The Key Steps in Industrial Water Filtration
Industrial water filtration systems use processes that range from the straightforward to the complex. They work in a variety of ways to purify water. The full process of how this is done can sound a bit intimidating to the casual observer. However, the filtration system typically works in the following four steps:
i. Screening – As the source water enters the industrial water filtration systems, it is passed through a screen. The screen removes the large particles
from the water system. This prevents the systems from being clogged during the process of purification.
ii. Flocculation/Coagulation – This step involves the addition of chemicals to treat the impure water. The chemicals cause floc to form. Floc is a sticky substance that is made of small particles. This process makes these particles to sink to the bottom of the tank, where they are removed. Others float to the top and are skimmed off.
iii. Filtration – This is a very important part of the industrial water filtration systems. Floc is left in the initial filtration tank used at the
flocculation stage. Pumps push the water through the filters, where even more particles are removed from the water. For effectiveness, the filters are made from
crushed black walnut shell (NSF or BWS), cloth, carbon or sand.
iv. Disinfection – Once the water is filtered, pumps push it to a special tank for disinfection. The process of disinfection involves the use of chemicals to destroy any microorganisms that might have survived stage 3 (filtration). The most commonly used technologies for disinfection include the use of chlorine, reverse osmosis (RO), use of ultra-violet light (UV) and ultrafiltration.
The above steps are just a summary of the entire process. As noted earlier, industrial water filtration systems can be very complex. How each system is applied depends on the particular needs of the facility. The unique technologies used in each system will depend on the impurities being targeted for removal. However, there are many similarities in all the systems.=
Industrial Water Filtration Applications
1. Wastewater Treatment Systems
Wastewater treatment system converts raw sewage into streams that can be safely reused or discharged into the environment. The system protects the equipment and also prevents harm to human health and the environment. In addition, it helps your business avoid incurring the fines that are associated with the improper discharge of wastewater. The technologies applicable to wastewater treatment system depend on the composition of the facility’s waste stream. The compliance regulations imposed on the plant are also a major consideration in this matter.
How Do Wastewater Treatment Systems Work?
Each wastewater system operates based on its unique circumstances. These include floe re-use strategies, stream constituents and discharge regulations among other considerations. However, all the wastewater treatment systems generally follow these steps
i. Clarification – This first stage involves a number of steps. It precipitates silica and metal and removes solids from the solution. The entire process usually takes place in a number of tanks where chemicals are added, followed by flocculation, sedimentation, and filtration. These steps are used to remove the very small particles. Also, it is during this process that any special particles (silver, gold etc.) are retrieved from the solution.
ii. Disinfection – In this step, all kinds of dangerous pathogens are removed. These pathogens (viruses, fungi, and bacteria) can cause serious health issues
if released into the environment. They are found in plenty in wastewater. As such, if the wastewater were to be discharged without being disinfected a myriad of sicknesses and even death can affect humans, animals, and plants. Disinfection is thus a critical part of wastewater treatment systems.
iii. Softening – Lime softening is used to reduce the mineral and sulfate content in streams. To do so effectively, lime is used to raise the pH, thus encouraging the precipitation of the minerals and sulfate. The particles are thus ejected from the solution. In many cases, membrane softening is employed.
iv. Other Processes – Some specialized wastewater treatment processes may be employed to deal with peculiar issues. Such processes are often used to ensure
that wastewater treatment needs are fully catered for, depending on the facility. The specialized processes are used to remove certain organics or
metals and to cut down on TDS so that the water can be recycled.
v. Routing – After the wastewater is treated, it may be discharged into the local sewer or the environment. For this to happen, the facility must fully
comply with the regulations. Alternatively, the wastewater can be reused within the facility.
2. Raw Water Treatment Systems
Raw water is any untreated water from rivers, lakes, wells, groundwater, rains or any other natural source. Once treated, it is used for washing, rinsing, cooling, product formulations, and agriculture. It can also be consumed by people and animals.
Raw water treatment systems are used to enhance the production capacity of the equipment. The raw water is pretreated to prevent fouling, scaling or corroding downstream equipment. In addition, raw water has to be pretreated if it is to be used for cooling the boilers and towers. The treatment process aims to remove hardness, bacteria, iron, silica and other colloidal solids. Once this is done, the water can be used in production processes and even for human consumption.
How Do Raw Water Treatment Systems Work?
How the raw water treatment systems are applied differs in different facilities. It is dependent on the applications and goals of the installation. The following is what you should generally expect:
i. Intake – The raw water is introduced into the plant either through gravity or by being pumped. A metal grate or strong wire mesh is used to prevent big objects from finding their way into the system.
ii. Clarification – Clarification involves the use of several steps. It is meant to remove solids from the solution. Clarification involves the following:
a. Coagulation – the pH is adjusted to make particles clump together.
b. Flocculation – large particles are made from the smaller ones.
c. Sedimentation – the large particles are made to settle at the bottom of a tank known as gravity settler.
d. Filtration – a gravity sand filter is used to trap any small particles that might have escaped the above steps.
iii. Disinfection – Disinfection in mainly meant to remove any micro-organisms in the water. It can be accomplished through the use of heat, UV rays, membrane
filtration and by the use of chlorine or other disinfectants.
iv. Lime soda softening – Lime or lime soda is used to reduce the water hardness. Suitable quantities of lime or lime soda are added to the water. They raise the
pH, thus encouraging the sulfate and mineral content to precipitate.
v. IX (Ion Exchange) – An IX unit may be used to remove the hardness of raw water. The water is treated in a process that involves the use of acid cation resin
which traps the ions responsible for the water hardness.
vi. Membrane filtration – This involves the use of nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF). These processes have become more
affordable in the recent past. As a result, their demand has gone up.
vii. Routing – Once treated, the water is distributed through pumping. It can also be routed for use within the facility.
3. Cooling Tower Water Treatment Systems
When contaminated feed water comes into contact with components of the cooling tower, such components will be damaged. They can also be damaged by blowdown water and circulation water. Cooling tower treatment systems are primarily meant to prevent such an eventuality. The treatment rids the water of contaminants like biological material, iron, chlorides, hardness, sulfates, silica, TSS, and TDS.
If left untreated cooling tower feed water can cause such problems as corrosion, biological growth, scaling and fouling of the equipment. They will have a direct impact on productivity, the cost of repair and maintenance.
How Do Cooling Tower Water Treatment Systems Work?
The treatment systems remove harmful contaminants to make the water safe. How this is done depends on the type of cooling tower, and the
recommendations from the manufacturer on water quality. The treatment generally follows these steps:
i. Water Intake – It is common for some water to be lost within the system due to leaks, bleed to drain and evaporation. This water needs to be replaced with
cooling tower makeup water. The source of the makeup water is varied. It could be obtained from raw water, recycled wastewater, and municipal supplies amongst
others. This water may have to be treated for hardness, pH imbalance, and silica removal.
ii. Filtration – The water is filtered through a number of filters to remove organic material, turbidity and sediments. Many industry players now favor the
use of filtration before other methods. When done this way, it becomes cost-effective to maintain downstream equipment.
iii. Membrane/Resin Softening – A membrane or resin softener is used to remove any hardness from the source or makeup water. The contaminants responsible for hardness can cripple equipment through rust and scale deposits. Softening, therefore, is critical in improving the efficiency of the cooling tower.
iv. Addition of chemicals – Some of the chemicals added in this stage reduce acidity and prevent the growth of biological agents. Others prevent scaling in the pipes
and other components.
v. Side-stream filtration – Most cooling towers reuse the same water in their circulatory systems. For these, a side-stream filtration unit is important to
remove any contaminants that might have gotten into the water. The side-stream filtration unit comprises of multimedia filtration technology.
vi. Post-treatment options – The post-treatment options are dependent on the installation. If large quantities of cooling water are needed, the facility can
use blow down water with IX or RO. The water can then be recycled.
Other types of post-treatment options can be employed to cut down on the costs of disposal. Yet other systems are used to align the
discharge with local regulations.
4. Boiler Feed Water Treatment Systems
For boiler units to function at optimal levels, they need to be protected from contaminants. Certain impurities are common in the boiler feed water and makeup feeds. The contaminants include dissolved gases, silica, copper, iron, hardness, aluminum, magnesium, and calcium. Failure to get rid of these contaminants effectively leads to rising in problems like fouling of the boiler, corrosion, and scaling. These may necessitate costly repairs, inefficiency, and expensive maintenance.
How Do the Boiler Feed water Treatment Systems work?
The system works by eradicating impurities from the water. It also controls the conductivity and acidity of the water. The boiler feed
water treatment has the following salient steps:
i. Water intake – Circulation water in boilers can be lost through leaks, steam consumption and loss of condensate return. The makeup water used to replace the lost water is obtained from a variety of sources. There is great need to have this water treated before it is introduced into the circulatory system of the boiler. Otherwise, it will cause damage to the unit and its components.
ii. Filtration – A number of filtration units are used to filter the stream. The purpose of this is to clean the water of organic material, turbidity and
sediments. It is very effective in helping you avoid the excess maintenance cost associated with damage to downstream equipment.
iii. Softening – IX is very effective in combating boiler feed water
hardness. It effectively eradicates compounds like nitrates, chlorides,
sulfates, and bicarbonates.
iv. Dealkalization – Alkalinity is a major culprit when it comes to corrosion in piping and carryover and foaming in boilers. The boiler feed water, therefore,
needs to be subjected to a process that involves a strong anion IX and degasification. This process removes sulfates, bicarbonates, and nitrate ions, thus rendering both the piping and boiler safe.
v. Nanofiltration (NF) and Reverse Osmosis (RO) – The two treatment processes are very good at the removal of organics, bacteria, hardness, and silica. They both use semi-permeable membrane to trap large impurities but allow water molecules through.
vi. Primary Ion Exchange – Deionizers are more appropriate when it comes to either high-pressure boilers are large volumes of water. IX produces better results under these conditions.
vii. Deaeration or degasification – This is the removal of both oxygen and carbon dioxide from the water, in order to prevent corrosion. This process usually comes after all the other steps of treatment.
viii. Polishing – This step may be used after the primary IX or RO. Polishing involves electrodeionization (EDI), mixed bed deionization (DI) or offsite
ix. Routing – After the boiler feed water is adequately treated, the water is directed to the boiler where it is heated into steam. This is combined with
mixed with the treated makeup water.
The above industrial water filtration systems show the general guidelines of how the systems work. The unique makeup and chemistry of
each system are quite complex. There are varieties of technologies that interact with each system. An expert manufacturer of industrial water
purification systems is best placed to advice you on what is best for your facility.
A professional water treatment specialist has the expertise to undertake a through treatability study of your installation. They can then
determine the systems and technologies you need, based on your unique circumstances.
For queries regarding industrial water filtration systems do not hesitate to contact us at (866) 829-6460. You can also visit us at http://www.progressivewater.com.
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