Waste Water Treatment Plant
Effluent Treatment Plant (ETP) is a crucial wastewater treatment method that effectively purifies industrial wastewater, making it suitable for reuse. An ETP plant’s primary objective is to ensure safe water’s release into the environment. Depending on the specific industry, industrial effluents can contain a wide range of materials. Some effluents may consist of oils, industrial by-products, metals, radioactive wastes, grease, or even toxic substances such as cyanide. In the case of food and beverage factories, the effluents may contain degradable organic pollutants.
Due to the diverse impurities found in industrial wastewater, a specialized treatment technology known as ETP is required. UAL tailors the design of an effluent treatment plant to treat the effluents originating from different areas of the industrial facility. The treatment process for various effluents varies depending on their composition.
For instance, effluent from textile and chemical industries undergoes a series of operations, including coagulation, flocculation, aeration, and filtration techniques, mainly employing reverse osmosis. The effluent produced by these industries typically exhibits high levels of BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), pH, TSS (Total Suspended Solids), TDS (Total Dissolved Solids), and color materials.
The Effluent Treatment Plant plays a vital role in treating industrial wastewater to ensure its safe release into the environment. By employing specific treatment technologies and optimizing various unit operations, industries can effectively manage and reduce the volume of effluent produced. These efforts contribute to sustainable industrial practices and the preservation of our natural resources.
Specialized applications
Unitop provides various specialized equipment based on the requirement of client such as Membrane bio-reactors, Dissolved air flotation, packaged type ETP/STP.
The conventional method of Effluent Treatment Plant (ETP):
Effluent treatment plant is divided into different unit operations and processes.
Preliminary treatment– With the collection of combined effluent at one point of industrial area, it is pumped or transferred by gravity to screen chamber, the effluent is passed through oil & grease trap and collected in Equalization tank. In equalization tank, pH correction, cooling treatment, mixing of various effluent is done.
Primary treatment– Effluent from equalization tank is pumped to downstream process for primary treatment which is physico-chemical in nature, specifically to remove suspended matter, floating & emulsified oil, heavy metals etc.
Secondary treatment– After equalization or primary treatment dissolved organic substances BOD/COD shall be reduced by bacteriological activity. This biological activity shall be taken place in presence or absence of oxygen, i.e. aerobic or anaerobic treatment.
Tertiary treatment-After secondary treatment, remaining suspended solids, color particles, odor shall be removed in tertiary treatment. Microfiltration in the form of sand filtration followed by carbon filtration are the major components of this step.
Disinfection– Wastewater can carry pathogenic microorganisms, which may be harmful, if left untreated. Disinfection systems such as hypochlorite dosing, ozonation, UV disinfection.
Specialized applications– Unitop provides various specialized equipment based on the requirement of client such as Membrane bio-reactors, Dissolved air flotation, packaged type ETP/STP.
Recycling & zero liquid discharge– Considering the cost involved in Zero Liquid Discharge system, maximum recovery of waste water is planned in Reverse Osmosis Unit with necessary Ultrafiltration as pretreatment unit to Reverse Osmosis. Permeate recovery shall be 92-95% which can be used in production process. Minimum quantity & concentrated RO reject shall be sent for evaporation/ZLD.
Sludge/ Solid Disposal-Sludge from various stages of ETP/STP shall be collected & dewatered in the suitable dewatering equipment.Z
The Effluent Treatment Plant (ETP) process with Dissolved Air Flotation (DAF) and Membrane Bioreactor (MBR):
Effluent treatment plant is divided into different unit operations and processes.
- Preliminary Treatment:
a. Screening: The wastewater is passed through screens to remove large objects, debris, and solids.
b. Grit Removal: Grit chambers or grit removal systems are used to settle and remove heavy inorganic solids like sand, gravel, and grit.
c. Equalization: The wastewater is collected in an equalization tank to balance the flow and composition. - Dissolved Air Flotation (DAF):
a. Coagulation and Flocculation: Coagulants, such as alum or ferric chloride, are added to the wastewater to destabilize and clump the suspended particles. Polymer flocculants are then added to agglomerate the particles into larger flocs.
b. DAF Process: In the DAF unit, the wastewater is saturated with air under pressure, forming tiny air bubbles. These bubbles attach to the flocs and float them to the surface, where they are skimmed off as a sludge layer.
c. Sludge Handling: The sludge collected from the DAF unit is sent for further treatment or disposal. - Biological Treatment:
a. Anoxic Zone: In the first stage of the MBR process, an anoxic zone is created where the wastewater is mixed with activated sludge in the absence of oxygen. This promotes denitrification, converting nitrates to nitrogen gas.
b. Aerobic Zone: The wastewater, along with the mixed liquor suspended solids (MLSS) from the anoxic zone, is transferred to the aerobic zone. Here, aerobic bacteria break down organic matter present in the wastewater through the process of oxidation.
c. Membrane Bioreactor (MBR): The MBR system employs a membrane module submerged in the aerobic zone. The membrane acts as a physical barrier, allowing the treated water to pass through while retaining suspended solids, bacteria, and other contaminants. The MBR system provides excellent effluent quality due to its superior filtration capabilities. - Membrane Cleaning:
a. Backwashing: To maintain the performance of the membrane, periodic backwashing is conducted to remove accumulated solids and debris from the membrane surface.
b. Chemical Cleaning: In some cases, chemical cleaning is performed using specialized cleaning solutions to remove any foulants or biofilm that may adhere to the membrane surface. - Tertiary Treatment:
a. Filtration: After the MBR process, the treated effluent passes through additional filtration units, such as ultrafiltration membranes or multimedia filters, to further remove any remaining suspended solids and fine particles.
b. Disinfection: To ensure the elimination of pathogens and harmful microorganisms, disinfection methods like chlorination, UV disinfection, or ozonation are employed.
c. pH Adjustment: If necessary, the pH of the treated effluent is adjusted to meet regulatory requirements using chemicals like lime or sulfuric acid. - Sludge Management:
a. Sludge Handling: The excess sludge generated in the MBR system and DAF unit is collected and separated from the treated effluent.
b. Sludge Treatment: The collected sludge can undergo further treatment processes such as thickening, dewatering, and stabilization, depending on the specific requirements and regulations.
c. Sludge Disposal: The treated sludge is typically sent for disposal in landfills, incinerated, or used for agricultural purposes after meeting regulatory standards.
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