MECO - A worldwide leader in water purification

 

Lightweight Water Purifier

The Water Purification Answer for Today's Military.

The MECO Light Weight Purifier (LWP) is a highly mobile unit that can be used in support of low-intensity combat operations, nation building, civil affairs actions, peacekeeping, and disaster relief operations.

With the LWP, you’ll always get fresh water, no matter the nature of the contamination. The LWP can purify water that has been contaminated by nuclear, biological or chemical agents. Seawater and brackish water are no problem, either.

Not only is the LWP highly mobile; it’s easy to use. It can be set up and operated by a single soldier in 45 minutes or less.

As today’s military operates through smaller and more mobile units, these lighter more mobile systems will be critical in meeting the sustainment needs of these formations.


The Lightweight Water Purifier (LWP) System is intended to improve the responsiveness of water support to early entry, highly mobile forces throughout the spectrum of conflict in peace and war. It also provides quality water support to small units and detachments where distribution of bulk water is not feasible or practical. The LWP provides this water support without committing larger water production assets from the logistics support structure. The system tailors water production flow rates to the demands of independent Special Operations Forces, detachments and units typically engaged in remote site missions.

Notable Features of the Unit Include:

  • Designed to be man-portable and modular.
  • Transportable in HMMWV and medium tactical helicopter. Also can be air-dropped
  • Treats any water source including seawater, brackish, turbid, and NBC-contaminanted sources.
  • Uses Reverse Osmosis (RO) and Ultrafiltration (UF) technology.
  • Five modules: UF, high-pressure pump, control module, RO element, and chemical injection/cleaning.

Lightweight Water Purifier Field Setup

  • Automated, backwash cycles every 15 minutes, 30 seconds each UF cartridge.
  • Treats raw water to 60,000 milligrams per Liter (mg/L).
  • Produces 125 Gallons per Hour (GPH) from freshwater and 75 GPH from saltwater 45,000 mg/L.
  • Uses titanium pressure vessels for RO membranes.
  • Uses chemical injection pumps for coagulant or sodium bisulfite, antiscalant, and hypochlorite.
  • Overall power requirements are 240 volts/60 Hertz and 120 volts/60 Hertz.

The LWP technology enables the system to treat any water - anytime. The system utilizes membrane-based filtration which removes suspended solids from water as it passes through a porous membrane (which is classified by its pore size). Microfiltration and ultrafiltration membranes are effective for the removal of suspended solids and some high molecular weight dissolved solids.

Microfiltration

Microfiltration employs the use of a porous fiber that filters out most unwanted constituents in feed water. There are several types of microfiltration membranes, such as hollow fiber membranes and spiral wound membranes. These membranes have pore sizes in the range of 0.1 to 1.0 microns.

As an example, a spiral-wound membrane consists of flat sheets wrapped in a spiral configuration similar to a reverse osmosis membrane. The pores in a hollow fiber membrane or spiral wound membrane should be consistently on the order of 0.1 to 0.2 µm in size.

The Purpose of Microfiltration
Microfiltration provides the end user with the ability to consistently and efficiently remove suspended solids, bacteria, yeast, many viruses, and harmful biological contaminants such as Giardia Lamblia and Cryptosporidium from feed water. Typical fiber material is dependant on the manufacturer and application, but can be commonly found in PVDF (Polyvinylidenefluoride), Polyacrylonitrile or Polyethylene. Material choice can be dictated by the Molecular Weight Cutoff of the membrane material. A membrane containing a smaller MWCO provides better overall filtration.

Microfiltration Applications
There are a multitude of applications for microfiltration, ranging from pretreatment for the offshore industry to the pharmaceutical industry. This filtration method is commonly used at municipal drinking and wastewater treatment plants as both a pretreatment and polishing mechanism.

A Cost Effective Solution
Microfiltration can be very cost effective in comparison to multi-media and cartridge filtration systems. That's because microfiltration provides the ability to regularly clean the membrane and continue service for much longer periods of time. Filter cartridges typically must be replaced often depending on the level of suspended solids, and do not provide the level of filtration equal to microfiltration. This lack of filtration can lead to more frequent downstream equipment maintenance due to faster foulant build-up.

A Closer Look at a Microfiltration System
A typical microfiltration system consists of a skid frame containing racks that can hold several membranes with valves and instruments to help monitor system properties such as pressure, flow, and backwash frequency. Typical feed pressures for ultrafiltration systems are from 30 to 50 psi. Filtration can occur in one of two ways with a hollow fiber membrane: outside to in, or inside to out. Ultrafiltration systems are usually operated in a cross flow mode so that a small amount of concentrated dirty water is continually sent to waste.

The total amount of filtrate (filtered water) that the membrane makes each day per square foot of membrane surface area is know as flux. Flux is measured in gallons of filtrate per square foot of membrane surface per day. Membrane manufacturers have a ceiling value for the acceptable flux range of any certain element.

Flushing and Backwashing
While a microfiltration system is in operation, it is often flushed and backwashed to remove deposits from the fiber surfaces. However, the system will eventually need to be cleaned to caked solids that flushing and backwashing can no longer remove. This returns the system to its most effective level performance.

The main parameter used to show the effectivity and operational cleanliness of a system is transmembrane pressure, or TMP. When this pressure rises to 30 psi or higher, the suspended solids and other impurities in the water have "caked" on the membrane surface. The loss in pressure as the water moves across the membrane surface exemplifies the level of this caked material. The pores in the membrane wall are effectively clogged and filtrate flow is drastically reduced when the TMP has risen to the upper end of the allowable range.

At this point, the unit can be backwashed with permeate for a specified amount of time and at a particular flow rate. This basically works in reverse of the normal flow path and forces filtrate at a higher flow rate back through the pores, dislodging the cake on the membrane surface. The resulting freed particulate is sent to drain.

To further aid in cleaning the membrane surface, a pressurized air scour can also be utilized to help dislodge additional caked-on material. Low-pressure air is injected into the feed flow at the normal flow rate. The air helps to agitate the membrane fibers, further loosening any remaining cake. Filtrate is not made during this scouring. The air scour can be performed on a less frequent basis depending on how severe the turbidity of the water is.

Using Chemicals to Clean a System
Although backwashing and air scouring cleans the membranes effectively, there comes a point when it will take a chemical cleaning to restore the membranes to their normal filtration capabilities. Here, a closed loop is formed and cleaning chemicals are circulated through the system. The filtrate is dumped to drain and the reject is recirculated back into the cleaning tank.

The cleaning is stopped, the unit is restored to normal operating mode, and all filtrate is dumped to drain for a set amount of time. Normal operation can then be resumed and the new TMP should read near the level of a new membrane. When backwashing, air scouring and chemical cleaning will no longer reduce the TMP, the membrane is considered to be fouled and must be replaced.

Cleaning Frequency
There are several factors that affect the cleaning frequency for a membrane-based system. The main ones are operational recovery and the filtrate flux rate. These system factors are optimized to produce the maximum amount of filtrate with the smallest possible cleaning frequency per the end user's needs.

As a rule of thumb, the higher the system recovery and flux rate, the shorter the productive run time will be. Subsequent cleaning frequency will also increase. By increasing the reject rate, you can allow more of the concentrated, rejected material to be removed via the higher flow rate.

In doing so, it will take a longer time to grow a large film of reject material on the membrane surface thus improving the membrane's productive life between cleanings. Operational recovery is the ratio of filtrate made to the feed flow rate expressed as a percentage. Therefore, if the recovery is raised, permeate output increases accordingly, as does the flux rate.

Ultrafiltration

Ultrafiltration employs the use of a porous fiber that filters out most unwanted constituents in feed water. These membranes have pore sizes in the range of 0.01 to 0.1 microns. There are several types of ultrafiltration membranes such as hollow fiber membranes and spiral wound membranes.

As an example, a spiral-wound membrane consists of flat sheets wrapped in a spiral configuration similar to a reverse osmosis membrane. The pores in a hollow fiber membrane or spiral wound membrane should be consistently on the order of 0.02 to 0.04 µm in size.

The Purpose of Ultrafiltration
Ultrafiltration provides the end user with the ability to consistently and efficiently remove suspended solids, bacteria, yeast, many viruses, and harmful biological contaminants such as Giardia Lamblia and Cryptosporidium from feed water. Typical fiber material is dependant on the manufacturer and application, but can be commonly found in PVDF (Polyvinylidenefluoride), Polyacrylonitrile or Polyethylene. Material choice can be dictated by the Molecular Weight Cutoff of the membrane material. A membrane containing a smaller MWCO provides better overall filtration.

Ultrafiltration Applications
There are a multitude of applications for ultrafiltration ranging from pretreatment for the offshore industry to the pharmaceutical industry. This filtration method is commonly used at municipal drinking and wastewater treatment plants as both a pretreatment and polishing mechanism.

A Cost Effective Solution
Ultrafiltration can be very cost effective in comparison to multi-media and cartridge filtration systems due to having the ability to regularly clean the membrane and continue service for much longer periods of time. Filter cartridges typically must be replaced quite often depending on the level of suspended solids and do not provide the level of filtration equal to ultrafiltration. This lack of filtration can lead to more frequent downstream equipment maintenance due to faster foulant build-up.

A Closer Look at a Ultrafiltration System
A typical ultrafiltration system consists of a skid frame containing racks that can hold several membranes with valves and instruments to help monitor system properties such as pressure, flow, and backwash frequency. Typical feed pressures for ultrafiltration systems are from 30 to 50 psi. Filtration can occur in one of two ways with a hollow fiber membrane: outside to in, or inside to out. Ultrafiltration systems are usually operated in a cross flow mode so a small amount of concentrated dirty water is continually sent to waste.

The total amount of filtrate (filtered water) that the membrane makes each day per square foot of membrane surface area is know as flux. Flux is measured in gallons of filtrate per square foot of membrane surface per day. Membrane manufacturers have a ceiling value for the acceptable flux range of any certain element.

Flushing and Backwashing
While a ultrafiltration system is in operation, it is often flushed and backwashed to remove deposits from the fiber surfaces. However, the system will eventually need to be cleaned to caked solids that flushing and backwashing can no longer remove. This returns the system to its most effective level of performance.

The main parameter used to show the effectivity and operational cleanliness of a system is transmembrane pressure, or TMP.When this pressure rises to 30 psi or higher, the suspended solids and other impurities in the water have "caked" on the membrane surface. The loss in pressure as the water moves across the membrane surface exemplifies the level of this caked material. The pores in the membrane wall are effectively clogged and filtrate flow is drastically reduced when the TMP has risen to the upper end of the allowable range.

At this point the unit can be backwashed with permeate for a specified amount of time and at a particular flow rate. This basically works in reverse of the normal flow path and forces filtrate at a higher flow rate back through the pores, dislodging the cake on the membrane surface. The resulting freed particulate is sent to drain.

To further aid in cleaning the membrane surface, a pressurized air scour can also be utilized to help dislodge additional caked-on material. Low-pressure air is injected into the feed flow at the normal flow rate. This air helps to agitate the membrane fibers, further loosening any remaining cake. Filtrate is not made during this scouring. The air scour can be performed on a less frequent basis depending on how severe the turbidity of the water is.

Using Chemicals to Clean a System
Although backwashing and air scouring cleans the membranes effectively, there comes a point when it will take a chemical cleaning to restore the membranes to their normal filtration capabilities. Here, a closed loop is formed and cleaning chemicals are circulated through the system. The filtrate is dumped to drain and the reject is recirculated back into the cleaning tank.

The cleaning is stopped, the unit is put back into normal operating mode, and all filtrate is dumped to drain for a set amount of time. Normal operation can then be resumed and the new TMP should read near the level of a new membrane. When backwashing, air scouring and chemical cleaning will no longer reduce the TMP, the membrane is considered to be fouled and must be replaced.

Cleaning Frequency
There are several factors that affect the cleaning frequency for a membrane-based system. The main ones are operational recovery and the filtrate flux rate. These system factors are optimized to produce the maximum amount of filtrate with the smallest possible cleaning frequency per the end user's needs.

As a rule of thumb, the higher the system recovery and flux rate, the shorter the productive run time will be. Subsequent cleaning frequency will also increase. By increasing the reject rate, you can allow more of the concentrated, rejected material to be removed via the higher flow rate.

In doing so, it will take a longer time to grow a large film of reject material on the membrane surface, thus improving the membrane's productive life between cleanings. Operational recovery is the ratio of filtrate made to the feed flow rate expressed as a percentage. Therefore, if the recovery is raised, permeate output increases accordingly, as does the flux rate.

The LWP utilizes the Ultrafiltration (UF) membranes for primary pre-filtration and Reverse Osmosis process to produce potable water from virtually any raw water source. The LWP is comprised of five modules, one Basic Issue Item (BII) box, one Components of End Item (COEI) box, two collapsible fabric water tanks, and associated equipment.

Water is processed according to the following schematic shown below:

LWP Process Flow

The raw water strainer is anchored in location by tying a sand bag provided in the BII box to it. The float has 410 micron screen which provides the first stage of filtration in the process. This part is stored inside COEI box when not in use. Two sections of 1-1/2 inch diameter, 25 ft. long hoses are used to pipe the water from the source to the raw water pump.

The Raw Water Pump is used to draw the water from the source into the settling tank. This pump is stored inside the Pump module when not in use and has a 1-1/2 inch stainless steel camlocks as an intake fitting. All service pumps are interchangeable. For example, in case of raw water pump failure, the distribution pump, or any of the other service pumps, can be used to replace it simply by switching the intake fittings.

The 1000-gallon collapsible fabric tank receives the raw water from the water source. The water is then drawn from just below the surface inside the settling tank through a 200-micron floating strainer. In case of chemical pump failures, the 1000-gallon tanks can serve as reservoirs for batch treating the water with chemicals.

The floating strainer is placed inside the settling tank and connected to the settling tank outlet spool piece to draw the water from near the surface. The water is strained through a 200-micron strainer before entering the UF module.

A Booster pump is used to draw water from the settling tank and into the UF module. The primary function of the UF module is to pre-filter the water before the RO membranes. It is accomplished by means of three 35-mil UF cartridges that can filter suspended particles, bacteria and microorganism. They are capable of producing filtrate water with less than (0.1) NTU. The UF membranes offer the advantage of prolonged RO membrane life due to micron size removal regardless of the feed water conditions and elimination of disposable filters. The filtrate is then stored in the filtrate tank.

A 40-gallon capacity filtrate tank is attached to the UF module. The purpose of this filtrate tank is to provide filtrate for backwash and fast flush while allowing continued operation of the high-pressure pump and thus potable water production. The backwash pump is used to draw water from the filtrate tank for backwashing and fast flushing operations.

The High-pressure pump is driven by a diesel engine and is used to pressurize the filtrate water up to 1200 psi for the RO membranes. The pump draws the water from the filtrate tank on the UF module and feeds the RO module by means of a braided stainless steel hose. The Reverse Osmosis module consists of seven RO membranes in series. The water is fed from the high-pressure pump and this high-pressure forces the water through the RO membranes. Approximately 30 % of the filtrate is recovered as permeate and passed on to the chemical module. The rest of the concentrate or brine is discharged as reject. The permeate from the RO module is passed through the chemical module where it is metered in the totalizer and receives the chlorine injection for residual disinfection.

The product tank has a capacity of 1000-gallon and is used to stored product water before distribution. The distribution pump is used to supply product water at a rate of 10-gpm through a nozzle. The nozzle is to be kept off the ground by using the Service pump module frame.

Q: How does MECO's LWP treat all sources including seawater, brackish water and NBC contaminated water?

A: Most conventional military water treatments only treat one type of water, i.e. freshwater with minor contaminants. The key to the MECO's LWP is membrane-based filtration, which filters out all dissolved ionic material (i.e. seawater) and particulate matter (i.e. baterica, e coli, virsuses). Automated processes and controls eliminate the use of chemicals for operation.

Q: Is filtration necessary in the feed to a RO unit?

A: Yes, small particulate matter will embed itself into the first element of the RO array. This will reduce the life of this element, as well as increase the pressure drop through the RO unit.

Q: Is there any benefit to using Membrane Filtration instead of the standard multi-media filtration?

A: The Membrane Filter removes suspended solids down to .01 micron, as well as other contaminants such as bacteria and some viruses. Multi-media filters (MMF) / cartridge filters will only remove suspended solids to approximately 1-5 micron. When feeding an RO unit, the MF system will significantly reduce the bio-fouling, as well as reduce the SDI to below 1.

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.

» Launch MASTERsupport™ Online

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