Industrial wastewater treatment steps must be done carefully so that the best result and output water can be delivered. In large factories , this work is done by experienced professionals. But it is better to know about the steps of industrial wastewater treatment before preparing the industrial wastewater treatment package and monitor the project implementation process.
pretreatment; Scavenging stage
The first step in industrial wastewater treatment is pre-treatment. Pre-treatment devices are designed and used to remove or crush solids, remove heavy mineral solids and oil or grease. In this phase, the following equipment is usually used:
- blackout
- chopper
- Mill
- Pre-aeration tanks
primary purification; Primary clarification to separate solid organic matter
In the stages of industrial wastewater treatment , most of the separation and removal of solid materials from wastewater is done using physical processes. The use of chemicals to help the sedimentation process in primary sedimentation tanks also leads to the removal of colloidal solids.
Biological activity is less important in this stage of industrial wastewater treatment, and the main purpose of primary treatment is to reduce the speed of wastewater flow so that solid materials reach the sediment and suspended materials reach the surface. These sedimentation reservoirs can be divided into the following four categories:
- Wastewater tanks
- Two-story tanks
- Simple sedimentation tanks with mechanical sludge removal
- Upstream clarifiers with mechanical sludge removal
When using chemicals, auxiliary units are also used, which include chemical injection units, mixing devices, and coagulators. The results of primary treatment, along with anaerobic decomposition of sludge, can be compared with the self-remediation stage. This process involves the removal of large suspended organic solids, which is usually done using the sedimentation method in settling ponds. The wastewater from this stage often has a high amount of suspended organic matter and high BOD. Sometimes, pretreatment and primary treatment are included in the same treatment category. Organic solids separated in sedimentation tanks are often decomposed, stabilized, or incinerated by anaerobic digestion in a tank. The remainder is also transported to landfills or soil conditioning.
secondary purification; aeration
In the secondary treatment stage of the industrial wastewater treatment stages , organic solids are decomposed into stable organic solids or minerals, mainly depending on aerobic microorganisms. Aerobic biologicals, also known as treatment reactors, are where organic matter is oxidized under the influence of aerobic bacteria. These units may include the following elements:
- Filters
- Aeration tanks
- Feeding with recirculating activated sludge
- Oxidation ponds
- Aerated wetlands
The equipment used in secondary treatment can be divided into the following four groups:
1/ Spray filters with secondary sedimentation tanks
2/ Activated sludge and modification with final settling tanks
3/ Intermittent sand filters
4/ Stabilization ponds
A critical step in the industrial wastewater treatment process , the step in which aerobic bacteria increases. These organic substances destroy bacteria quickly. Aeration Usually, after about 5 to 6 hours of aeration, the waste is sent to the final settling tank.
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Some settled materials, which are also called activated sludge, are returned to the aeration tank. Because this activated sludge has a large number of bacteria in it and will help in the consumption of organic substances and the increase of bacteria. Final settling tanks are used for settling bacteria. Purified water is chlorinated and discharged.
When this sludge is removed from the sedimentation tank and placed in the decomposition tank for some time, it may be disposed of. During the secondary treatment process, approximately 90% of organic matter is removed using millions of bacteria. After adding chlorine, the waste is sterilized and no longer has much pollution and is used for recycling in the industry.
disinfection; Sedimentation of organic sediments
In the disinfection stage of industrial wastewater treatment, primary, secondary and even final cleanings are not able to complete 100% cleaning of the pollution load, and for this reason, many organisms still remain in the waste. In order to prevent the spread of waterborne diseases, regulatory bodies need to remove these pathogenic organisms. Although most of these microorganisms are not pathogenic on their own, it should be considered that pathogens may potentially be present.
Therefore, when the wastewater is going to overflow to different areas for water supply, swimming or fishing, measures are taken to minimize the number of bacteria. Disinfection of wastewater is an effective solution to eliminate all pathogens.
Another way to remove these microorganisms is to sterilize POLYELECTROLYTE PACKAGE them. Theoretically, different physical and chemical methods can be used for this purpose. These measures are very effective and necessary in disinfecting wastewater and removing microorganisms.
Sludge treatment; disinfection
In the sludge treatment stage of the industrial wastewater treatment process, the discharge of solid materials from the wastewater in the primary and secondary treatment units, which is removed from the system along with water, is known as sewage sludge. The main purpose of this process is twofold: to remove part or all of the water in the sludge in order to reduce its volume and to break down the organic solids in a way that causes them to be converted into mineral solids or relatively stable organic solids. This operation is performed by a combination of two or more different methods.
- to thicken
- Decomposition with or without heat
- Drying on a sand bed (open or closed)
- Avoiding conditions with chemicals
- Vacuum filtration
- Thermal drying
- to burn
- Wet oxidation
- centrifuge
The organic waste and sludge separated from the water in the primary and secondary stages of treatment are recorded in an anaerobic process in a sludge decomposition tank and then disposed of. The main purpose of this process is to decompose the sludge, reduce spoilage and pathogenic contents and improve water characteristics. The sludge resulting from this decomposition is usually transported to the sea as fertilizer in the fields or by boat. Smaller amounts are typically used as fertilizer in agriculture, while larger amounts are incinerated or buried in landfills.
final purification; Drainage of water and disposal of solids
The final steps and final purification are necessary as a complementary step in the primary and secondary purification processes, in order to remove the remaining organic or mineral residues, and in some cases resistant and soluble substances. This process is used in various industries such as cooling systems, boiler feed, and process water. Also, it is used in agriculture, gardening, watering lawns and other fields.
Conclusion
Here, we tried to explain all the stages of industrial wastewater treatment to you in full. We hope it was useful for you.