Wastewater Recycle & Reuse Plant in Bangladesh
Wastewater Recycle & Reuse Plant in Bangladesh.
We are pioneer in Wastewater Recycle & Reuse Plant in Bangladesh. Green Dot Limited is introducing modern and economical technology in Wastewater Recycle & Reuse Plant in Bangladesh, Zero Discharge Plant in Bangladesh and Effluent Treatment Plant ( ETP) in Bangladesh
There is a water crisis today. But the crisis is not about having too little water to satisfy our needs. It is a crisis of managing water so badly that billions of people - and the environment - suffer badly." World Water Vision Report
With the current state of affairs, correcting measures still can be taken to avoid the crisis to be worsening. There is an increasing awareness that our freshwater resources are limited and need to be protected both in terms of quantity and quality. This water challenge affects not only the water community, but also decision-makers and every human being. "Water is everybody's business" was one the key messages of the 2nd World Water Forum.
All wastewater are different, So it is necessary to work with a team that can combine comprehensive knowledge with practical experience in the fields of chemistry, biology, hydraulics, mechanical processes/equipment, instrumentation and control, materials handling and plant layout.
Green Dot Limited can deliver on all the process components that make up a wastewater treatment plant. We have cultivated expertise for designing and implementing such kind of Waste Water Recycle and Reuse Plant, Zero Discharge Plant to save the environment.
Our services include process design, process optimization, plant operations and control systems. Green Dot can also assist clients to develop long-term, sustainable solutions for wastewater treatment including biosolids and other solids waste treatment and disposal, and effluent reuse.
"Services those are available here:"
- Facilities of raw water analysis
- Facilities of planning and development
- Alternatives and comparison analysis
- Life cycle assessment
- Comprehensive facility evaluations
- Bio-solids management planning
- Comparative benchmarking
- Treatability studies and pilot studies
- Process design
- Concept design
- Detailed design for bid/tender
- Design-build owner's engineering services
- Design-build and alliance partnerships
- Construction phase engineering services
- Construction management and inspection
- Startup and commissioning services
- Process and energy use optimization
- Computerized operations and maintenance manuals
- Pretreatment programs
- Permitting and regulatory assistance
- Utility master planning and asset management
- Economic analysis and rate studies
- Program management
www.greendotbd.com
Zero Discharge Wastewater Treatment Plant in Bangladesh
Zero Discharge Wastewater Treatment plant, Zero Discharge Plant, Zero Liquid Discharge Plant, Wastewater Recycle Plant, Waste Water Plant, Water Treatment Plant
Green Dot Limited is the leader of Wastewater Treatment Plant, Effluent Treatment Plant, Sewage Treatment Plant and all kinds of Water Treatment Plant in Bangladesh. We always reserve modern technology and International Brand in our stock.
Zero Discharge Wastewater Treatment Plant:
Wastewater reuse is a common practice in developing countries of Asia and Africa and wastewater recycling is common in water scarce regions of the developed countries such as the Australia, Middle East, south west of US, and in regions with severe restrictions on disposal of treated wastewater effluents, such as Florida, coastal or inland areas of France and Italy, and densely populated European countries such as England and Germany. Even in high rainfall countries like Japan, whose mean annual precipitation of 1,714 millimeters (mm), urban wastewater reuse is common due to high population density in some regions, which suffer from water shortages. The developed countries have generated techniques and guidelines for safe reuse of wastewater, which can be adopted by the developing countries.
Zero Discharge Wastewater Treatment systems recycle all the discharged liquid simultaneously, ensuring zero effluent or waste water.
We offer state-of-the-art Zero Discharge Wastewater Treatment systems, Zero Liquid Discharge Plant designed and developed in accordance with the latest market requirements. These fully integrated and automated systems incorporate mechanical vapor compression brine concentrator, forced circulation crystallizer and solids dewatering. These systems employ membrane processes, evaporative processes, or a combination of both the processes to achieve Zero Discharge Wastewater Treatment from the plants.
"Advantages of Reuse or Zero Discharge Plant:" By using wastewater after Zero Discharge Wastewater Treatment Plant as a resource rather than a waste product you can:
- Reduce water bills
- Use fewer water resources
- Irrigate the garden during drought or water restrictions
- Cut down the amount of pollution going into waterways
- Help save money on new infrastructure for water supplies and wastewater treatment
- Decrease demand on infrastructure for sewage transport, treatment and disposal, allowing it to work better and last longer.
We build Zero discharge plant for various industries using modern technologies like reverse osmosis, multi – effect evaporation, incineration etc. The basic principle of zero discharge plant is to concentrate the impurities of effluent either by reverse osmosis/ nano - filtration/ evaporation and drying the concentrated effluent in flaker dryer/ spray dryer/ incinerator etc.
The selection of technology based on the type of effluent, available excess steam at the site, cost of treatment and capital cost required for the project.
For Further information and prices regarding Zero Discharge Wastewater Treatment Plant, Zero Liquid Discharge, please contact with our expertises:
LAN SHAN RO WATER PURIFIER FOR HOME USE
LAN SHAN RO WATER PURIFIER SYSTEM (SEVEN STAGES MINERAL)
Green Dot Water Research Laboratory in Bangladesh
Green Dot Water Research Laboratory
Green Dot Water Research Laboratory, established in June, 2015, is one of the finest water testing laboratory in Bangladesh.
We are offering a wide range of water quality tests in an available price.
Phone: +88 02 989858, +88 02 9880152, +88 01678 797 996
Email: chemist@greendotbd.com
Website: http://www.greendotbd.com
Facebook: https://www.facebook.com/greendotbd
Green Dot Water Research Laboratory, established in June, 2015, is one of the finest water testing laboratory in Bangladesh.
We are offering a wide range of water quality tests in an available price.
Phone: +88 02 989858, +88 02 9880152, +88 01678 797 996
Email: chemist@greendotbd.com
Website: http://www.greendotbd.com
Facebook: https://www.facebook.com/greendotbd
What is Reverse Osmosis Part 01?
Reverse Osmosis is a technology that is used to remove a large majority of contaminants from water by pushing the water under pressure through a semi-permeable membrane. This topic for those audience that has little of no experience with What is Reverse Osmosis ? and will attempt to explain the basics in simple terms that should leave the reader with a better overall understanding of Reverse Osmosis technology.
For example, you have the following:
The RO system is producing 75 gallons per minute (gpm) of permeate. You have 3 RO vessels and each vessel holds 6 RO membranes. Therefore you have a total of 3 x 6 = 18 membranes. The type of membrane you have in the RO system is a Dow Filmtec BW30-365. This type of RO membrane (or element) has 365 square feet of surface area.
To find the flux (Gfd):
The flux is 16 Gfd.
This means that 16 gallons of water is passed through each square foot of each RO membrane per day. This number could be good or bad depending on the type of feed water chemistry and system design. Below is a general rule of thumb for flux ranges for different source waters and can be better determined with the help of RO design software. If you had used Dow Filmtec LE-440i RO membranes in the above example, then the flux would have been 14. So it is important to factor in what type of membrane is used and to try and keep the type of membrane consistent throughout the system.
To be continue...
Perceptive of Reverse Osmosis
Reverse Osmosis, commonly referred to as RO, is a process where you demineralize or deionize water by pushing it under pressure through a semi-permeable Reverse Osmosis Membrane.
Osmosis Technoligy
To understand the purpose and process of Reverse Osmosis you must first understand the naturally occurring process of Osmosis.
Osmosis is a naturally occurring phenomenon and one of the most important processes in nature. It is a process where a weaker saline solution will tend to migrate to a strong saline solution. Examples of osmosis are when plant roots absorb water from the soil and our kidneys absorb water from our blood.
Below is a diagram which shows how osmosis works. A solution that is less concentrated will have a natural tendency to migrate to a solution with a higher concentration. For example, if you had a container full of water with a low salt concentration and another container full of water with a high salt concentration and they were separated by a semi-permeable membrane, then the water with the lower salt concentration would begin to migrate towards the water container with the higher salt concentration.
A semi-permeable membrane is a membrane that will allow some atoms or molecules to pass but not others. A simple example is a screen door. It allows air molecules to pass through but not pests or anything larger than the holes in the screen door. Another example is Gore-tex clothing fabric that contains an extremely thin plastic film into which billions of small pores have been cut. The pores are big enough to let water vapor through, but small enough to prevent liquid water from passing.
Reverse Osmosis is the process of Osmosis in reverse. Whereas Osmosis occurs naturally without energy required, to reverse the process of osmosis you need to apply energy to the more saline solution. A reverse osmosis membrane is a semi-permeable membrane that allows the passage of water molecules but not the majority of dissolved salts, organics, bacteria and pyrogens. However, you need to 'push' the water through the reverse osmosis membrane by applying pressure that is greater than the naturally occurring osmotic pressure in order to desalinate (demineralize or deionize) water in the process, allowing pure water through while holding back a majority of contaminants.
Below is a diagram outlining the process of Reverse Osmosis. When pressure is applied to the concentrated solution, the water molecules are forced through the semi-permeable membrane and the contaminants are not allowed through.
How does Reverse Osmosis work?
Reverse Osmosis works by using a high pressure pump to increase the pressure on the salt side of the RO and force the water across the semi-permeable RO membrane, leaving almost all (around 95% to 99%) of dissolved salts behind in the reject stream. The amount of pressure required depends on the salt concentration of the feed water. The more concentrated the feed water, the more pressure is required to overcome the osmotic pressure.
The desalinated water that is demineralized or deionized, is called permeate (or product) water. The water stream that carries the concentrated contaminants that did not pass through the RO membrane is called the reject (or concentrate) stream.
As the feed water enters the RO membrane under pressure (enough pressure to overcome osmotic pressure) the water molecules pass through the semi-permeable membrane and the salts and other contaminants are not allowed to pass and are discharged through the reject stream (also known as the concentrate or brine stream), which goes to drain or can be fed back into the feed water supply in some circumstances to be recycled through the RO system to save water. The water that makes it through the RO membrane is called permeate or product water and usually has around 95% to 99% of the dissolved salts removed from it.
It is important to understand that an RO system employs cross filtration rather than standard filtration where the contaminants are collected within the filter media. With cross filtration, the solution passes through the filter, or crosses the filter, with two outlets: the filtered water goes one way and the contaminated water goes another way. To avoid build up of contaminants, cross flow filtration allows water to sweep away contaminant build up and also allow enough turbulence to keep the membrane surface clean.
What will Reverse Osmosis remove from water?
Reverse Osmosis is capable of removing up to 99%+ of the dissolved salts (ions), particles, colloids, organics, bacteria and pyrogens from the feed water (although an RO system should not be relied upon to remove 100% of bacteria and viruses). An RO membrane rejects contaminants based on their size and charge. Any contaminant that has a molecular weight greater than 200 is likely rejected by a properly running RO system (for comparison a water molecule has a MW of 18). Likewise, the greater the ionic charge of the contaminant, the more likely it will be unable to pass through the RO membrane. For example, a sodium ion has only one charge (monovalent) and is not rejected by the RO membrane as well as calcium for example, which has two charges. Likewise, this is why an RO system does not remove gases such as CO2 very well because they are not highly ionized (charged) while in solution and have a very low molecular weight. Because an RO system does not remove gases, the permeate water can have a slightly lower than normal pH level depending on CO2 levels in the feed water as the CO2 is converted to carbonic acid.
Reverse Osmosis is very effective in treating brackish, surface and ground water for both large and small flows applications. Some examples of industries that use RO water include pharmaceutical, boiler feed water, food and beverage, metal finishing and semiconductor manufacturing to name a few.
Reverse Osmosis Performance & Design Calculations
There are a handful of calculations that are used to judge the performance of an RO system and also for design considerations. An RO system has instrumentation that displays quality, flow, pressure and sometimes other data like temperature or hours of operation. In order to accurately measure the performance of an RO system you need the following operation parameters at a minimum:
- Feed pressure
- Permeate pressure
- Concentrate pressure
- Feed conductivity
- Permeate conductivity
- Feed flow
- Permeate flow
- Temperature
Salt Rejection %
This equation tells you how effective the RO membranes are removing contaminants. It does not tell you how each individual membrane is performing, but rather how the system overall on average is performing. A well-designed RO system with properly functioning RO membranes will reject 95% to 99% of most feed water contaminants (that are of a certain size and charge). You can determine effective the RO membranes are removing contaminants by using the following equation:
The higher the salt rejection, the better the system is performing. A low salt rejection can mean that the membranes require cleaning or replacement.
The higher the salt rejection, the better the system is performing. A low salt rejection can mean that the membranes require cleaning or replacement.
Salt Passage %
This is simply the inverse of salt rejection described in the previous equation. This is the amount of salts expressed as a percentage that are passing through the RO system. The lower the salt passage, the better the system is performing. A high salt passage can mean that the membranes require cleaning or replacement.
Recovery %
Percent Recovery is the amount of water that is being 'recovered' as good permeate water. Another way to think of Percent Recovery is the amount of water that is not sent to drain as concentrate, but rather collected as permeate or product water. The higher the recovery % means that you are sending less water to drain as concentrate and saving more permeate water. However, if the recovery % is too high for the RO design then it can lead to larger problems due to scaling and fouling. The % Recovery for an RO system is established with the help of design software taking into consideration numerous factors such as feed water chemistry and RO pre-treatment before the RO system. Therefore, the proper % Recovery at which an RO should operate at depends on what it was designed for. By calculating the % Recovery you can quickly determine if the system is operating outside of the intended design. The calculation for % Recovery is below:
For example, if the recovery rate is 75% then this means that for every 100 gallons of feed water that enter the RO system, you are recovering 75 gallons as usable permeate water and 25 gallons are going to drain as concentrate. Industrial RO systems typically run anywhere from 50% to 85% recovery depending the feed water characteristics and other design considerations.
For example, if the recovery rate is 75% then this means that for every 100 gallons of feed water that enter the RO system, you are recovering 75 gallons as usable permeate water and 25 gallons are going to drain as concentrate. Industrial RO systems typically run anywhere from 50% to 85% recovery depending the feed water characteristics and other design considerations.
Concentration Factor
The concentration factor is related to the RO system recovery and is an important equation for RO system design. The more water you recover as permeate (the higher the % recovery), the more concentrated salts and contaminants you collect in the concentrate stream. This can lead to higher potential for scaling on the surface of the RO membrane when the concentration factor is too high for the system design and feed water composition.
The concept is no different than that of a boiler or cooling tower. They both have purified water exiting the system (steam) and end up leaving a concentrated solution behind. As the degree of concentration increases, the solubility limits may be exceeded and precipitate on the surface of the equipment as scale.
For example, if your feed flow is 100 gpm and your permeate flow is 75 gpm, then the recovery is (75/100) x 100 = 75%. To find the concentration factor, the formula would be 1 ÷ (1-75%) = 4.
A concentration factor of 4 means that the water going to the concentrate stream will be 4 times more concentrated than the feed water is. If the feed water in this example was 500 ppm, then the concentrate stream would be 500 x 4 = 2,000 ppm.
The concept is no different than that of a boiler or cooling tower. They both have purified water exiting the system (steam) and end up leaving a concentrated solution behind. As the degree of concentration increases, the solubility limits may be exceeded and precipitate on the surface of the equipment as scale.
For example, if your feed flow is 100 gpm and your permeate flow is 75 gpm, then the recovery is (75/100) x 100 = 75%. To find the concentration factor, the formula would be 1 ÷ (1-75%) = 4.
A concentration factor of 4 means that the water going to the concentrate stream will be 4 times more concentrated than the feed water is. If the feed water in this example was 500 ppm, then the concentrate stream would be 500 x 4 = 2,000 ppm.
Flux
For example, you have the following:
The RO system is producing 75 gallons per minute (gpm) of permeate. You have 3 RO vessels and each vessel holds 6 RO membranes. Therefore you have a total of 3 x 6 = 18 membranes. The type of membrane you have in the RO system is a Dow Filmtec BW30-365. This type of RO membrane (or element) has 365 square feet of surface area.
To find the flux (Gfd):
The flux is 16 Gfd.
This means that 16 gallons of water is passed through each square foot of each RO membrane per day. This number could be good or bad depending on the type of feed water chemistry and system design. Below is a general rule of thumb for flux ranges for different source waters and can be better determined with the help of RO design software. If you had used Dow Filmtec LE-440i RO membranes in the above example, then the flux would have been 14. So it is important to factor in what type of membrane is used and to try and keep the type of membrane consistent throughout the system.
| Feed Water Source | Gfd |
|---|---|
| Sewage Effluent | 5-10 |
| Sea Water | 8-12 |
| Brackish Surface Water | 10-14 |
| Brackish Well Water | 14-18 |
| RO Permeate Water | 20-30 |
*** Collected.
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