Filtersafe’s Smartweave Screen: Water Filtration at a Whole New Level

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Most eCommerce clicks not only put new clothes or appliances in your virtual shopping cart, they also are putting your packages on cargo ships for delivery. The continued dependence on online shopping has meant more work for  international shipping vessels, which are constantly moving from one corner of the globe to another – and they’re discharging ballast water in every port they visit.

This can be dangerous for our oceans, as zooplankton, phytoplankton, and other microorganisms that hitch a ride in ballast tanks can damage the native ecosystems if they are deposited into a new body of water. Therefore, it is essential that ships filter their ballast water before releasing it back into the sea.

As a company founded by engineers, Filtersafe has been dedicated to finding innovative solutions to filtering sea water. The current seawater screens often suffer two main problems: blockage, which can result in pressure depressions and a decreased flow rate, and an inability to filter out smaller microorganisms.

To address these issues, the Filtersafe engineers created the Smartweave screen. This unique technology is a weave-wire screen specifically designed to tackle the challenge of seawater filtration. By using a combination of weave wire filtration screens, protective screens, and a reinforcement layer — as well as the automated cleaning power of our Everclear system — this innovative, highly effective screen filters out sediment and microorganisms, protecting native marine life in every port. Its combined efficacy and durability make the Smartweave screen a filtering element ships can rely on for years.

 

How It’s Made

Filtersafe understands the unique challenges facing ballast water filtration (one of the most challenging seawater applications). Seawater contains microscopic particles that can cause harm when transferred to other ecosystems and encourage the creation of corrosion within the ships’ interior. Filtering out elements this small requires a complex and multi-layered system, so the Smartweave designers created exactly that.

The Smartweave screen is made up of three stainless steel weave-wire screens and a fourth reinforcement layer to enhance the screen’s integrity. This includes one filtration control layer, two protective layers on either side, and one reinforcement layer. We then take this combination of screens and sinter them together, creating one mega-screen that is durable enough to filter without additional support.

These screens are available in a variety of sizes, from 500 microns down to 10. This allows ship owners to choose a Smartweave screen that best suits their vessels’ unique needs. The Smartweave seawater screen is also made from 904L stainless steel: an stainless steel that offers high corrosion resistance, higher quality, and a longer-lasting screen than the standard 316L stainless steel and other options in the market today.

The innovation and careful design work behind Smartweave have made it one of the top weave-wire screens for seawater filtration today. This screen offers enhanced strength and top performance, so shippers can trust that their ballast water is safe to discharge and is compliant with the IMO G8 requirements.

 

How Does It Work?

All the innovation in the world doesn’t matter if a product doesn’t work. The engineers at Filtersafe know how important seawater filtration is, and so they’ve spent years testing and perfecting the Smartweave screen. As a result, Smartweave is one of the most effective filtration systems available today, keeping zooplankton, phytoplankton, and sediment out of ballast water across the world.

The term “zooplankton” refers to small microorganism and the immature stages of larger species. It is vital to filter these from ballast water, as they can be detrimental to the native ecosystem at a port of call. According to tests from Filtersafe and other research groups, the Smartweave screen removes 99.95% of zooplankton from ballast water – more than any other filter available today.

Shippers also need to filter phytoplankton from their ballast water before releasing it into the sea. Phytoplankton, or microscopic marine algae, are an important food source in the ocean’s ecosystems – but only if they’re in the right location. While phytoplankton can be very small (as small as 10 microns), Smartweave is an effective filter for them, too. that the Smartweave screen removes 100% of phytoplankton larger than the micron of your selected screen.

Finally, a filter must be able remove sediment and other suspended solids from any ballast water. Once again, Smartweave delivers here:  A series of tests we conducted on our filter show that even in extreme conditions when the TSS levels reached 2500 ppm, we were able to decrease the decrease suspended solids from 2500 ppm to 100 ppm – a removal rate of 98%.

 

Constantly Improving

Today, Filtersafe treats 25% of the world’s ballast water – and all because of unique, innovative, and effective products like the Smartweave screen. For some teams, the Smartweave screen’s impressive filtration rates would be enough to call the filter a success. But Filtersafe is dedicated to making the ballast water filter even better.

The team is constantly innovating and perfecting our ballast water treatment systems. We’ve outfitted our Smartweave screens with our Everclear cleaning sequence, which automatically returns your filter to its original operating parameters. This ensures peak performance and an optimum flow rate – and provides the user with peace of mind.

Each Smartweave screen is used in conjunction with Filtersafe’s patented nozzles – the Nozzlex system. This uses suction technology to clean the screen thoroughly and completely with each use(without damaging it). These features help maintain the Smartweave’s exceptional performance, so captains can focus on their cargo and getting to their next location and not just about meeting USCG or IMO water treatment standards.

*Efficacy is dependent on the size and distribution of the TSS.

Sizing Up BWTS Filter Options To Reduce Operational Compliance Risk

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In a recent panel discussion for Riviera’s Ballast Water Webinar Week, Dr. Guillaume Drillet, Regional Manager at SGS, shared his views on the main reason for ballast water treatment system (BWTS) failures during compliance testing. Speaking on the webinar titled “BWMS commissioning testing: making it work in practice”, he said that organisms over 50 microns in size are responsible for clogging BWTS, subsequently leading to test failure.

His comments underline the critical importance of BWTS filters – the component responsible for preventing organisms from entering the tanks. Without a strong and robust filter, the effectiveness of the entire BWTS could be compromised, leaving manufacturers open to criticism from ship owners and operators, who must repeat unsatisfactory tests at a later date.

 

Compliance challenges

Selecting the right filter brings significant rewards to the shipping industry, from driving compliance, to preserving marine biodiversity and increasing operational efficiency.

Each BWTS and vessel is unique and faces its own set of challenges and specific stresses. These are impacted by the BWTS used and the conditions it must operate in. For example, there are challenging testing conditions in shipyards with poor water quality, shallow harbors with a high silt load, and difficult initial loading conditions. If a filter is unable to withstand these conditions and clogs, water flow through the BWTS will be limited or even prohibited.

 

Regulation requirements

Under IMO G8 requirements, filters must prove their ability to perform effectively in water with total suspended solids (TSS) up to 50 mg/liter. However, the threshold to pass this test is not reflective of water quality standards in some key maritime locations. For example, TSS in the Ports of Shanghai and Hamburg are twenty times higher than IMO G8 requirements for BWTS type-approval testing. This means high-quality filters that exceed IMO performance standards are critical.

Fortunately, filter performance in more challenging marine environments can be tested through the Control Union Shanghai filter test (Procedure CUW-HBR-P-2), which uses proxy mud up to and beyond 1,000 mg/L to test filter performance.


Size is part of the solution

In order to prevent organisms over a certain size from impacting BWTS and compliance testing, filters need to be engineered with a design that has effective mesh sizes.

Filtersafe use mesh sizes from 10 microns upwards, at flow rates from 50-5000m³/hr in a single unit. Using these fine mesh sizes ensures the system prevents organisms from entering or impacting the system by settling into the ballast tanks or clogging the system.

A filter capable of withstanding the highest TSS conditions found in the world’s oceans will provide confidence to shipowners that the BWTS will pass compliance tests in any port around the world. In its Shanghai Test, which simulates an excessively high particle load, Filtersafe filters did not clog, even when the test reached 2,500 TSS.

With compliance testing coming ever more to the fore, BWTS manufacturers, shipowners, and operators need to be confident that systems are capable of performing effectively throughout the lifecycle of the vessel across all marine environments, including areas where water quality challenges are acute. It is important to remember – mesh size matters.

How well does Cathodic Protection negate corrosion when used in Seawater Filtration?

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Ballast water filters need to withstand the most challenging circumstances in seawater filtration. Why is Cathodic protection considered the industry standard for corrosion prevention, and is it the most effective solution available?

A recent report made public by the U.S. Maritime Administration stipulates that, as of January 1st, 2015, there were 41,674 ocean freight merchant vessels (weighing in at 1,000 gross tons and over) registered with an International Maritime Organization number and sailing through waterways across the globe. Among the ships in this worldwide fleet are vessels ranging from container and general cargo ships to tanker ships. While these ships run the gamut with respect to size and functionality, they all share a single and particularly significant vulnerability. They all run the risk of falling prey to corrosion-related degradation of their ballast water filters due to the various corrosion challenges facing ballast filtration systems. Taking in seawater for ballast naturally invites a host of microorganisms that ballast water filters need to treat, such as Sulphate-reducing bacteria and phytoplankton, which stimulate microbiologically influenced corrosion (MIC). The filters not only need to protect the ballast water tanks from MIC, but they are also subject to rust themselves and need adequate protection against it. After several challenging years focused on securing regulatory compliance under the Ballast Water Management Convention (BWMC) and U.S. Coast Guard’s Final Rule for ballast water treatment, shipping’s priority has shifted to operational compliance, which ensures BWMS are compliant for the lifecycle of the vessel. At the Marine Environment Protection Committee (MEPC) 75th session, the International Maritime Organization (IMO) issued guidance to Administrations that all BWMS installations should be tested following commissioning. This requirement, as well as guidance previously issued by individual flag administrations, has provided the first glimpse into the real-world performance of ballast water management systems after installation. One of the main reasons for BWT failures during compliance testing is organisms over 50 microns, which clog the system. This can be prevented by a strong and robust filter. Without it, the effectiveness of the entire BWTS could be compromised, leaving manufacturers open to criticism from ship owners and operators, who must repeat unsatisfactory tests at a later date. In an ideal situation, to ensure uninterrupted operation and protect BWTS, the recommended practice of leaving the ballast water filters full at all times or emptying and drying them would help prevent corrosion and its subsequent degradation from taking root. However, the need to take on more ballast water to accommodate the absence of cargo during particular portions of a given voyage and unexpected rough operational conditions during loading and unloading procedures often makes it difficult to successfully and satisfactorily complete the process on a thorough and regular basis. The result: sedimentation accumulates on the ballast water filters, leading to reduced service life, the risk of failures, and high, short- and long-term maintenance costs. To ensure uninterrupted operation regardless of varying water conditions and other unpredictable factors, ship owners need effective and dependable filtration systems that protect their entire ballast water management systems. The filters remove as much matter from the water as possible before it goes on to secondary treatment, reducing the amount of chemicals needed and time required to neutralize living organisms in the water. If the filters themselves are not adequately protected from corrosion, they might not filter water effectively, incurring frequent maintenance and replacement costs.

Cathodic Protection for Ballast Water Filters in Seawater Applications

Today, most ballast water filter screens in the world are made of 316L stainless steel. Cathodic protection is the most common corrosion protection method for this type of steel, making it widely used in vessels worldwide. Cathodic protection safeguards the metal against corrosion by connecting the at-risk steel to a highly active “sacrificial metal” acting as an anode. The anode introduces free electrons to the space and relinquishes its ions. In doing so, the formerly active 316L steel areas on the screen’s metal surface become passive, and the new, more active metal coating ultimately and safely corrodes instead. While Cathodic protection has long been recommended by filter and screen manufacturers to provide the necessary protection for ballast water screens made of 316L steel, this corrosion protection approach has some significant drawbacks. A sacrificial anode can be used for protecting the filter’s screen, but the anode is consumable, and its dissolving leads to the formation of a hard scale on the screen surface. This scale is caused by the buildup of calcium carbonate and results in clogging of the screen pores. In high consumption rates of the anode, this becomes a critical risk and requires regular cleaning of the screen. The economy of Cathodic protection is less-than-ideal. Although it is cheaper than other alternatives, installing Cathodic protection is complicated. Once it is up and running, ongoing electricity supply and periodic inspection and maintenance fees add to the cost. While Cathodic protection is a viable solution, its durability may call its high investment requirements into question. In particular, the sacrificial anodes’ limited available current and their vulnerability toward rapid corrosion lead to a shockingly limited lifespan. Furthermore, sacrificial anodes need to be immersed in an electrolyte for a minimum of 24 hours before Cathodic protection can be applied. If filters are not regularly kept full as recommended by manufacturers, the sacrificial anodes need to be immersed for 25% of the voyage. With such downsides to Cathodic protection, it would only be natural to ask: Are better options available?

Alternatives to Cathodic Protection

One of the best alternatives to Cathodic protection is using a higher grade stainless steel for ballast water filtration. For example, 904L steel eliminates the need for Cathodic protection altogether. Traditionally used in the high-technology, aerospace, and chemical industries, 904L is also famously utilized in Rolex’s luxury watches. It has been chosen by luxury watch manufacturers thanks to its higher polish and water-corrosion resistance, enabling wearers to go about their daily business wearing the high-ticket accessory worry-free. Austenitic stainless steel 904L has a higher percentage of nickel and chromium than 316L steel, in addition to copper. Its composition provides it with superior corrosion resistance capabilities, rendering Cathodic protection unnecessary. Indeed, 316L steel is the traditional staple coating historically relied on by the ballast water market, and as such, it is regularly produced and widely available. But while 904L is less common, it is still relatively available, and can be supplied with excellent lead time. Though the initial cost of 904L steel is higher than that of 316L steel, due diligence processes have found that the benefits of applying 904L steel for ship ballast filters in seawater applications far outweigh the costs. The higher durability requires less maintenance and extends the lifespan of screens and filters, ultimately saving the industry precious stakeholders’ time and money in the long-term. If better corrosion resistance can be obtained by upgrading the steel, the traditional choice of 316L steel for ballast water screens, which necessitates Cathodic protection, needs to be re-evaluated.

Bottom line

Using Cathodic protection to prevent corrosion of ballast water filter screens made of 316L steel requires more frequent maintenance and part replacements, leading to increasing costs over time. The sacrificial anodes used in Cathodic protection stimulate the formation of scale, which clogs the screens. Installation of Cathodic protection is complicated, and the anodes need to be immersed in an electrolyte for a significant portion of the voyage. Overall, Cathodic protection is complicated to install and is a less durable corrosion prevention approach than other existing solutions available in the market today, such as using a higher grade stainless steel. Several parameters have been used to evaluate corrosion prevention approaches for ballast water filtration systems, including Pitting Resistance Equivalent Number (PREN), Pitting Resistance Accelerated Test, corrosion rates in acidic conditions, and natural seawater tests. A new comparative analysis of corrosion resistance approaches is now available for download in a special free white paper.   Download it now: Overcoming Corrosion of Stainless Steel Screens in Seawater Applications.