The LFNano™ can be used for a myriad of water treatment needs as it is extremely flexible relative to the source water quality.  This section briefly discusses a few of the more broad applications that will be greatly improved by the use of the system.

Wastewater – NF membranes have not been considered for wastewater treatment as their current embodiment requires significant pre-treatment that is expensive in wastewater.  NF membranes can reject organics to a very high degree, making them suitable for wstewater treatment without a biological digestion process.  Depending on the water source additional removal of nutrients might be required, but this is a simple additional process when the water is so clean.

Membranes can be used to treat about any water, but the cost effectiveness is often at issue.  NF membrane can be used on wastewater today but at tremendous expense. The LFNano™ simplifies membrane treatment making it competitive with many existing technologies.

Surface water – Surface water treatment can be improved greatly with an LFNano™ system as it removes far more contaminants than MF or UF systems and does so without any chemical addition to the feedwater as is common in other treatment systems today.  With no chemical addition, the system can be operated at low recovery rates leaving a chemical-free concentrate stream.  Also, at low recovery rates, even natural contaminants do not concentrate much. In such low recovery cases, the concentrate can be returned to the environment with no negative repercussions. Alternatively, a high recovery process is also possible without an increase in the osmotic pressure requirement as is common with RO membranes.

Pre-treatment – RO systems today require significant pre-treatment, generally with other membranes.  Traditional membrane pre-treatment uses low pressure membranes that do not remove much of the dissolved organics and scale forming ions.  It is these dissolved constituents that cause the fouling of the downstream RO or NF membranes.  By using the LFNano™ as pre-treatment, the feedwater to the RO stage will be void of the dissolved organics and most of the multi-valent ions that cause scaling.  The downstream membranes will then require little maintenance which will extend their useful life.

Emergency treatment – Many mobile treatment systems are constructed to provide clean water in emergency situations such as after a natural disaster or in military operations.  These mobile systems do not have the benefit of a thorough feed water analysis before they are needed so many contingencies must be accomodated.  This requires the transport of multiple treatment chemicals. The LFNano™ can handle a wide variety of feed waters with the same chemical-free process.  This makes it ideal for such contingency operations.

Chemicals are largely eliminated from the water treatment process with the LFNano™.  The production and use of chemicals is fraught with environmental impacts.  Further, the unintended consequences of byproducts created in our water by modern disinfection techniques will not be completely known for decades.  The LFNano™ system removes contaminants rather than chemically altering them or inactivating them (bacteria or viruses).

The LFNano™ membrane elements and vessels will occupy less space than a comparable MF or UF system. MF/UF backwash and cleaning systems require frequent backwash which requires a complex series of automated valves and controls.  The required chemical storage and injection equipment also occupies significant space.  When the LFNano™ is in pre-treatment mode ahead of an RO stage, the RO will be operated much more efficiently and not require maintenance shutdowns.  Therefore less RO capacity is required to maintain a consistent throughput.  The DXV LFNano™ system will have a more compact footprint in most all applications despite a lower packing density.

Man has been using water that has been purified the same way for millennia. As an example, the figure below shows how the Floridian Aquifer is replenished by the infiltration of surface water. This water is filtered by the soil as it percolates into the massive underground storage aquifers, naturally cleaning the water. In comparison, when we use a surface water source directly, it must be cleaned by other methods in order to ensure it is safe.                                                             

People have developed systems that mimic the way the Earth cleans water in aquifers by filtering the water through a bed of sand or other porous substrate. The current version of this method, Rapid Sand Filtration (RSF), is the way we treat most all surface water sources and even tertiary treated wastewater. This method of treatment is land and maintenance intensive as the media bed is frequently in need of backwashing. In addition, it does not provide a firm physical barrier and can be easily penetrated by contaminants if not operated properly.

In the 1980’s a few firms began to develop low pressure microfiltration (MF) and later ultrafiltration (UF) membrane systems that can treat water to a much higher quality than RSF. These systems were initially expensive and complex, but they provided a physical barrier to contaminants up to the 0.1 to 1 microns (millionths of a meter, 10^-6) range while sand filtration only effectively removed particles down to about 100 microns in size. These systems were adopted on a limited basis only as the incremental safety improvement they offered did not justify the significant complexity and expense.

Microfiltration and ultrafiltration membranes offered better removal of bacteria (MF) and even viruses (UF). When an outbreak of Cryptosporidium illness in Milwaukee in 1993 caused a reported 54 deaths, many started to look into more secure water treatment methods than traditional sand filtration. The concern caused by the Milwaukee outbreak created a demand for tighter filtration methods such as MF and UF membrane systems. As the cost of these systems came down, more applications became economical and membranes grew in usage. Currently MF and UF treatment are common in new installations, but still represent a small fraction of the installed treatment capacity in the United States.

This trend was highlighted by a leading MF/UF membrane supplier in their 2005 annual report which showed the pickup in the demand for their membrane systems as the cost of treatment came down over time. This leading low pressure membrane (MF/UF) supplier published the graph below in their 2005 annual report.

 

It is clear that the reduction in the cost of membrane treatment stimulated significant demand as the cost dropped by 80% in the four years from 1995 to 1999. Today MF and UF systems are used to treat drinking water, pre-treat RO feedwater, and treat wastewater in membrane bio-reactor (MBR) systems. However, their frequent fouling and high maintenance cost still limit their adoption. In addition, for pre-treatment applications ahead of high pressure membranes, they do not remove many of the organic and scale producing foulants resulting in frequent cleaning of the RO membranes.