutrient from wastewater?

In the actual clarifier, bacteria and fungi have the task of metabolising organic components in the wastewater into its individual parts. This process is called Biological nutrient removal. Oxygen-rich and oxygen-poor areas provide optimal conditions for breaking down all carbon and phosphate compounds and urea from the urine.

How does a separate sewer system work?

The separate sewer system divides the media. Dirty water is fed into one sewer, surface water into another. Because of the low dirt load, the collected surface water is usually discharged into neighbouring waters (lakes or rivers). The wastewater and the combined sewer both end up at the treatment plant. Of course, in the case of combined sewer ...

What is the process of cleaning a toilet called?

Rakes filter everything that is not permeable as solid matter in the wastewater. This can be toilet paper, wet wipes, but also a toothbrush or other things that do not belong in a toilet. This process is called pretreatment.

Where does wastewater end up in a combined sewer system?

The wastewater and the combined sewer both end up at the treatment plant. Of course, in the case of combined sewer systems, the sewage treatment plant has more work to do, as all the surface water has to be cleaned as well.

What happens to clarified water?

In the end, the clarified water is returned to the natural water cycle, usually lakes or streams. Very modern sewage treatment plants have additional treatment stages for further phosphorus elimination or the killing of pathogens.

How much water does a person use?

Each person uses an average of 120 litres of water per day. This is used for a wide variety of purposes (body cleansing, cooking, flushing toilets, etc.).

Pre-Sedimentation

See more on cdc.gov

Coagulation

Flocculation

Sedimentation

Disinfection