Wastewater treatment methods

Articles

Types of wastewater are mainly treated and disinfected in three different ways, which include physical, chemical, and biological treatment.
Physical purification
Physical treatment is the first step in wastewater treatment, which is mostly used for the treatment of industrial and factory wastewater, which contains materials of heavy industrial and harmful materials. This method includes littering, granulation, sedimentation, aeration, filtration and disinfection.
Garbage collection
The first stage is water treatment, from which 30 to 40% of solids and suspended particles in the water are separated. There are different types of garbage collectors, including basket, rod, mechanical and rotary garbage collectors.
Seedling
The sand grains in the treated effluent are made in three stages using the granulation method, and are removed from the water stream.
ته‌شنینی
At this stage, the flow of treated water, after entering the settling tank, settles the grains with a diameter of more than 10 microns. Physical sedimentation is the most widely used operation of a wastewater treatment plant.
Aeration
By adding air to the aeration stage, biodegradation, the growth of microorganisms and, consequently, the loss of organic matter occur.
Air diffuser
Diffusers or air nozzles are used as a special ventilation tool in the biological reactor of sanitary and industrial wastewater treatment. The smaller the size of the air diffuser bubbles, the faster the ventilation. Diffusers are divided into three groups in terms of shape: disc, tubular and plate.
Filtration
Solid particles that were not removed in the previous steps are separated at this stage by passing through a variety of filters.
Disinfection
In each treatment plant, after the end of the last stage, we need disinfection to remove pathogens. The most common methods of wastewater disinfection are chlorine and ultraviolet disinfection.
Chemical refining
Chemical treatment is much more complex than the physical method. The most important chemical methods of wastewater treatment are precipitation, coagulation and oxidation.
ترسیب
Chemical precipitation is the most common method for removing soluble metals from industrial wastewater containing metals that affect the quality of the effluent.
Coagulation
The purpose of coagulation and flocculation is the use of coagulants in the separation of colloidal and soluble particles from wastewater that has a negative electric charge.
Chemical oxidation
This method is also used in water and wastewater treatment, which adds a kind of pure oxygen compounds to water or wastewater. Chemical oxidation is done in both classical and advanced methods.
Biological treatment
In biological treatment, which uses a variety of biological materials and bacteria, it is divided into two types: sticky and suspended growth. This method is always more popular because it produces less cost and sludge.
Anaerobic wastewater treatment
In the UASB (Up Flow Anaerobic Sludge Blanket) method, as the name implies, they treat wastewater with the help of anaerobic pathogenic bacteria.
The ABR (Anaerobic Baffled Reactor) method using baffled anaerobic reactors plays an important role in the wastewater treatment process. The most important feature of this process is the high speed of purification compared to other anaerobic methods.
The UAFB (Up Flow Anaerobic Fixed Bed) method, or upstream adhesive growth method, is a simple anaerobic method that does not require advanced equipment and technology.
Aerobic wastewater treatment
This process is one of the main methods of treating human sanitary wastewater. Non-use of chemicals in this method makes it a permanent advantage over other methods of wastewater treatment. There are different types of activated sludge process, some of which we will mention.
Conventional active process
Among all types of activated sludge processes, conventional activated sludge process with mold flow is the most used in wastewater treatment. In fact, the flow in a conventional activated sludge process is a combination of a complete and mold mixing process.
Extended Aeration
This process is used to treat industrial wastewater, which often contains complex soluble organic matter. One of the advantages of this process is the long residence time, which protects the system from organic load shocks.
Gradual aeration process
The gradual aeration system is very similar to wastewater treatment plants. This method is more suitable for communities up to 100,000 people and provides more optimal conditions.
Complete Mixed Activated Sludge
In this system, sewage is deposited and return activated sludge enters the aeration pond from several points. The operation of this process is relatively simple and the concentration of organic matter in it is low.
Contact Stabilization Process
In this method, two separate aeration tanks are used for wastewater treatment. After settling in the secondary pond, the biological clots leave the system and return to the other part of the stabilization pond.
Cross process
The cross process is a modified form of the aeration process for nitrogen-deficient wastewater.
Pure oxygen process
The use of a 3 or 4 stage closed reactor in this process is the most obvious feature of this method. Important advantages of this method are the reduction of space and the amount of exhaust gases, if necessary, odor control and VOC.
Sludge dryer
Every process that takes place in nature and industry, in addition to the product of the process, leaves behind a waste material that is commonly called sludge in wastewater treatment and must be disposed of properly. To get rid of sludge, it is usually dried by dewatering, which is called the sludge drying process.
Wetland in wastewater treatment
One of the most suitable methods in wastewater treatment