Tag Archives: Bag Filter

We’ve written several articles on the benefits of using bag filters in industrial water applications.

Three Benefits of Wastewater Filtration

Wastewater filtration is a prudent practice for industrial companies, as it eliminates contaminants and other harmful substances from water and allows for proper disposal of those contaminants. In addition to the savings from water costs, it also has environmental implications, including reducing pollutant emissions. This reduction of pollution protects water supplies and other natural resources. Industrial plants across the country can benefit from flexible wastewater filtration solutions to make their commercial maintenance more efficient, and the following benefits are a direct result of applying an effective wastewater treatment solution.

Save On Expenses

In the past, companies could simply dump their waste into the nearest body of water.  Times have changed, and in many cases today simply disposing of untreated wastewater either into a water source or down the drain will incur heavy fines. By utilizing wastewater treatment solutions, this water can be reused, reducing your average expenses and transforming your wastewater into a money-saving asset instead of a burden. Also, fully automated solutions, like our STiR filter, reduce labor and decrease disposal costs to increase your bottom line.

Environmental Factors

Environmentally concious wastewater systems ensure that your company remains compliant with all relevant pollution laws, and does not harm the environment. By repurposing tainted water and turning it into something of value to your company, you remove the need for long distance transport and other wasted actions. Instead, you convert wastewater into a useful resource. These wastewater treatment systems also reduce your water consumption and discharge and produce minimal emissions compared to other systems.

Flexible Systems

Wastewater filtration provides flexible systems for water purification. As burgeoning technologies become available, you can integrate new solutions into your wastewater treatment systems to improve efficiency. Wastewater filtration is a scalable resource for commercial applications, which maximizes cost savings and maintains environmental compliance over time.

For more information on integrating a wastewater filtration system into your commercial business, contact us today, and stay tuned to our blog for in-depth articles on industrial filtration solutions.

Types of Industrial Water Treatment Equipment

Industrial water treatment equipment comes in a variety of implementations, all designed to suit particular operating needs. Filter presses, bed filters, cartridge filters and bag filters all excel in their intended applications. We’ll look at each type of filter and examine what applications it is most appropriate for below.

Filter Presses

Where most industrial water treatment equipment is designed to remove solid material from water, filter presses are designed to remove water from the solids. Filter presses are ideal for any filtration application where enough material needs to be removed so that more conventional filtration methods would be ineffective. A filter press operates, as the name implies, by exerting physical pressure usually in the form of either air or a water-filled diaphragm on a slurry mixture and extracting the moisture. The remaining cake of material is then disposed of.

Bed Filters

Bed Filters are filters with a bed of material (typically crushed walnut shell, sand, anthracite or activated carbon) that removes contaminants. Material is collected throughout the depth of the bed, allowing large amounts of material to be collected before a backwash cycle is initiated. Inlet water pumps through the filtration medium, which collects and suspends contaminants. Once the medium is saturated with contaminants, a backwash cycle is initiated. The filtration medium is fluidized and washed. This industrial water filtration method cleans the medium and readies the filter for use. This reuse of the filtration medium minimizes waste associated with the process.

Cartridge Filters

Cartridge filters are disposable, replaceable, self-contained filtration units. They consist of a central perforated core wrapped in layers of filtration material. Inlet water is pumped in through the top of the filter core, and passes through the walls of the filter. Contaminants can be caught throught the depth of the filter cartrige, which allows individual cartridges to achieve very high filtration efficiencies. Cartridge filters are typically used where high purity water is required.

Bag Filters

Bag filters are similar to cartridge filters in that they are also disposable and replaceable. Bag filters are shaped like a large sock, and are sometimes called sock filters or filter pots. They catch contaminants on the surface of the bag, and are typically used as a low cost option to remove particulate from wastewater streams.

Bag Filter Magnetic Inserts

The buildup of ferrous material poses a serious risk to not only coolant filtration systems, but to the quality of products produced by a manufacturer.  This unwanted material can damage cutting tools and compromise the quality of finished parts.  Many companies in a variety of industries turn to bag filter systems to help eliminate this material from their operations.  While bag filters are a great first step in combatting this problem, magnetic inserts offer significant benefits to companies that use bag filters in their factories.

Magnetic Inserts & Improved Performance

Magnetic inserts can improve the lifespan and effectiveness of bag filters.  A typical bag filter system would use just the bags to remove material from the coolant.  Unfortunately, bags have a limit to the size of particles they can remove (bags that are sized too tightly will remove important coolant additives in addition to waste).  On the other hand, magnetic bars do not suffer from this deficiency.  These bars are able to remove magnetic particles that would otherwise pass through the pores of bags.  To remove even the smallest particles, flow should be limited so that the fluid has the greatest possible contact time with the magnets.  To maximize fluid contact time, the system should always operate with a laminar flow.

Less Maintenance & Longer Lifespan

Bag filter systems that do not take advantage of magnetic bars solely rely on the bag to filter out ferrous material.  Naturally, bags that have reached the end of their useful life have to be replaced by plant personnel to complete the changeover.  Magnetic inserts increase the longevity of the bags by removing particulate before it even contacts the bag.  As a result, bags last longer, which directly translates to fewer man-hours that will be spent changing bags.

Cleaning the magnets is itself simple as well.  When bags eventually plug, simply removing the magnet from its frame and wiping it off is all that’s needed to properly maintain them.  Our magnets have a useful life that is practically endless, meaning that they do not need to be replaced over the life of the product.

Advantages Of Walnut Shell Media

Our Walnut Shell Media Filter has a variety of advantages over other options in the industrial filtration space, especially when filtering oil and total suspended solids (TSS).  Because it is a backwashing filter, Walnut Shell Filters not only are much better filters, but are more efficient in many processes.

  • Hydrocyclones are often used for removing oil from water, but will not fully polish the water.  For example, oil droplets smaller than 20 micron are typically not removed by hydrocyclones.
  • Cartridges and bags are also frequently used, but must be disposed of.  Maintenance personnel are also required to change the filter media when it becomes plugged.  Increasing restrictions on disposal in certain industries have also led to skyrocketing disposal costs.

How Backwashing Filters Work

When compared to hydrocyclones and disposable media filters, backwashing deep bed filters have many distinct advantages.  Contaminants are captured by a granular media bed and then removed by an efficient tortuous path through the media bed.  After the bed becomes full of contaminants, it is then backwashed, which cleans the bed without incurring media disposal costs.  For the filter to operate at a high efficiency over a long period of time, all contaminants from the bed must be removed during the backwash.

Better Filtration

One of the advantages of walnut shell media is its superior filtration of wastewater.  For example, Walnut Shell Filters will typically remove 95% of solids at 5 micron, and 90% of suspended oil.  Walnut shells have a natural affinity for oil, causing it to bond to the surface of the media.  Unlike in sand filters, whose captured oil films over the surface, captured oil remains as droplets.  These absorbed droplets will then contact smaller droplets, which coalesce onto the larger droplets and increase the removal rate of small particles over time.  That’s why black walnut shells have an oil absorption capacity that is 2-3 times that of sand.

Improved Efficiency

One of Filtra-Systems’ goals is to provide industrial filtration solutions that can improve a company’s operations in multiple domains.  Systems that require less maintenance not only help reduce upkeep costs, they also help to ensure that needless interruptions of operations that can have a negative impact on a company’s bottom line do not occur.  That’s why our Walnut Shell Filters have beds that don’t require replacement for the entirety of the product’s life.  Because walnut shells are preferentially wetted by water, oil is easily scrubbed from the shells during a backwash.  Black walnut shells (as opposed to English) have a high modulus of elasticity, which explains why the beds don’t need to be replaced.  The expected yearly attrition rate is 2%, which is much lower than English walnut shells, pecan shells, and other types of media.

Likewise, these filtering systems need less floor space in the factory to operate, freeing up room for different machinery.  Walnut shell filters are typically sized at 10-12 gpm/ft2, which is a greater flux than completing media filters.  The higher flux means smaller filter housings can be used, which is what specifically translates to more floor space for customers.

Less water required to regenerate the bed is another benefit customers enjoy.  The flux required for fluidization of the bed is only 4.5 gpm/ft2 (based on a clean media bed, oil and solid saturation will increase this requirement), which is significantly lower than competing technologies.

Known Issues Of Sand Filters

To those who have had the misfortune of operating a sand filter, no explanation is needed for the colloquial term “mudball.”  To the uninitiated, mudballs form when sand filters are exposed to oil that results in an oil film across the sand.  this film prematurely clogs the filter, drastically reducing the system’s efficiency.  The plugged bed has a decreased filtration area, and will backwash more frequently.  Even after a backwash, the bed remains unclean because the backwash water does not penetrate the film, and channels around the mudballs.  As the problem persists the bed will inevitably need to be replaced, a manual operation that requires personnel to dig out the clogged bed.  This adds to unnecessary costs, both in paying trained personnel, as well as system downtime.

Which leads us to pricey filter replacement and disposal.  Generally, sand filter beds need to be replaced every five years.  However, with regular exposure to oil, replacement time can be reduced to as frequently as every six months.  An alternative to filter replacement is to clean the filter bed, a procedure that involves soaking the bed with a condensate, or a light oil.  The time consuming nature of this process means that sand filter users typically choose to replace the bed instead.  Sand is also an OSHA dusting hazard, and handling sand to replace the bed can result in exposure to plant personnel.

Sand filters typically use an air scour to remove oil and solids from the media bed.  Drawbacks to this technology include:

  • Incomplete fluidization of the media bed
  • Extra piping and valves required upon installation
  • Larger compressor and air regulator are needed
  • Possible installation of a vapor recovery and processing unit (VRU)

The compressed gas needed for this operation may also change the electrical classification of the area to Class 1, Div 1, increasing electrical costs for all process equipment nearby.

The backwash volume required for sand filters can be up to 5 times more than walnut shell filters.  Sand filters are designed at 6 gpm/ft2, and the flux required for fluidization of the bed is 12 gpm/ft2 (based on a clean media bed, oil and solid saturation will increase this requirement).

Known Issues Of Anthracite

Another common media filter is anthracite.  Anthracite filters usually have three layers of differently sized media: a top layer collects coarse contaminants, the second layer collects smaller particulate, and the third layer is the final polish.  Unfortunately, substantially more water is needed to clean anthracite filters.  This is because the backwashing process requires a subsurface wash to break up any waste before the standard backwash.  In fact, an anthracite filter may require seven times more water to backwash than a comparable walnut shell filter!

Additionally, upset conditions can cause the media to mudball.  The attrition rate for anthracite is much higher than walnut shells, and the media generally needs to be replaced every year.  Anthracite filters are designed with a flux of 4-4.5 gpm/ft2.

Filtration Design Flux

Backwash Fluidization Flux

Backwash Volume (compared to WSF)

Walnut Shell Filter

12 gpm/sqft

4.5 gpm/sqft

1X

Sand Filter

6 gpm/sqft

12 gpm/sqft

5X

Anthracite Filter

4 gpm/sqft

N/A

7X

ChangAN Ford Sigma Fox Engine Program – Central Coolant & Chip Handling Systems

ChangAN Ford purchased Central Coolant Systems & Chip Handling Systems for the Block Honing and Crank Machining and Grinding departments which produce I4 Sigma and I3 Fox Engines at its Chongquing, China manufacturing facility.

Filtra-Systems Company was selected by ChangAN Ford because of its expertise in providing multiple, full engine assembly production lines with custom engineered filtration and chip handling systems.  Past Filtra-Systems designed systems used in engine assembly line projects showed capabilities of being able to support a 20 year expected life cycle, which is expected to amount to 8 million engines.  This reputation of quality and experience was a major factor ChangAN Ford was looking for when awarding the project.  Filtra-Systems Company is also ISO 9002 certified.

The scope of supply consisted of the following:

For the Block Honing application for Sigma and Fox:
+++– One (1) Hydro-Vac Filtration System
++++++– Model HV-4D
++++++– Complete with two (2) 17-Bag Filters
++++++– Services 8 CNC Machines
++++++– Coolant flow rate of 100 m3/hr
+++– One (1) Hydro-Vac Filtration System
++++++– Model HV-4D
++++++– Complete with two (2) 8-Bag Filters
++++++– Services 4 CNC Machines
++++++– Coolant flow rate of 55 m3/hr
+++– Two (2) Magne-Tight FSMB-1.5 Magnetic Separator
+++– Five (5) Chip Handling Dumping Stations
+++– Nine (9) Chip Handling Carts (Dump Station compatible)
+++– Seven (7) Chip Handling Gondolas
+++– Temperature Control of Coolant
+++– Supply & Return Piping

For the Crank Machining & Grinding application:
+++– One (1) Double Hydro-Vac Filtration System
++++++– HV-6D
++++++– Complete with two (2) 23-Bag Filters
++++++– Services 24 CNC Machines
++++++– Coolant flow rate of 750 m3/hr
+++– One (1) Magne-Tight FSMB-10W Magnetic Separator
+++– Two (2) Chip Handling Dumping Stations
+++– Nine (9) Chip Handling Carts (Dump Station compatible)
+++– Seven (7) Chip Handling Gondolas
+++– Temperature Control of Coolant
+++– Supply & Return Piping

Filtra-Systems was able to deliver these systems as scheduled by utilizing both manufacturing centers located near Nashville, Tennessee (USA) and Suzhou, China.

Filtration training and service support was also provided to ChangAN Ford.  Dual language service and maintenance manuals were provided to the plant.

Filtra-Systems offices in Suzhou allow for convenient support for this facility, and will continue to provide filtration systems to companies in China, India and Asia.