Tag Archives: Anthracite Filter

Peruse our collection of articles on the benefits and drawbacks of Anthracite Filters.

The Best Replacement Technology for a Sand Filter – Filtra-System’s Advanced Filtration Technology

Filtra-Systems has over 30 years of experience in providing quality industrial water filtration solutions for various industries. Our company understands the detailed processes associated with sand filters including slow and rapid filtration options. We serve several different industries that have varying levels of filtration needs while working to conserve energy and water usage. Using walnut shell filters as a replacement technology for sand filters is an important option more industries are exploring. It is a matter of understanding the advantages and how your company or industry benefits from this unique technology.  CLICK HERE TO LEARN MORE ABOUT THE STiR FILTER PRODUCT. This link can be followed to learn more about a project that involved the STiR successfully replacing failing sand filters.

Filtra-Systems Understands Common Issues Associated with Sand Filters

Filtra-Systems has discovered a number of problems associated with traditional sand filters. Our company understands issues related to sand filtration and how these problems can lead to inefficiency within filtration systems. For example, the introduction of oil into a sand filter will cause portions of the bed to become clogged and uncleanable, even in extended backwash cycles. This leads to increased treatment and disposal costs, and potentially unsafe and unclean water. Because sand filter beds need to be replaced every few years, a replacement technology for sand filters can provide the best treatment process available for your operation. Walnut shell filters can help your company meet its goals, whether it is by reducing the cost of replacing the bed or by achieving lower backwash volumes.

A Wide Range of Industrial Water Purification Solutions

Advancements in filtration technologies allow industries to achive even greater flexibility with sand filters than ever before. Filtra-Systems specializes in technology that works to separate unwanted contaminants from water including oil and suspended solids. Our company provides unique, custom-engineered systems including pressure and vacuum walnut shell filters, bag filters, and cartridge filters. These technologies follow precise specifications to timprove water quality.

Determining the Best Industrial Water Filtration for Effective Results

Updating your existing sand filters to walnut shell filters can result in numerous benefits to your facility. Efficient oil-based contaminant removal can be achieved by using walnut shell media, as opposed to sand, which tends to blind and “mudball” portions of the bed. This is a prime example of how our technology can help improve water usage, cut operating costs, and improve the flow of water. Solutions offered as a replacement for sand filters are patented and incorporated through detailed cycles with limited use of chemical compounds. Replacement technologies such as the STiR Walnut Shell Filter overcome the limits of sand filters in several important ways. These include higher removal efficiencies, especially of oils and greases. The walnut shell media in the STiR also never needs to be replaced. The bed of a sand filter typically needs to be replaced every 3-5 years. Contact Filtra-Systems today to learn more about the STiR!

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.

Advantages Of Walnut Shell Media

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

  • 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 For You

When compared to hydrocyclones and disposable media filters, backwashing deep bed filters have these 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 huge 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 your company’s bottom line do not occur.

That’s why our Walnut Shell Filters media beds don’t require replacement for the entirety of the product’s life.  Because walnut shells are preferentially wetted by water, oil is easily rinsed from the shells during a backwash.

Black walnut shells (as opposed to English) have a high modulus of elasticity, which explains why the beds won’t need to be replaced.  The expected yearly attrition rate is only about 2%, which is much lower than English walnut shells, pecan shells, and other types of media.

And better yet, these filtering systems need less floor space to operate, freeing up room for other machinery.

By the way, walnut shell filters are typically sized at 10-12 gpm/ft2, which is a greater flux than competing media filters.  The higher flux means smaller filter housings can be used, which translates to more floor space.

The fact is, less water required to regenerate the bed is another benefit you’ll 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 Frustrations 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.

Unfortunatly, 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 hand dig out the clogged bed.  This adds to unnecessary costs, both in paying trained personnel and expensive system downtime.

Is pricey filter replacement and disposal costing you a time and money? 

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 Concerns 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.  Why?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