2. Wastewater treatment processes
| Process | Purpose |
| Screening | To remove suspended and floating materia ... |
| Comminution | To reduce the size of coarse particles |
| Coagulation | To neutralize the charge of suspended an ... |
| Flocculation | To mix the flocculants and wastewater fo ... |
- Step 1: Screening and Pumping. ...
- Step 2: Grit Removal. ...
- Step 3: Primary Settling. ...
- Step 4: Aeration / Activated Sludge. ...
- Step 5: Secondary Settling. ...
- Step 6: Filtration. ...
- Step 7: Disinfection. ...
- Step 8: Oxygen Uptake.
How does wastewater treatment worksthe basics?
What does a wastewater treatment system typically remove?
- Biochemical oxygen demand. Biochemical oxygen demand, or BOD, refers to the amount of dissolved oxygen needed by aerobic biological organisms to break down organic matter into smaller molecules.
- Nitrates and phosphates. ...
- Pathogens. ...
- Metals. ...
- Total suspended solids. ...
- Total dissolved solids. ...
- Synthetic chemicals. ...
What happens to treated wastewater?
What happens to the treated water when it leaves the wastewater treatment plant? The treated wastewater is released into local waterways where it’s used again for any number of purposes, such as supplying drinking water, irrigating crops, and sustaining aquatic life.
What is sewage water and its treatment process?
Process of Treating Wastewater
- Pre-treatment. It is the very first step just before the actual treatment. ...
- Primary Treatment. The wastewater at this point is devoid of solid materials and grit but has dissolved organic and inorganic solids which are treated at this stage.
- Secondary Treatment. In this stage, there are two ways to go about it. ...
- Tertiary Treatment. ...
- Sludge Treatment. ...
How do you treat waste water?
Water & Wastewater Treatment Automation Can Help Protect the Environment
- Safeguarding Nearby Resources. When decision-makers move forward with wastewater treatment automation, numerous factors often drive their choices.
- Meeting Waste Disposal Mandates. ...
- Achieving Real-Time Visibility. ...
- Improving Quality Control. ...
- Water & Wastewater Treatment Automation to Protect the Earth. ...
What are the 4 stages of wastewater treatment?
4-Step Wastewater Sludge Treatment ProcessStep 1 – Sludge Thickening. The first step in the sewage sludge treatment plan is called thickening. ... Step 2 – Sludge Digestion. After amassing all the solids from the sewage sludge begins the sludge digestion process. ... Step 3 – Dewatering. ... Step 4 – Disposal.
What are the 4 main processes of treating water?
Water treatment stepsCoagulation. 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 3 stages of wastewater treatment?
There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water 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 stages of 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 types of wastewater?
Types of sewage There are three types of wastewater, or sewage: domestic sewage, industrial sewage, and storm sewage. Domestic sewage carries used water from houses and apartments; it is also called sanitary sewage.
What are the 3 types of sewage treatment and describe each one?
Wastewater is treated in 3 phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration).
What about industrial waste? Can public wastewater treatment plants really remove all of those toxic chemicals?
Commercial and industrial waste is not sent directly to public wastewater treatment plants, because the public wastewater treatment system cannot effectively remove all of the contaminants. Wastewater from commercial and industrial processes is usually divided into the following four categories and dealt with accordingly:
Who is Responsible for Making Sure that Wastewater is Treated Properly?
Similar to drinking water provisions, the federal government has delegated responsibility for wastewater treatment to the provinces and territories. There are two federal acts, however, that may apply to wastewater. The Fisheries Act prohibits the release of harmful substances into waters that fish live in. The Canadian Environmental Protection Act governs the release of toxic substances into the environment and allows the federal government to develop regulations for the use of toxic substances.
How do Cities Treat Wastewater, to Make it Safe for Discharge?
There are several levels of wastewater treatment; these are primary, secondary and tertiary levels of treatment. Most municipal wastewater treatment facilities use primary and secondary levels of treatment, and some also use tertiary treatments. The type and order of treatment may vary from one treatment plant to another, but this diagram of the Ottawa-Carleton wastewater treatment plant illustrates the basic components.
How to reduce pressure on septic system?
Following some water conservation practices can greatly reduce pressure on your septic system. For more information about conserving water, see the fact sheet about Water Consumption. Here are a few things that you can do to care for your septic system: 1 Do not use your drain or toilet as a garbage disposal; avoid putting dental floss, diapers, coffee grounds and paper towel down the drain, as they can clog up your septic system. 2 Spread your loads of laundry out over the week. When too much water is added to the septic tank, it does not have time to treat wastes, and you could be flooding your drainfield with wastewater. 3 Plant grass on your drainfield, but keep trees and shrubs away from it, because roots can clog the system and cause damage. 4 Do not drive on your drainfield, because this can compact the soil and damage the septic system components.
Why is oxygen important in wastewater treatment?
The oxygen helps the bacteria to digest the pollutants faster. The water is then taken to settling tanks where the sludge again settles, leaving the water 90 to 95 percent free of pollutants. The picture below shows the settling tanks in the Winnipeg Wastewater Treatment Plant.
How is sludge treated?
The sludge that is removed from the settling tanks and the scum that is skimmed off the top during the primary steps are treated separately from the water. Anaerobic bacteria (anaerobic bacteria do not require oxygen) feed off of the sludge for 10 to 20 days at temperatures around 38 degrees Celsius. This process decreases the odour and organic matter of the sludge, and creates a highly combustible gas of methane and carbon dioxide, which can be used as fuel to heat the treatment plant. Finally, the sludge is sent to a centrifuge, like the one shown in the picture below. A centrifuge is a machine that spins very quickly, forcing the liquid to separate from the solid. The liquid can then be processed with the wastewater and the solid is used as fertilizer on fields.
Why do cities dump raw sewage?
Some cities choose to dump raw sewage into the oceans and rivers, because it is cheaper than effective treatment . A report published by Sierra Legal found that, of 22 Canadian cities, Victoria, Dawson City, Montreal, Saint John, Halifax and St. John’s dump some or all of their raw sewage directly into water bodies. While not all of the sewage is dumped directly into the oceans, these six cities produce 400 million litres of raw sewage each day! Montreal dumps around 3.6 billion litres of raw sewage into the St. Lawrence River each year, and Victoria is the only large Canadian city to dump all of its waste into the ocean without any attempt to improve the system. The city of Victoria dumps more than 34 billion litres of raw sewage into waterways each year, and still claims that their actions are not harming the environment! Halifax and St. John’s have plans to construct wastewater treatment facilities, but in the meantime, are still discharging 65.7 billion litres and 33 billion litres, respectively, of raw sewage into the Atlantic Ocean. For more information about water pollution, see the Water Pollution fact sheet, or the Operation Water Pollution lesson plans and resources.
Importance of Wastewater Treatment Process
Wastewater contains a large number of toxins that might harm the environment; thus, treatment is essential.
Stages of Wastewater Treatment Process
Unit Operation: It is a process in which wastewater treated by Physical Method
Flow Diagram for Wastewater Treatment Process
Note: – All treatment plants have different equipment depending upon what they want to achieve or other several factors.
How many types of processes are there to treat waste water?
There are namely 3 major types of processes to treat waste water.
What is wastewater treatment?
According to Wikipedia, “Wastewater treatment is a process to convert wastewater – which is water no longer needed or suitable for its most recent use – into an effluent that can be either returned to the water cycle with minimal environmental issues or reused.
Why is primary wastewater treatment important?
The goal primary wastewater treatment is to extract organic and inorganic solids through sedimentation and the floating materials (scum) through skimming.
What is the most appropriate wastewater treatment plant?
The most appropriate wastewater treatment plant should be able to treat the wastewater and make an effluent which meets the chemical and microbiological guidelines but at the same time have low costs and low maintenance.
How long does it take to disinfect water?
Chlorine dosage of 5 to 15 mg/l is commonly used to disinfect water. Usually the contact time of chlorine and water is 30 minutes but it can go as long as 120 minutes for obtaining a specific quality of reclaimed water.
What is waste water?
Waste water is a common byproduct that is produced by humans through various activities involving such as bathing, showering, using the toilet, runoff of water and for cleaning purposes .
Why should personnel tasked with transportation be well protected while handling the contaminated water?
Personnel tasked with transportation should be well protected while handling the contaminated water to prevent the chances of cross-infection.
Stage 1: mechanical water treatment
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.
Stage 2: biological cleaning
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.
Stage 3: chemical wastewater treatment
In this stage of wastewater treatment, chemical processes are used for wastewater treatment. To this end, chemical compounds are used to achieve legally prescribed water standard values.
What is wastewater treatment?
Wastewater treatment is a process to treat sewage or wastewater to remove suspended solid contaminants and convert it into an effluent that can be discharged back to the environment with acceptable impact. The plants where the wastewater treatment process takes place are popularly known as Wastewater treatment plants, ...
Why is wastewater treatment important?
So, Wastewater treatment plants plays a major role in keeping environment clean and saving numerous lives.
How is wastewater formed?
Domestic wastewater is generated because of activities like bathing, washing, using the toilet, etc in residences, restaurants, and businesses. Surface rainwater runoff is generated due to the mixing of debris, grit, nutrients, and various chemicals. Industrial wastewater results because of chemical and manufacturing industry discharges. So, wastewater is essentially the used water that has been affected by domestic, commercial, or industrial use.
What is a sewage treatment plant?
Sewage treatment plants eliminate contaminants from wastewater and household sewage. It uses physical, chemical, and biological processes to remove physical, chemical and biological contaminants to make the water and solid waste reusable. Combined Effluent Treatment Plants are established where a cluster of small scale industries are present.
How is suspended solid removed from wastewater?
Suspended solid materials from the wastewater are removed by the sedimentation primary treatment. Other floatable materials like oils, fats, etc are removed using dissolved air floatation treatment. Primary wastewater treatment, in general, removes about 60% of suspended solids from wastewater.
Why is industrial wastewater considered domestic wastewater?
Industrial wastewater results because of chemical and manufacturing industry discharges. So, wastewater is essentially the used water that has been affected by domestic, commercial, or industrial use. Domestic wastewater is relatively easy to treat as compared to industrial wastewater due to its high-strength nature.
How to calculate the required average daily wastewater flow?
The required average daily wastewater flow for the design of new wastewater treatment plants needs to be calculated by multiplying the design population by the per capita rates of flow as determined from the table in Fig. 3.
Stage Two — Screening
- Removal of grit by flowing the influent over/through a grit chamber. Fine grit that finds its way into the influent needs to be removed to prevent the damage of pumps and equipment downstream (or impact water flow). Too small to be screened out, this grit needs to be removed from the grit …
Stage Three — Primary Clarifier
- Initial separation of solid organic matter from wastewater. Solids known as organics/sludge sink to the bottom of the tank and are pumped to a sludge digestor or sludge processing area, dried and hauled away. Proper settling rates are a key indicator for how well the clarifier is operating. Adjusting flow rate into the clarifier can help the operator adjust the settling rates and efficiency…
Stage Four — Aeration
- Air is pumped into the aeration tank/basin to encourage conversion of NH3 to NO3 and provide oxygen for bacteria to continue to propagate and grow. Once converted to NO3, the bacteria remove/strip oxygen molecules from the nitrate molecules and the nitrogen (N) is given off as N2↑ (nitrogen gas). At the heart of the wastewater treatment process is the encouragement and …
Stage Five — Secondary Clarifier
- Treated wastewater is pumped into a secondary clarifier to allow any remaining organic sediment to settle out of treated water flow. As the influent exits the aeration process, it flows into a secondary clarifier where, like the primary clarifier, any very small solids (or fines) sink to the bottom of the tank. These small solids are called activated sludge and consist mostly of active …
Stage Six — Chlorination
- Chlorine is added to kill any remaining bacteria in the contact chamber. With the enhanced concentration of bacteria as part of the aeration stage, there is a need to test the outgoing effluent for bacteria presence or absence and to disinfect the water. This ensures that higher than specified concentrations of bacteria are not released into the environment. Chlorinationis the m…
Stage Seven — Water Analysis & Testing
- Testing for proper pH level, ammonia, nitrates, phosphates, dissolved oxygen, and residual chlorine levels to conform to the plant’s NPDES permit are critical to the plant’s performance. Although testingis continuous throughout the wastewater treatment process to ensure optimal water flow, clarification and aeration, final testing is done to make sure the effluent leaving the p…
Stage Eight — Effluent Disposal
- After meeting all permit specifications, clean water is reintroduced into the environment. Although testingis continuous throughout the wastewater treatment process to ensure optimal water flow, clarification and aeration, final testing is done to make sure the effluent leaving the plant meets permit specifications. Plants that don`t meet permit discharge levels are subject to fines and po…
Collection of Wastewater from The Community
Odor Control of Wastewater
- The first task of the treatment plant is to remove as much as foul smelling substances from the waste water and to control the spread of odorin the treatment facility and the corresponding region surrounding the plant. This is so that the area around the treatment facility along with the treatment facility and the personnel working in the facility can be free of the bad odor. The contr…
Screening of Wastewater
- Large solid materials which are usually disposed by the masses into the waste water can block equipment and machines which are to treat the water. Hence, they are removed by machines and sorted out separately (A large sieve could be an alternative to this). These solid waste materials are then sent to be stored in landfills. However, if they are made of recycled products, only then …
Treatment Processes of Wastewater
- The water is now ready for treatment. Treatment is usuallycarried out in multiple stages like Primary, Secondary and Tertiary stages ofwastewater treatment.
Treatment of Solids
- The solids which were extracted during the treatment of the water are then directed to digesters. The purpose of the digesters is to heat the solids in an anaerobic environment, this leads to the production of methane gas. Other important nutrient rich bio-solids are also produced which can be recycled and used. Methane gas produce can be used to run the digesters or it can be used f…
Final Treatment
- The final treatment requires the use of highly skilled labor which can run and handle equipment and chemicals necessary for this step. The final wastewater treatment removes more than 99 percent impuritiesmaking the water as close as possible to regular drinking water. However, this process is highly expensive and not all treatment facilities are able to carry out this process. Thi…
Disinfection
- After treatment is concluded, there might still be some disease causing microorganism present in the water thus making it necessary to remove them by disinfecting the water. The process of disinfection requires the use of chemicals such as chlorine, sodium hypochlorite, and other disinfectants. The most common agent used in disinfection is chlorine which has been explaine…