How Does Sequencing Batch Reactor Work - Coursework Example

Name Task How does Sequencing Batch Reactor Work?’ Date How does Sequencing Batch Reactor Work?’ Introduction Treatment of waste water has been a challenge for many years due to the varying chemical and physical properties and stringent effluent regulations. Many of these difficulties are handled through the treatment systems using activated sludge. Given the lack of online computer controls, continuous flow systems are mostly used for these purposes as well as sequencing batch processes (Jung, 2004, p. 276) .Sequencing Batch Reactors are a form of an activated sludge process for waste water treatments. They treat waste water including sewage and output from anaerobic digesters as well as biological treatment facilities in batches (Jung, 2004, p. 274). Background information Artificial intelligence has been available, and this has made the option of an SBR process to be more attractive and this provides for better controls as well as results in the waste water treatment. It is a fill and draw activated sludge form of a sludge treatment system. The processes involved may SBR process may be identical to the conventional activated sludge systems, but SBR tends to be compact and time oriented system. Another difference is that all the steps are conducted sequentially in the same tank (Fernández, et.al, .2013, p. 565). During the process, oxygen is boiled through the mixture of waste water so as to reduce the organic matter in the water. The treated effluent can then be discharged to surface waters or even for land use (Keller, Watts & Chong, 2000, p.92) SBR is designed so as to operate under non-steady conditions. It operates in a true batch mode that has aeration and settlement of sludge both taking place in the same tank (Jung, 2004, p. 274) . The SBR tank conducts its functions of sedimentation and aeration in a time sequence instead of doing it in the conventional sequence of continuous flow systems. It can be designed with the ability to treat large volumes of waste water (Lowell, 2005, p.49) SBRs tend to produce sludge that have good settling properties and this provides the influent wastewater to be admitted in a controlled manner. The majority of aeration equipment of sequencing batch reactors includes jet, coarse bubble and fine bubble aeration systems (Mojiri et.al, 2014). Statement of purpose Many nations, companies and other institutions are in most cases faced with the problem of water treatment. This report gives a substantial analysis and the way in which sequencing batch reactors are used to treat dirty water for home and industrial use. The specific steps followed are discussed in this report. Sequencing Batch Reactor Process cycles The operating principles of a sequencing batch reactor process are characterized in six discrete periods which are: anoxic fill, aerated fill, react, settle, decant and idle. (Norcross, 1992, p.93): Mixing is done mechanically without the need of air. When the tank is being filled, the inlet valve is opened. This stage is also referred to as the anoxic stage. Mixed liquor is aerated during the second stage through using floating or fixed mechanical pumps Mojiri et.al, (2014). It can also be done by transferring air into fine bubble diffusers that are to the floor of the tank. In the third stage, no aeration or mixing is done, and it is in this stage that settling down of the suspended solids starts. In the fourth stage the outlet valve opens, and the clean supernatant liquor comes out of the tank (Ketchum, 2000, p. 89) . Anoxic fill The incoming waste water is distributed evenly throughout the settled sludge by the process of influent distribution manifold so as to provide good contact between microorganisms, as well as the substrate. The influent is then pumped or allowed to flow by the force of gravity. Most of this period takes place without aeration so as to create an environment that will favor the procreation of microorganisms which has goo settling features (Jung, Jin-Young, 2004. P. 347) . Aerated fill In this step, mixed liquor is drawn through the manifold. It is then combined with the influent flow in the motive liquid pump and then discharged out as a motive liquid to the jet aerator. This step marks the beginning of the feast period. In the feast period, the microorganisms are in contact with the substrate and large amounts of oxygen are provided so as to facilitate the consumption of the substrate. Nitrification and de-nitrification take place at the start of this stage (Lowell, 2005, p.142).This step ends when the tank if full or even when the maximum filling time is reached. React During this period, the process of aeration continues until the there is total biodegradation of BOD and nitrogen in the process. In this stage, all the substrate is consumed, and it leads to the star of the famine stage. During this stage, some microorganisms will perish due to the lack of food and also helps reduce the volumes of the settling sludge. The length of the aeration process determines the degree and rate of BOP consumption (Norcross, 1992, p.163). Settle The aeration process is discontinued at this stage. Solids are separated leaving clear and treated effluent to float above the sludge blanket. During this clarifying period, liquids are not supposed to enter or even leave the tank so as to avoid turbulence in the tank (Jung, 2004, p. 274). Decant This period is characterized by the removal of treated effluent from approximately two feet below the surface of the mixed liquor by the solids that are floating excluding the decanter (Ketchum, 2000, p. 102) .This removal is conducted without disturbing the settled sludge. Idle The time in this stage is used to waste sludge or execute backwashing of the jet aerator. The wasted sludge is then pumped to the anaerobic digester so as to reduce the volumes of the sludge to be discarded off (Norcross, 1992, p.198). The rate and frequency of the wasting sludge range between once in each cycle to once every two to three months and this depends on the system design. Consider the graphic below: Equipment used for aeration Jet aeration Header This equipment offers crucial advantages in the process of SBR because of its flexibility, effective oxygen transfer as well as ensuring a good contact between the substrates and the available microorganisms (Ketchum, 2000, p. 138) . One of its major characteristics is that it can mix without aerating. Thus, it can provide for anoxic and aerated mix periods at the same time. The equipment has a header that works in conjunction with a computer to control the aeration process and this makes more oxygen to be availed at higher glows rather than at lower flows (Lowell, 2005, p.168) .It does this by measuring the rates of change in the flow level in the reactor. B. Decanter Decanting is best attained through solids but not decanters. The floating decanter is one of the most effective and efficient equipment and contains a plug valve loaded with springs and operated by hydraulic differentials. The decanter is kept about sixteen inches below the scum by a float, thus avoiding the decanting of floating matter. SBR has recognized advantages over other activated sludge processes (Norcross, 1992, p.200). They include: significant decline of the overall footprint of the whole facility. Lessening of complexities of hydraulic complexities linked to flow distribution to multiple process tanks, there is eradication of segregated return activated sludge pumping or transferring, there is doing away with additional tank and concrete for independent processes such as clarification, construction sequencing is simplified to minimize current plant operations, there is easing of potential expansions and finally SBR manufacturer provides programmable logic controls (PLC) that offer detailed operational control of process systems to free the operators to work the system in lieu of performing tasks that consume time such as effluent weir cleaning (Keller, Watts & Chong, 2000, p.201) Configuration of SBR system The main components of an SBR system include the reactor tank, inlet, outlet, aeration and mixing arrangements as well as the operations controller. There is a significant diversity in the reactor tank configuration of SBR systems. The configurations exist in two main ways, the first being race-track channels with trapezoidal configuration (Fernández, et.al, .2013, p. 568). The width of the channel is selected for the purposes of ease of construction. The selection of the channel depth is affected by the type of aerators to be used. Horizontal rotors mounted with float are used for mixing and aeration. The mechanism of decant consists of a cast iron bell mouth which is connected by a 200mm diameter and a flexible hose to the outlet chamber. The main disadvantage of this system is that the configuration is extremely large and requires a lot of space (Ketchum, 2000, p. 164) Consider this graphic: The second configuration is in the form of single rectangular shape tanks with a minimum length to width ratio of 3:1. In addition, is often recommended so as to prevent short circuiting and the disruption of sludge during the phases of settle and decant (Fernández et.al, 2013) This is crucial primarily for the system where the process of fill is continuous, but the decant phase is intermittent. In cases where both the fill and decant phases are intermittent, the length to width ratio would not have much importance (Ketchum, 2000) . Consider this graphic which explains the second configuration in detail. In this configuration, the number of SBRs in parallel is determined by the design influent flow rates. In theory, there is no limit on the size and number of tanks used in the system. An SBR with just a single tank can be quite unusual for the common applications. SBR systems with single tanks are only possible when upstream influent storage is envisaged (Lowell, 2005, p.209) In these cases, a second tank will not be necessary since fill phase would end either naturally or by stopping the discharge from the storage facility. Clearly phases of react, settle and draw would have to be completed even before the wastewater flow resumes. (Fernandez, et.al, .2013, p. 563). In cases where waste streams are relatively large and are of continuous nature without large changes, multi task systems will be more effective (Chambers, 1993, p.186). Conclusion Multi task SBR systems are common for the normal municipal and industrial waste water treatment and mostly where the fill phase is not intended to be overlapping with the phase of draw. Due to the ease of use and the advantages of the sequencing batch reactors, firms and industries are urged to embrace these services so as to treat waste for use in homes and industries. Bibliography Fernández, et.al, .2013. Aerobic biodegradation of a mixture of mono substituted phenols in a sequencing batch reactor. Journal of Hazardous Materials.Vol.260. http://www.researchgate.net/profile/Isaac_Fernandez/publication/243966968_Aerobic_biodegradation_of_a_mixture_of_monosubstituted_phenols_in_a_sequencing_batch_reactor/links/0c9605280b20d80553000000.pdf New England Interstate Water Pollution Control Commission, Lowell. MA .2005. "Sequencing Batch Reactor Design and Operational Considerations."New York Ciuty. Norcross, K.L. 1992. "Sequencing Batch Reactors-An Overview." Water Science and Technology. vol. 26. https://www.neiwpcc.org/neiwpcc_docs/sbr_manual.pdf Chambers, B. 1993. "Batch Operated Activated Sludge Plant for Production of High Effluent Quality at Small Works." Water Science and Technology. vol. 28, no. 10 http://www.iwaponline.com/wst/02810/wst028100251.htm Keller, J., Watts, S. & Chong. 2000. Full-scale demonstration of biological nutrient removal in a single SBR tank process. Narbonne, France. http://espace.library.uq.edu.au/view/UQ:148851 Ketchum, Jr. L. H. 2000. Design and Physical features of SBR reactors. Proceedings of the 2nd International Symposium of International Water Association (IWA) on Sequencing Batch Reactor Technology. Narbonne, France. http://www.eolss.net/sample-chapters/c07/e6-144-11.pdf Mojiri, Amin ; etal,. 2014. Powdered ZELIAC augmented sequencing batch reactors (SBR) process for co-treatment of landfill leachate and domestic wastewater Journal of Environmental Management, 2014, Vol.139, p.1-14. Jung, Jin-Young; Chung, Yun-Chul ; Shin, Hang-Sik ; Son, Dae-Hee Water Research, 2004, Vol.38(2), pp.347-354. https://sites.google.com/site/kaisteerl/research-area/wastewater-treatment Read More

The majority of aeration equipment of sequencing batch reactors includes jet, coarse bubble and fine bubble aeration systems (Mojiri et.al, 2014). Statement of purpose Many nations, companies and other institutions are in most cases faced with the problem of water treatment. This report gives a substantial analysis and the way in which sequencing batch reactors are used to treat dirty water for home and industrial use. The specific steps followed are discussed in this report. Sequencing Batch Reactor Process cycles The operating principles of a sequencing batch reactor process are characterized in six discrete periods which are: anoxic fill, aerated fill, react, settle, decant and idle.

(Norcross, 1992, p.93): Mixing is done mechanically without the need of air. When the tank is being filled, the inlet valve is opened. This stage is also referred to as the anoxic stage. Mixed liquor is aerated during the second stage through using floating or fixed mechanical pumps Mojiri et.al, (2014). It can also be done by transferring air into fine bubble diffusers that are to the floor of the tank. In the third stage, no aeration or mixing is done, and it is in this stage that settling down of the suspended solids starts.

In the fourth stage the outlet valve opens, and the clean supernatant liquor comes out of the tank (Ketchum, 2000, p. 89) . Anoxic fill The incoming waste water is distributed evenly throughout the settled sludge by the process of influent distribution manifold so as to provide good contact between microorganisms, as well as the substrate. The influent is then pumped or allowed to flow by the force of gravity. Most of this period takes place without aeration so as to create an environment that will favor the procreation of microorganisms which has goo settling features (Jung, Jin-Young, 2004. P. 347) .

Aerated fill In this step, mixed liquor is drawn through the manifold. It is then combined with the influent flow in the motive liquid pump and then discharged out as a motive liquid to the jet aerator. This step marks the beginning of the feast period. In the feast period, the microorganisms are in contact with the substrate and large amounts of oxygen are provided so as to facilitate the consumption of the substrate. Nitrification and de-nitrification take place at the start of this stage (Lowell, 2005, p.142).This step ends when the tank if full or even when the maximum filling time is reached.

React During this period, the process of aeration continues until the there is total biodegradation of BOD and nitrogen in the process. In this stage, all the substrate is consumed, and it leads to the star of the famine stage. During this stage, some microorganisms will perish due to the lack of food and also helps reduce the volumes of the settling sludge. The length of the aeration process determines the degree and rate of BOP consumption (Norcross, 1992, p.163). Settle The aeration process is discontinued at this stage.

Solids are separated leaving clear and treated effluent to float above the sludge blanket. During this clarifying period, liquids are not supposed to enter or even leave the tank so as to avoid turbulence in the tank (Jung, 2004, p. 274). Decant This period is characterized by the removal of treated effluent from approximately two feet below the surface of the mixed liquor by the solids that are floating excluding the decanter (Ketchum, 2000, p. 102) .This removal is conducted without disturbing the settled sludge.

Idle The time in this stage is used to waste sludge or execute backwashing of the jet aerator. The wasted sludge is then pumped to the anaerobic digester so as to reduce the volumes of the sludge to be discarded off (Norcross, 1992, p.198). The rate and frequency of the wasting sludge range between once in each cycle to once every two to three months and this depends on the system design. Consider the graphic below: Equipment used for aeration Jet aeration Header This equipment offers crucial advantages in the process of SBR because of its flexibility, effective oxygen transfer as well as ensuring a good contact between the substrates and the available microorganisms (Ketchum, 2000, p. 138) .

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