{"id":1266,"date":"2026-07-17T16:31:52","date_gmt":"2026-07-17T13:01:52","guid":{"rendered":"https:\/\/hormonex.online\/?page_id=1266"},"modified":"2026-07-19T05:01:25","modified_gmt":"2026-07-19T01:31:25","slug":"extended-aeration-eaas-wastewater-treatment-package","status":"publish","type":"page","link":"https:\/\/polypayesh.com\/en\/extended-aeration-eaas-wastewater-treatment-package\/","title":{"rendered":"Extended Aeration (EAAS) Wastewater Treatment Package"},"content":{"rendered":"\t\t
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Extended Aeration (EAAS) Wastewater Treatment Package<\/h1>\t\t\t\t<\/div>\n\t\t\t\t
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The EAAS wastewater treatment package, sometimes also known in the market as EASS, is a biological treatment system based on the activated sludge process and extended aeration. This process is used for treating domestic and sanitary wastewater in projects such as villas, residential complexes, office buildings, hotels, lodges, schools, workshop camps, and complexes outside the urban sewer network.<\/p>\n\n

In the extended aeration wastewater treatment package, aerobic microorganisms decompose the organic matter present in the wastewater using the oxygen supplied by the blower and diffuser. The mixture of water and sludge then enters the settling section so that the sludge is separated from the effluent and the output water is prepared for disinfection or supplementary treatment.<\/p>\n\n

By reviewing the wastewater flow rate, the number of people, the type of use, the project space, the installation conditions, and the required output effluent quality, Poly Payesh designs and builds the EAAS wastewater treatment package to suit the needs of each project.<\/p>\n\n

What Is the EAAS System?<\/h2>\n

EAAS stands for Extended Aeration Activated Sludge. In this method, the wastewater is kept in contact with the activated sludge and oxygen for a longer time so that the decomposable organic matter is reduced by the aerobic bacteria.<\/p>\n

The extended aeration process is one of the well-known methods for treating domestic and sanitary wastewater and is especially widely used in small and medium wastewater treatment packages. This system can be designed as buried or above-ground and with a polyethylene, metal, fiberglass body, or other structures.<\/p>\n

The main goal of the EAAS package is to reduce organic pollutants, suspended solids, odor, and part of the decomposable pollutants of the wastewater so that the output effluent, after passing through the required stages, can be considered for discharge or reuse in accordance with the project standard.<\/p>\n\n\"\"\n\n

How Does the EAAS Wastewater Treatment Package Work?<\/h2>\n

The operation of the extended aeration wastewater treatment package is based on the controlled contact of the wastewater with the activated sludge in the presence of oxygen. In a conventional design, the process can include the following stages:<\/p>\n\n

    \n
  1. Receiving and pre-treating the wastewater<\/li>\n
  2. Equalizing the flow rate and pollution load if needed<\/li>\n
  3. Extended aeration and biological treatment<\/li>\n
  4. Secondary settling<\/li>\n
  5. Returning the activated sludge and disposing of excess sludge<\/li>\n
  6. Final disinfection<\/li>\n
  7. Storing, discharging, or transferring the effluent to supplementary treatment<\/li>\n<\/ol>\n\n

    The order, the tank volumes, and the equipment of each stage must be determined according to the wastewater quality, the design flow rate, the operating conditions, and the output standard.<\/p>\n\n\"\"\n\n

    Operating Stages of the Extended Aeration System<\/h2>\n\n

    1. Wastewater Inflow and Pre-treatment<\/h3>\n

    Domestic and sanitary wastewater enters the system after being collected from restrooms, bathrooms, kitchens, sinks, laundry, and service areas.<\/p>\n

    In many projects, before the wastewater enters the aeration tank, using equipment such as a screen (trash rack), grit chamber, grease trap, or equalization tank can be considered. This equipment helps reduce the entry of coarse particles, control flow fluctuation, and protect the subsequent equipment.<\/p>\n\n

    2. Aeration and Biological Treatment<\/h3>\n

    The aeration tank is the main part of the EAAS wastewater treatment package. In this section, air is supplied by the blower and distributed into the wastewater through fine-bubble diffusers.<\/p>\n

    The injected oxygen provides the conditions needed for the activity of the aerobic bacteria. These microorganisms consume and decompose part of the organic matter present in the wastewater.<\/p>\n

    As a result of this process, the following can be reduced:<\/p>\n\n

      \n
    • Part of the decomposable BOD and COD<\/li>\n
    • The organic matter present in the wastewater<\/li>\n
    • Part of the settleable suspended solids<\/li>\n
    • Odors caused by anaerobic decomposition of the wastewater<\/li>\n
    • The pollution load entering the subsequent treatment stages<\/li>\n<\/ul>\n\n

      The aeration time, the blower capacity, the diffuser type, the amount of dissolved oxygen, and the tank volume must be chosen based on an engineered design.<\/p>\n\n

      3. Formation of Activated Sludge<\/h3>\n

      In the extended aeration process, a combination of microorganisms and biological solids forms in the wastewater, which is called activated sludge.<\/p>\n

      The activated sludge plays the main role in decomposing organic matter. To maintain the stable performance of the system, the amount of sludge, the settling condition, the sludge age, and the aeration conditions must be reviewed periodically.<\/p>\n

      Correct management of the activated sludge can help maintain the effluent quality, reduce performance fluctuation, and prevent problems such as poor settling or a decline in the system’s efficiency.<\/p>\n\n

      4. Secondary Settling<\/h3>\n

      After the mixture of wastewater and sludge leaves the aeration tank, the flow enters the secondary settling unit or clarifier.<\/p>\n

      In this section, the activated sludge is separated from the effluent. The heavier particles settle to the bottom of the tank, and the clearer water exits from the upper part.<\/p>\n

      Secondary settling is one of the most important stages in the final quality of the effluent; because if this unit performs poorly, part of the sludge may exit the system along with the output effluent.<\/p>\n\n

      5. Return of Activated Sludge and Disposal of Excess Sludge<\/h3>\n

      Part of the sludge settled in the settling unit is returned to the aeration tank through the sludge return pump (RAS). This maintains the population of active microorganisms in the treatment process.<\/p>\n

      Another part of the sludge leaves the system as excess sludge (WAS). Regular disposal of excess sludge is essential to prevent excessive accumulation of solids and to maintain the biological balance.<\/p>\n\n

      6. Final Disinfection<\/h3>\n

      If the required output effluent quality requires a reduction of microbial contamination, the effluent enters the disinfection stage after settling.<\/p>\n

      The common disinfection methods include the following:<\/p>\n\n

        \n
      • Chlorination<\/li>\n
      • Ultraviolet (UV) irradiation<\/li>\n
      • Using disinfectants suitable for the project<\/li>\n<\/ul>\n\n

        The choice of disinfection method must be made according to the effluent quality, the type of final use, the operating requirements, and the desired standard.<\/p>\n\n\"\"\n\n

        Main Components of the EAAS Wastewater Treatment Package<\/h2>\n

        The components of the EAAS wastewater treatment package vary depending on the capacity, the installation location, and the project conditions; but a common system can include the following equipment:<\/p>\n\n

          \n
        • Screen (trash rack) or pre-treatment equipment<\/li>\n
        • Equalization tank if needed<\/li>\n
        • Aeration tank<\/li>\n
        • Aeration blower<\/li>\n
        • Fine-bubble diffusers<\/li>\n
        • Air distribution piping<\/li>\n
        • Secondary settling tank or clarifier<\/li>\n
        • Sludge return pump (RAS)<\/li>\n
        • Excess sludge disposal pump (WAS)<\/li>\n
        • Sludge storage tank if needed<\/li>\n
        • Disinfection system<\/li>\n
        • Electrical panel and control equipment<\/li>\n
        • Level and pressure sensors and monitoring equipment<\/li>\n
        • Inspection manhole and vent<\/li>\n
        • Treated effluent storage tank if needed<\/li>\n
        • Sewage pumping station, if gravity inflow is not possible<\/li>\n<\/ul>\n\n

          Advantages of the Extended Aeration Wastewater Treatment Package<\/h2>\n

          If the system is properly designed, installed, and operated, the EAAS package can have the following advantages:<\/p>\n\n

            \n
          • Suitable for treating domestic and sanitary wastewater<\/li>\n
          • A relatively simpler structure than some more complex processes<\/li>\n
          • The ability to be designed in various capacities<\/li>\n
          • The possibility of buried or above-ground execution<\/li>\n
          • The ability to be used in residential, office, accommodation, and workshop projects<\/li>\n
          • The possibility of being equipped with an electrical panel and automatic control<\/li>\n
          • The ability to connect to a disinfection system and supplementary treatment<\/li>\n
          • The possibility of use in polyethylene, metal, or fiberglass packages<\/li>\n
          • Good access to the main equipment such as the blower, pump, and diffuser<\/li>\n
          • The possibility of modular design for some projects and capacity expansion in the future<\/li>\n<\/ul>\n\n\"\"\n\n

            Limitations and Important Points in Operation<\/h2>\n

            The EAAS wastewater treatment package needs regular operation and maintenance for proper performance. The most important points are:<\/p>\n\n

              \n
            • The blower and aeration system must operate continuously or according to the design schedule.<\/li>\n
            • A long-term power outage can affect the performance of the aerobic process.<\/li>\n
            • Excess sludge must be discharged and managed at the appropriate time.<\/li>\n
            • The quality of the inlet wastewater must be consistent with the design basis of the system.<\/li>\n
            • The entry of corrosive chemicals, excess oil, solvents, or inhibitory materials can reduce biological activity.<\/li>\n
            • The diffusers, pumps, and electrical panel need periodic servicing and inspection.<\/li>\n
            • A capacity below the real need can cause a decline in effluent quality.<\/li>\n
            • Reusing the effluent can only be decided after reviewing the output quality and its compliance with the relevant standard.<\/li>\n<\/ul>\n\n

              The Difference Between EAAS and Conventional Activated Sludge<\/h3>\n

              EAAS is part of the activated sludge family, but in the extended aeration process, the contact time of the wastewater and the activated sludge is usually considered longer.<\/p>\n

              In conventional activated sludge, the design may be done for higher loading and less retention time. But in extended aeration, the goal is to create a process with lower loading and longer aeration time so that more suitable conditions are provided for the decomposition of organic matter and biological stability.<\/p>\n

              The choice between conventional activated sludge and extended aeration must be made based on the capacity, the type of wastewater, the project space, the energy cost, the level of operation, and the required effluent quality.<\/p>\n\n

              The Difference Between EAAS and SBR<\/h3>\n

              In the EAAS wastewater treatment package, the treatment process is usually carried out continuously in separate aeration and settling tanks.<\/p>\n

              But in the SBR process, the stages of filling, aeration, settling, and decanting are usually carried out in one reactor on a time schedule.<\/p>\n

              EAAS can be suitable for projects that need a continuous structure and simpler operation; while SBR is an option worth considering in some projects with limited space or a need for cyclical control.<\/p>\n\n

              The Difference Between EAAS and MBBR<\/h3>\n

              In the EAAS system, treatment is carried out mainly based on the suspended activated sludge in the aeration tank.<\/p>\n

              But in the MBBR process, moving media are used for biofilm growth. These media provide more surface for the growth of microorganisms and can, in some projects, help increase the biological capacity of the system.<\/p>\n

              The choice between EAAS and MBBR must be made based on the wastewater analysis, the available space, the required effluent quality, the flow fluctuations, the operating cost, and the maintenance conditions.<\/p>\n\n

              The Difference Between EAAS and A2O<\/h3>\n

              The EAAS process is used more for reducing organic matter and treating domestic and sanitary wastewater.<\/p>\n

              But the A2O process, by creating anaerobic, anoxic, and aerobic zones, is designed for projects where, in addition to removing organic matter, controlling nitrogen and phosphorus is also more important.<\/p>\n

              Therefore, A2O is usually more complex in terms of process control and required equipment, and its choice must be made based on the wastewater analysis and the output standard.<\/p>\n\n\"\"\n\n

              Applications of the EAAS Wastewater Treatment Package<\/h2>\n

              The extended aeration wastewater treatment package can be used in various projects, including:<\/p>\n\n

                \n
              • Villas and garden villas<\/li>\n
              • Residential complexes<\/li>\n
              • Office buildings<\/li>\n
              • Towers and construction projects<\/li>\n
              • Hotels and lodges<\/li>\n
              • Schools and educational centers<\/li>\n
              • Workshop camps<\/li>\n
              • Civil construction projects<\/li>\n
              • Tourism complexes<\/li>\n
              • Restaurants and service complexes after reviewing the type of wastewater<\/li>\n
              • Sites outside the range of the urban sewer network<\/li>\n
              • Organizational and office projects<\/li>\n
              • Small towns and semi-centralized complexes<\/li>\n<\/ul>\n\n

                Polyethylene EAAS Package<\/h2>\n

                The EAAS wastewater treatment package can be designed and executed with a polyethylene body. Using polyethylene tanks in suitable projects offers advantages such as resistance to corrosion, lower weight, easier transport, and a suitable execution speed.<\/p>\n

                The polyethylene package can be executed as buried or above-ground; but choosing this model must be done according to the soil conditions, the groundwater level, the applied loads, the installation location, the need for structural anchoring, and the executive requirements of the project.<\/p>\n

                For more details, see the “Polyethylene Wastewater Treatment Package” page.<\/p>\n\n\"\"\n\n

                EAAS Wastewater Treatment Package: Buried or Above-Ground?<\/h2>\n\n

                Buried EAAS Package<\/h3>\n

                In the buried model, the main tanks are installed below ground level. This method is suitable for projects that have surface-space limitations or prefer the equipment not to be visible.<\/p>\n

                Possible advantages of the buried model:<\/p>\n\n

                  \n
                • Better use of the site space<\/li>\n
                • Reducing the visual impact of the equipment<\/li>\n
                • Greater protection of the body against direct sunlight<\/li>\n
                • Suitable for some residential and villa projects<\/li>\n<\/ul>\n\n

                  Above-Ground EAAS Package<\/h3>\n

                  In the above-ground model, the tanks and equipment are installed on the ground surface. This method can be considered for projects where excavation is limited, the groundwater level is high, or easier access for servicing is needed.<\/p>\n

                  The choice between the buried and above-ground models must be made according to the ground conditions, the execution cost, the project space, the wastewater inflow route, and access for maintenance.<\/p>\n\n\"\"\n\n

                  How Is the Capacity of the EAAS Wastewater Treatment Package Determined?<\/h2>\n

                  Choosing the capacity of the EAAS package must be done based on the real information of the project. The most important factors include the following:<\/p>\n\n

                    \n
                  • The number of people using it<\/li>\n
                  • The type of use of the project<\/li>\n
                  • The average and maximum wastewater flow rate<\/li>\n
                  • The amount of water consumption<\/li>\n
                  • The quality of the inlet wastewater<\/li>\n
                  • The operating hours of the complex<\/li>\n
                  • The flow fluctuation over the course of the day<\/li>\n
                  • The space available for installation<\/li>\n
                  • Whether the system is buried or above-ground<\/li>\n
                  • The groundwater level and soil conditions<\/li>\n
                  • The required output effluent standard<\/li>\n
                  • The need for effluent reuse<\/li>\n
                  • The possibility of capacity expansion in the future<\/li>\n<\/ul>\n\n

                    For an exact design, it is better to provide the technical team with the project information, the installation site plan, the number of people, and, if possible, the wastewater analysis.<\/p>\n\n\"\"\n\n

                    What Factors Does the Price of the EAAS Wastewater Treatment Package Depend On?<\/h2>\n

                    The price of the extended aeration wastewater treatment package is not limited to a fixed figure and depends on the real specifications of the project.<\/p>\n

                    The most important factors affecting the price are:<\/p>\n\n

                      \n
                    • The package capacity in cubic meters per day<\/li>\n
                    • The type and quality of the inlet wastewater<\/li>\n
                    • The body material of the package<\/li>\n
                    • Whether the system is buried or above-ground<\/li>\n
                    • The number and volume of tanks<\/li>\n
                    • The type of blower and diffuser<\/li>\n
                    • The type of sludge return and disposal pumps<\/li>\n
                    • The electrical panel and the level of automation<\/li>\n
                    • The need for a PLC and control equipment<\/li>\n
                    • The need for disinfection or supplementary treatment<\/li>\n
                    • The need for a pumping station, grease trap, or equalization tank<\/li>\n
                    • The transport, installation, and piping conditions of the project<\/li>\n
                    • The available space and the executive limitations of the installation site<\/li>\n<\/ul>\n\n

                      For an exact price estimate, the required capacity, the type of wastewater, the installation conditions, and the expected effluent quality must be specified.<\/p>\n\n\"\"\n\n

                      Design and Construction of the EAAS Package by Poly Payesh<\/h2>\n

                      By reviewing the technical specifications of each project, Poly Payesh designs and builds the EAAS wastewater treatment package based on the real conditions of the site.<\/p>\n

                      In the design stage, the following are reviewed:<\/p>\n\n

                        \n
                      • The type of use of the project<\/li>\n
                      • The flow rate and pollution load of the wastewater<\/li>\n
                      • The quality of the inlet wastewater<\/li>\n
                      • The required capacity<\/li>\n
                      • The installation location and available space<\/li>\n
                      • The possibility of buried or above-ground execution<\/li>\n
                      • The required aeration and control equipment<\/li>\n
                      • The need for supplementary treatment or disinfection<\/li>\n
                      • The operation and maintenance conditions<\/li>\n
                      • The possibility of increasing capacity in the future<\/li>\n<\/ul>\n\n

                        The goal of the design is to choose a system that, in addition to meeting the project’s needs, is also suitable in terms of execution, maintenance, energy consumption, and operating cost.<\/p>\n\n

                        To receive specialized consultation, a technical review of your project, and a price quote for the EAAS wastewater treatment package, get in touch with the experts at Poly Payesh.<\/strong><\/blockquote>\n\n

                        Frequently Asked Questions About the EAAS Wastewater Treatment Package<\/h2>\n\n

                        What is EAAS?<\/h3>\n

                        EAAS stands for Extended Aeration Activated Sludge and refers to the wastewater treatment process based on activated sludge with extended aeration.<\/p>\n\n

                        Are EASS and EAAS the same?<\/h3>\n

                        In some sources and in the market, the term EASS is used to refer to the extended aeration system; but the more common technical name of the process is EAAS, or Extended Aeration Activated Sludge.<\/p>\n\n

                        What type of wastewater is the EAAS package suitable for?<\/h3>\n

                        This system is mainly suitable for treating domestic and sanitary wastewater in villas, residential complexes, buildings, hotels, schools, camps, and projects outside the urban sewer network.<\/p>\n\n

                        Can the EAAS package be used for industrial wastewater?<\/h3>\n

                        For some industrial effluents of a biodegradable nature and after a careful review of the wastewater analysis, this process can be considered. However, many industrial wastewaters need pre-treatment or dedicated units.<\/p>\n\n

                        Does the EAAS package need electricity?<\/h3>\n

                        Yes. The blower, pumps, electrical panel, and control equipment need electricity for the system to operate. In sensitive projects, providing emergency power can be considered.<\/p>\n\n

                        Is the output effluent of the EAAS package reusable?<\/h3>\n

                        With correct design, suitable operation, the required disinfection, and confirmation of the output quality based on the relevant standard, reusing the effluent for purposes such as green-space irrigation can be considered.<\/p>\n\n

                        What information is needed to request a price for the EAAS package?<\/h3>\n

                        The type of use, the number of people, the approximate wastewater flow rate, the project location, the installation space, the need for buried or above-ground execution, the electrical information, and the required output effluent quality are important pieces of information for design and price estimation.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

                        Extended Aeration (EAAS) Wastewater Treatment Package The EAAS wastewater treatment package, sometimes also known in the market as EASS, is a biological treatment system based on the activated sludge process and extended aeration. This process is used for treating domestic and sanitary wastewater in projects such as villas, residential complexes, office buildings, hotels, lodges, schools, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1266","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/pages\/1266","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/comments?post=1266"}],"version-history":[{"count":11,"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/pages\/1266\/revisions"}],"predecessor-version":[{"id":2281,"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/pages\/1266\/revisions\/2281"}],"wp:attachment":[{"href":"https:\/\/polypayesh.com\/en\/wp-json\/wp\/v2\/media?parent=1266"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}