ADVANCE ENVIRONMENTAL
ENGINEERING CO.,LTD.
บทคัดย่อ
ระบบบำบัดน้ำเสียเติมอากาศตามแนวดงิ่ (Deep Shaft Reactor) เป็นระบบบำบัดน้ำเสียชนิดหนึ่งในกระบวนการ
บำบัดน้ำเสียแบบชีวภาพที่นิยมใช้กันมาก ทัง้ นี้เพราะระบบบำบัดน้ำเสียชนิดนี้ใช้พื้นที่ตามแนวราบในการบำบัดน้ำเสีย
น้อยที่สุด งานวิจัยที่นำเสนอได้ศึกษาถึงตัวแปรทางไฮโดรไดนามิคที่มีผลกระทบต่อระบบบำบัดน้ำเสียเติมอากาศตาม
แนวดงิ่ แบบแยกส่วน (Split Type) โดยได้จำลองถังของระบบบำบัดน้ำเสียชนิดนี้ให้มีความสูงและขนาดเส้นผ่าน
ศูนย์กลางเท่ากับ 3.5 เมตร และ 0.5 เมตรตามลำดับ ในงานวิจัยนี้ได้ทำการเปลี่ยนระยะความลึกของตัวพ่นอากาศด้าน
Riser โดยมีอัตราส่วนระยะความลึกของตัวพ่นอากาศต่อความลึกของน้ำเท่ากับ 0.454, 0.606 และ 0.909 ตามลำดับ
และทำการเปลี่ยนระยะความลึกของตัวพ่นอากาศด้าน Downcomer ที่อัตราส่วนระยะความลึกของตัวพ่นอากาศต่อ
ความลึกของน้ำเท่ากับ 0.303, 0.454, 0.606, 0.757 และ 0.909 ตามลำดับ พร้อมกับเปลี่ยนอัตราส่วนพื้นที่หน้าตัด
ด้าน Downcomer ต่อพื้นที่หน้าตัดทัง้ หมดเท่ากับ 0.204, 0.346 และ 0.5 ตามลำดับ จากผลการทดลองพบว่า การเพมิ่
อัตราการพ่นอากาศในด้าน Riser ตำแหน่งการติดตัง้ ตัวพ่นอากาศด้าน Riser ที่มีความลึกมากขึ้นและ พื้นที่หน้าตัด
ด้าน Downcomer ที่น้อยลงจะทำให้ฟองอากาศที่ถูกพ่นออกจากตัวพ่นอากาศด้าน Downcomer มีการเคลื่อนที่ลงมา
จากด้าน Downcomer มีค่ามากขึ้น ขณะที่อัตราการพ่นอากาศในด้าน Riser ที่มีค่าเหมาะสมและตำแหน่งการติดตัง้ ตัว
พ่นอากาศด้าน Riser ที่มีความลึกมากขึ้นจะทำให้ความเร็วของเหลวภายในถังมีค่าสูงขึ้นแต่ตำแหน่งของการติดตัง้ ตัว
พ่นอากาศด้าน Downcomer นั้นจะไม่มีผลกระทบต่อความเร็วของเหลวภายในถังเลยถ้าอัตราการพ่นอากาศในด้าน
Downcomer มีค่าต่ำ สุดท้ายเมื่อทำการเปรียบเทียบค่าตัวแปรทางไฮโดรไดนามิคจากการทดลองและจากสมการสมดุล
พลังงานพบว่า มีความสอดคล้องกัน
คำหลัก: กระบวนการบำบัดน้ำเสียแบบชีวภาพ ระบบบำบัดน้ำเสียเติมอากาศตามแนวดงิ่ แบบแยกส่วน และ ไฮโดร
ไดนามิค
Abstract
Deep shaft reactor is one of the biological waste water treatments and very popular among users due to
its requirement of minimal horizontal area for the installation. The study was done at variables of
hydrodynamic which were influential in the split-typed deep shaft reactor. In the model tank of which the
height and diameter are 3.5 meters and 0.5 meter respectively, the ratios of the depth of diffuser installed at
the riser side to the water level were changed to be 0.454, 0.606 and 0.909; on the other hand, those ratios
at the downcomer side were changed to be 0.303, 0.454, 0.606, 0.757 and 0.909. Furthermore, the ratios of
the cross sectional area of the downcomer side to that of the tank were adjusted to be 0.204, 0.346 and 0.5
respectively. From the experiment, it was found that the increase of air diffused at the riser side, the deeper
position of the diffuser installed at the riser side and the decrease of cross sectional area of the downcomer
side all made more air bubbles from the diffuser at the downcomer side move downward. Meanwhile, the
optimum air flow rate at the riser side and the deeper position of the diffuser installed at the riser side
caused liquid velocity inside the tank to rise, but the position of the diffuser at the downcomer side had little
effect to liquid velocity in case the air flow rate at the downcomer side was low. In comparison, the
hydrodynamic variables from the experiment and mathematic model are harmonious.
Keywords: Biological waste water treatments, Split-typed Deep Shaft Reactor and hydrodynamics.
Why Use Anaerobic Digestion?
The activated sludge process is a biological waste water treatment method in which micro-organisms are bunched together to form sludge flocs. The flocs develop spontaneously when the waste water is aerated. The waste water and the sludge flocs are mixed in the aeration tank. Most of the impurities in the waste water are suitable nutrients for the bacteria in the flocs. They take up the nutrients in their cells. When the treatment process is completed, sludge flocs and clean water are separated by settling of the flocs in the final clarifier.
What is advantage ?
It is to everyone’s advantage for a community to be able to treat its wastewater in the most economical way. The activated sludge process has the advantage of
• Producing a high quality effluent
• Reasonable operating and maintenance costs.
• Low construction cost.
• Relatively small land requirement compare to other aerobic system
The process
A basic activated sludge process consists of several interrelated components:
• An aeration tank where the biological reactions occur
• An aeration source that provides oxygen and mixing
• A tank, known as the clarifier, where the solids settle and are separated from treated wastewater
• A means of collecting the solids either to return them to the aeration tank, (return activated sludge RAS), or to remove them from the process (waste activated sludge WAS).
The activated sludge plant is the most popular biological treatment process for larger installations or small package plants being used today. These plants are capable of producing a high quality effluent for the price.
The activated sludge process is widely used by large cities and communities where large volumes of wastewater must be highly treated economically. Activated sludge process plants are good choices too for isolated facilities, such as hospitals or hotels, cluster situations, subdivisions, and small communities.
Anaerobic Digestion
Anaerobic digestion (AD) is a natural process and is the microbiological conversion of organic matter to methane in the absence of oxygen. The decomposition is caused by natural bacterial action in various stages. It takes place in a variety of natural anaerobic environments, including water sediment, water-logged soils, natural hot springs, ocean thermal vents and the stomach of various animals (e.g. cows). The digested organic matter resulting from the anaerobic digestion process is usually called digestate.
Anaerobic Process Plants
Anaerobic process plants produce conditions that encourage the natural breakdown of organic matter by bacteria in the absence of air. The process generates three main products:
Biogas - a mixture of carbon dioxide (CO2) and methane (CH4), which can be used to generate heat and/or electricity
Fibre - can be used as a nutrient-rich soil conditioner, and
Liquor - can be used as liquid fertiliser.
The process takes place in a digester; a warmed, sealed airless container. The digestion tank is warmed and mixed thoroughly to create the ideal conditions for biogas conversion.
During the digestion process 30 - 60% of the organic material is converted into biogas. It can be then be burned in a conventional gas boiler for heat or it can be burned in a more efficient combined heat and power (CHP) system, where heat and electricity are generated.
The digestate is stored and can be applied straight to land or it can be separated to produce fibre and liquor.
Why Use Anaerobic Digestion?
Anaerobic Digestion projects have several benefits, depending on the priorities of the plant management. The main reasons for developing an AD project are summarised below.
Reduction of pollution through integrated waste management
The products of AD produce less odour than farm slurry
Can reduce pollution of water courses by reducing run-off. Run-off is the liquid slurry which is sprayed onto farmland, but then drains into surface water. It can carry sediments and pollutants into the receiving waters.
AD can lessen the risks of the spread of disease and contamination by destroying bacteria, viruses and weed seeds.
Well-managed AD can decrease methane (CH4) release more effectively than conventional waste management, because the methane is converted into carbon dioxide (CO2), a less potent greenhouse gas.
The use of AD can aid industry to manage organic waste in a manner that is not detrimental to the surrounding area and will necessitate awareness of environmental regulations.
Deep Shaft Process
What is Deep Shaft
The deep-shaft activated sludge process is a unique modification of the activated sludge system. The main objective of this system is to increase the amount of dissolved oxygen available for biological activity. This can be achieved by increasing the rate of oxygen transfer from the gas phase to the liquid phase. The deep shaft configuration increases the partial pressure of oxygen, thereby causing a high saturation concentration in the reactor. In the deep-shaft process, owing to high oxygen availability, a higher organic loading can be accommodated with a comparatively low air supply. This reduces the energy and area requirements and lowers the overall cost of treatment. This technology has been successfully applied for the high-rate treatment of strongly polluted wastewater, as well as for the treatment of wastewater containing toxic or slowly biodegradable pollutants.
How does it work ?
The deep shaft process carries out the biochemical treatment of wastewater efficiently by dissolving oxygen in the air quickly into wastewater. The shaft having a bore of from 1m to 6m, is installed vertical in the ground as deep as 50m to 150m, and is divided into two sections by a cylindrical perpendicular wall: down-coming and up-rising section. The inflow is introduced to the top, and it goes down toward the shaft bottom as it is mixed with the circulating liquid in the shaft.
The air introduced into the down-coming section travels toward the bottom mixed with the circulating liquid which circulates in the shaft at the rate of 1 to 2 m/s, and by the time the air reaches the shaft bottom the most of it is dissolved into the liquid due to higher hydraulic pressure. Thus, the deep shaft process, being capable of producing dissolved oxygen of higher density, completes the biological treatment rapidly and positively.
Why Deep Shaft (Advantage)
Space saving
While the aeration tank of the standard activated sludge process is of flat type, the deep shaft process tank is installed in a deep vertical bore in the ground, the area required for installation is approximately 1/20 of that for the conventional type.
Energy saving
Compared with the standard activated sludge process, the oxygen utilization factor is higher anywhere from 5 to 9 times; hence, the air blown in can be in the order of 1/6 through 1/8. This tends to lower the running cost.
Effective for high density wastewater
Due to higher density of dissolved oxygen and higher oxygen utilization factor, the process is capable of handling high density wastewater and sewage effectively.
Less sludge
With ample supply of oxygen, the microorganisms are in very much active state; hence, the treatment capacity is large and the volume of sludge produced tends to be small.
Smooth restarting
Restarting of the system can be completed smoothly only in one day's time even after about 10 days' system shutdown.
Other favorable features
Capability to cope with load variation Operation not being influenced by the weather conditions Less odor generation
Activated sludge Process
The activated sludge process is a biological waste water treatment method in which micro-organisms are bunched together to form sludge flocs. The flocs develop spontaneously when the waste water is aerated. The waste water and the sludge flocs are mixed in the aeration tank. Most of the impurities in the waste water are suitable nutrients for the bacteria in the flocs. They take up the nutrients in their cells. When the treatment process is completed, sludge flocs and clean water are separated by settling of the flocs in the final clarifier.
What is advantage ?
It is to everyone’s advantage for a community to be able to treat its wastewater in the most economical way. The activated sludge process has the advantage of
• Producing a high quality effluent
• Reasonable operating and maintenance costs.
• Low construction cost.
• Relatively small land requirement compare to other aerobic system
The process
A basic activated sludge process consists of several interrelated components:
• An aeration tank where the biological reactions occur
• An aeration source that provides oxygen and mixing
• A tank, known as the clarifier, where the solids settle and are separated from treated wastewater
• A means of collecting the solids either to return them to the aeration tank, (return activated sludge RAS), or to remove them from the process (waste activated sludge WAS).
The activated sludge plant is the most popular biological treatment process for larger installations or small package plants being used today. These plants are capable of producing a high quality effluent for the price.
The activated sludge process is widely used by large cities and communities where large volumes of wastewater must be highly treated economically. Activated sludge process plants are good choices too for isolated facilities, such as hospitals or hotels, cluster situations, subdivisions, and small communities.
Anaerobic Digestion
Anaerobic digestion (AD) is a natural process and is the microbiological conversion of organic matter to methane in the absence of oxygen. The decomposition is caused by natural bacterial action in various stages. It takes place in a variety of natural anaerobic environments, including water sediment, water-logged soils, natural hot springs, ocean thermal vents and the stomach of various animals (e.g. cows). The digested organic matter resulting from the anaerobic digestion process is usually called digestate.
Anaerobic Process Plants
Anaerobic process plants produce conditions that encourage the natural breakdown of organic matter by bacteria in the absence of air. The process generates three main products:
Biogas - a mixture of carbon dioxide (CO2) and methane (CH4), which can be used to generate heat and/or electricity
Fibre - can be used as a nutrient-rich soil conditioner, and
Liquor - can be used as liquid fertiliser.
The process takes place in a digester; a warmed, sealed airless container. The digestion tank is warmed and mixed thoroughly to create the ideal conditions for biogas conversion.
During the digestion process 30 - 60% of the organic material is converted into biogas. It can be then be burned in a conventional gas boiler for heat or it can be burned in a more efficient combined heat and power (CHP) system, where heat and electricity are generated.
The digestate is stored and can be applied straight to land or it can be separated to produce fibre and liquor.
Why Use Anaerobic Digestion?
Anaerobic Digestion projects have several benefits, depending on the priorities of the plant management. The main reasons for developing an AD project are summarised below.
Reduction of pollution through integrated waste management
The products of AD produce less odour than farm slurry
Can reduce pollution of water courses by reducing run-off. Run-off is the liquid slurry which is sprayed onto farmland, but then drains into surface water. It can carry sediments and pollutants into the receiving waters.
AD can lessen the risks of the spread of disease and contamination by destroying bacteria, viruses and weed seeds.
Well-managed AD can decrease methane (CH4) release more effectively than conventional waste management, because the methane is converted into carbon dioxide (CO2), a less potent greenhouse gas.
The use of AD can aid industry to manage organic waste in a manner that is not detrimental to the surrounding area and will necessitate awareness of environmental regulations.
Commercial Benefits
AD can generate income by charging gate fees, selling biogas (as electricity or heat), liquor and/or fibre products.
AD can produce savings by avoiding the costs of synthetic fertilisers, soil conditioners and energy from other sources.
Legal and political objectives
Public opinion is changing, and demands the farming community consider the environment and minimise pollution when farming.
There are increased legislative and regulative measures being placed on farmers regarding local waste management.
Community issues
Anaerobic digestion projects can directly boost rural economies by creating jobs and indirectly through increasing disposable incomes in rural areas.
It can provide a waste management option with positive environmental and economic benefits.
Anaerobic digestion can also offer an opportunity to realise potential in local communities working together,stimulating new developments that are community owned and operated.
Chemical Treatment
What is chemical treatment ?
Treatment by this method uses various chemicals to destabilize, de-emulsify, or absorb into the oil phase of a metal removal fluid, thereby allowing the water and oil phases to separate.
At a minimum, one storage tank, one processing tank, and one oil-sludge tank are necessary. A processing tank should be large enough to handle at least one average day of flow. If the system is being set up for continuous flow, a series of cascading tanks with at least a half- hour retention time per tank is necessary.
A small laboratory bench with a dedicated pH meter and calibrating buffer solutions, a magnetic stirring mixer, chemicals used within the process and pipettes for measuring chemical additions are all good to have on site. Truck spill containment may be required for oil hauling pump-outs by a contract service.What are the advantages and disadvantages of chemical treatment?
Advantages:
•Energy consumption is low.
•Diluted solutions are easier to separate.
•Separation times can be very rapid (30 minutes).
บทคัดย่อ
ระบบบำบัดน้ำเสียเติมอากาศตามแนวดงิ่ (Deep Shaft Reactor) เป็นระบบบำบัดน้ำเสียชนิดหนึ่งในกระบวนการบำบัดน้ำเสียแบบชีวภาพที่นิยมใช้กันมาก ทั้งนี้เพราะระบบบำบัดน้ำเสียชนิดนี้ใช้พื้นที่ตามแนวราบในการบำบัดน้ำเสียน้อยที่สุด งานวิจัยที่นำเสนอได้ศึกษาถึงตัวแปรทางไฮโดรไดนามิคที่มีผลกระทบต่อระบบบำบัดน้ำเสียเติมอากาศตามแนวดิ่ง แบบแยกส่วน (Split Type) โดยได้จำลองถังของระบบบำบัดน้ำเสียชนิดนี้ให้มีความสูงและขนาดเส้นผ่านศูนย์กลางเท่ากับ 3.5 เมตร และ 0.5 เมตรตามลำดับ ในงานวิจัยนี้ได้ทำการเปลี่ยนระยะความลึกของตัวพ่นอากาศด้าน Riser โดยมีอัตราส่วนระยะความลึกของตัวพ่นอากาศต่อความลึกของน้ำเท่ากับ 0.454, 0.606 และ 0.909 ตามลำดับ และทำการเปลี่ยนระยะความลึกของตัวพ่นอากาศด้าน Downcomer ที่อัตราส่วนระยะความลึกของตัวพ่นอากาศต่อ ความลึกของน้ำเท่ากับ 0.303, 0.454, 0.606, 0.757 และ 0.909 ตามลำดับ พร้อมกับเปลี่ยนอัตราส่วนพื้นที่หน้าตัดด้าน Downcomer ต่อพื้นที่หน้าตัดทัง้ หมดเท่ากับ 0.204, 0.346 และ 0.5 ตามลำดับ จากผลการทดลองพบว่า การเพิ่มอัตรากาพ่นอากาศในด้าน Riser ตำแหน่งการติดตัง้ ตัวพ่นอากาศด้าน Riser ที่มีความลึกมากขึ้นและ พื้นที่หน้าตัดด้าน Downcomer ที่น้อยลงจะทำให้ฟองอากาศที่ถูกพ่นออกจากตัวพ่นอากาศด้าน Downcomer มีการเคลื่อนที่ลงมาจากด้าน Downcomer มีค่ามากขึ้น ขณะที่อัตราการพ่นอากาศในด้าน Riser ที่มีค่าเหมาะสมและตำแหน่งการติดตั้งตัวพ่นอากาศด้าน Riser ที่มีความลึกมากขึ้นจะทำให้ความเร็วของเหลวภายในถังมีค่าสูงขึ้นแต่ตำแหน่งของการติดตั้งตัวพ่นอากาศด้าน Downcomer นั้นจะไม่มีผลกระทบต่อความเร็วของเหลวภายในถังเลยถ้าอัตราการพ่นอากาศในด้าน Downcomer มีค่าต่ำ สุดท้ายเมื่อทำการเปรียบเทียบค่าตัวแปรทางไฮโดรไดนามิคจากการทดลองและจากสมการสมดุลพลังงานพบว่า มีความสอดคล้องกัน คำหลัก: กระบวนการบำบัดน้ำเสียแบบชีวภาพ ระบบบำบัดน้ำเสียเติมอากาศตามแนวดงิ่ แบบแยกส่วน และ ไฮโดรไดนามิค
Abstract
Deep haft reactor is one of the biological waste water treatments and very popular among users due to its requirement of minimal horizontal area for the installation. The study was done at variables of hydrodynamic which were influential in the split-typed deep shaft reactor. In the model tank of which the height and diameter are 3.5 meters and 0.5 meter respectively, the ratios of the depth of diffuser installed at the riser side to the water level were changed to be 0.454, 0.606 and 0.909; on the other hand, those ratios at the downcomer side were changed to be 0.303, 0.454, 0.606, 0.757 and 0.909. Furthermore, the ratios of the cross sectional area of the downcomer side to that of the tank were adjusted to be 0.204, 0.346 and 0.5respectively. From the experiment, it was found that the increase of air diffused at the riser side, the deeperposition of the diffuser installed at the riser side and the decrease of cross sectional area of the downcomerside all made more air bubbles from the diffuser at the downcomer side move downward. Meanwhile, theoptimum air flow rate at the riser side and the deeper position of the diffuser installed at the riser sidecaused liquid velocity inside the tank to rise, but the position of the diffuser at the downcomer side had littleeffect to liquid velocity in case the air flow rate at the downcomer side was low. In comparison, thehydrodynamic variables from the experiment and mathematic model are harmonious.Keywords: Biological waste water treatments, Split-typed Deep Shaft Reactor and hydrodynamics.