MECO - A worldwide leader in water purification

MECO Multi-Media Filters are designed for the removal of suspended solids greater than 10 microns. The media filters are designed based on your effluent water quality required and the feed water analysis. Media filters can be provided individually or as part of a total water treatment solution. The control system for the media filter can be dedicated to the filter or part of a total water system. Filtration systems are designed specifically for your application using either fiberglass, PVC, lined carbon steel or stainless steel in the materials of construction.

Furthermore, each filter may be equipped with the MASTERedge™ Package, a system of features that provides even greater value. You also benefit from the expert and responsive service delivered through MECO's MASTERsupport™ service capabilities.

Under-Drain/Internals

One of the most important aspects of any filter system is the design of the internals and the associated supports. On MECO filters, you will find header lateral or hub radial distributors and collectors at the entrance and effluent of the vessel. The result is an efficient filter with a high degree of reliability and low maintenance.

Manifolded Valving & Piping Supports

A standard feature of MECO media filters, softeners and carbon filters is independent valving completely assembled, manifolded, supported and tested. As a result, you get a system that is highly reliable, as well as fast.

Stainless Steel Airlines

As part of the MASTERedge™ package on MECO pretreatment vessels, your system will be fitted with stainless steel airlines. While the plastic alternative is certainly easier to install, the stainless system is more robust and less susceptible to nicks and cracks resulting in improper valve operation.

Solenoid Panel

MECO filter vessels are completely preassembled and tested with all valves and air lines led to one central solenoid panel. You will find this system more organized, easier to troubleshoot and validate.

Reverse osmosis is used as pretreatment and final treatment steps in many biopharm water systems. Impurities present in the feed water to the reverse osmosis system can build up on the membrane surface and adversely affect performance. RO membranes see two modes of performance degredation due to these impurities: scaling and fouling. Proper pretreament is essential to maximize the performance and longevity of the RO system.

As scalants and foulants build up on the RO membrane surface, higher and higher feed pressure is required to maintain a constant output. The pressure drop across an array of RO elements is usually measured. This differential pressure is a good indicator of the amount of fouling occurring in the membrane array. The differential pressure is calculated by subtracting the RO membrane reject pressure from the feed pressure.

Most commercially available RO membranes have a maximum allowable differential pressure. Operation beyond this maximum differential pressure can result in serious mechanical damage to the membranes due to the large forces that are generated in the flow direction in the membrane. Each membrane sees a larger and larger force as the differential pressure builds towards the end of the array. The permeate tubes see the majority of this force and the last element sees the largest of all the forces created by the pressure drops of the upstream elements.

Differential Pressure Measurement

Cleaning RO Membranes

In order to return the membranes to their original operational levels of permeate flow and water quality, the membranes must be chemically cleaned. A low pH cleaner is used to remove mineral scale while a high pH cleaner is used to remove biofilm. Chemical cleaning a RO membrane is typically a lengthy manual procedure. At some point, the membranes may become permanently fouled and the production levels of the membrane cannot be restored to acceptable levels of production. The membranes must then be replaced to restore the performance of the RO system.

A major source of the fouling is the suspended solids contained in the RO feed water. The typical measurement of these suspended solids is turbidity expressed in nephelometric turbidity units, or NTU. This is a measure of the light scattered at a particular wavelength by a sample of the water. The higher the level of suspended solids present in the water, the higher the NTU reading.

In order to prolong the time between cleanings and the overall useful life of the RO membranes, it is necessary to pre-treat the RO feed water to remove the suspended solids. To be effective, the water produced from the RO pretreatment system must remove solids to such a degree that turbidity is no longer a viable method to measure the remaining solids present, i.e. the turbidity measurement is zero. At this point, the suspended solids are measured by observing the decrease in flow through a filter paper. The standard method for this measurement is the Silt Density Index or SDI.

Based on vendor literature, RO manufacturers specify an SDI of 3 or less as acceptable for feed to their membranes. Feed water with a higher SDI will result in a significantly lower lifetime for the membranes.

Scaling

Scaling occurs when soluble inorganic compounds in feed water concentrate and precipitate onto the membrane surface and form a scale. This scale can be very difficult to remove and treatment often depends on the type of scale that is on the membrane. Scale formation due to exceeding the solubility limits of these compounds is detrimental to RO system effectiveness and membrane life. Common inorganics that lead to scaling are Calcium Carbonate and Silica.

The feed water is often treated by methods such as acid injection, softening, or addition of a scale inhibitor to reduce or eliminate these scaling compounds. Another way to control scale formation is to reduce the system recovery. Higher recoveries may cause the precipitation of these inorganics due to increasing their concentration above the solubility limits in the concentrate stream. The system recovery can be reduced to bring this concentration below the solubility levels.

Fouling

Fouling may occur due to either colloids or biological growth … or both. Colloidal matter such as clay, colloidal silica, and dead microorganisms often lead to non-biological fouling. Measuring and calculating the Silt Density Index (SDI) can find the content of these colloids in source water. Pretreatment options that help reduce or eliminate colloidal matter in feed water are media filtration, coagulation-flocculation, cartridge filtration, microfiltration, or ultrafiltration.

Fouling due to biological growth on the membrane surface is known as biological fouling. With biological fouling, organisms such as bacteria, fungi, viruses, etc. collect on the membrane surface and form a living film under the correct conditions. Biofilms are very hard to clean due to the fact that the film on the membrane surface is often thick and thus provides a layer of protection for these microorganisms. These organisms feed on the deposited organic material located on the membrane surface and can quickly multiply, adversely effecting the membrane flux rates. This causes a rapid build up of differential pressure across the RO membrane array.

SDI

The SDI of a water is calculated by the following formula;

SDI 15 = [ 1 - T0/T15 ] * 100

where T0 is the time required to collect a specific volume of water (typically 500 mls) flowing through a .45 micron filter paper at 30 psig inlet pressure and T15 is the time required to collect the same specific volume after 15 minutes. The apparatus commonly used for collecting the SDI measurement is shown in figure 2.

Based on vendor literature, RO manufacturers specify an SDI of 3 or less as acceptable for feed to their membranes. Feed water with a higher SDI will result in a significantly lower lifetime for the membranes.

Q: Is a MMF necessary as feed to a RO unit?

A: Not necessarily. Most RO systems utilize a cartridge filter in the feed line. This filter has a micron rating range of 1-5 microns. The MMF will remove particles of a nominal 10-15 micron rating. Therefore, without the MMF, the cartridge filters will foul fairly quickley. The MMF also keeps suspended solids, from upsets in the system, from entering the other pretreatment vessels.

Q: Do I need a MMF as pretreatment to my Vapor Compression still?

A: There are two designs for Vapor Compression stills, Vertical Natural Circulation and Horizontal Spray Film. In the natural circulation design, which MECO utilizes, the orifice sizes are very large (3/8" to 5/8") and will not clogg from suspended solids. On the other hand, the spray film evaporator uses spray nozzles that have tiny openings which can and will become clogged with small particles.

The MECO Pretreatment Vessel MASTERedge Package™

More and more companies are turning to MECO for reliable and thorough pretreatment filtration. Here’s why:

Dynapore Mesh Screen

The under-drain system has a Dynapore Mesh screen over each lateral component. This screen does not allow media to flow out of the vessel to the downstream components; thus removing the requirement for filter cartridges after pretreatment vessels.

Bed Expansion

Freeboard design exceeds the bed expansion during the backwash process, which eliminates the loss of media.

Sanitization Options

Designed for sanitization with clean steam, hot water or the patented sanitization from a MECO Vapor Compression Still.

Solenoid Panel

A solenoid panel is located on each vessel for one central air line connection. Stainless Steel Airlines are connected to each individual valve. Standout Features Include:

• Galvanized rigid conduit
• Stainless Steel Airlines
• Conservative flux rates
• Mirror finish stainless steel cladding on all sanitizable designs

Anytime. Anywhere.

• 24 hours, 7 days a week access to effectively manage your water system.

Real Time Access to:

• Purchase spare parts online
• Track status of outstanding orders
• Review shipping information
• Review invoice/payment history
• Review online maintenance records
• Request technical information
• Online electronic manuals
• Remote system monitoring capabilities

   MECO understands the importance of providing our customers with the parts and services required to maintain systems operating at optimum capacity. Our online service center - MECO MASTERsupport™ is a good example of that. It enables you to monitor your system remotely, place orders, access service records and view your system's manuals when it's convenient for you. Anytime. Anywhere.

With a simple point and click, our entire parts inventory is available to you. Through the online service center, you also get real-time access to invoices, orders, shipping status, system manuals and service trip reports. Everything you need to know to effectively manage and maintain your treatment plant is right at your fingertips.

It's another example of MECO's commitment to providing the highest quality spare parts and cost effective support throughout the life-cycle of the product.

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