In a move to strengthen its position in water treatment, chemical giant BASF recently announced that it will acquire German water filtration membrane developer inge watertechnologies (inge).

Inge makes ultrafiltration systems used to treat drinking water, wastewater, and seawater and specializes in filtration modules and rack designs for water treatment plants.

Inge owns a couple of international patent applications relating to its water treatment technologies, as well as at least one U.S. application and one European application. 

The international applications are WO/2010/121628, entitled “Backflushing filtration module and filtration system for cleaning fluids contaminated by particles” and WO/2009/003887, entitled “Filtration system comprising a plurality of filtration modules connected in parallel.”  Inge’s European application is EP2158958, entitled “Device and method for backwashing filter membrane modules.”

U.S. Patent Application Publication No. 2010/0051544 (’544 Application) is directed to an apparatus and method for backwashing filter membrane modules. 

Module rows (1a-1d) consist of four individual membrane modules, and each individual module includes a bundle of individual filtration modules.  The rows (1a-1d) together form a module rack.

Supply/drain lines (7a, 7b) carry raw water, which is supplied to each filter membrane module (2) through supply/drain ports (3a, 3b).  After filtration, the filtrate is drained via drain ports (4), flows through control valves (11a-11c) to filtrate collection line (5), and exits the module rack at central filtrate valve (6).

In backwashing mode, control valve (11b) of module row (1a) is closed on the supply side while the associated control valve (11a) on the drain side is open.  The supply side control valves in supply/drain line (7b) remain open. 

Thus, in the backwashing mode the filtrate produced by module rows (1b-1d) is pressed backwards through first module row (1a) to clean the filter membrane modules in that row.  The polluted backwashing water leaves through drain port (10) of the module rack via the other supply/drain line (7a). 

Each of the remaining module rows (1b-1d) is subsequently backwashed in succession in the same manner.

According to the ’544 application, this approach reduces the risk of contamination due to water stagnating in a backwash reservoir. 

Also, because some module rows continue to produce the filtrate that is used for backwashing while one of the rows is being backwashed, the invention eliminates the need for a backwashing pump:

The advantage of the approach according to the present invention lies in particular in that a backwashing reservoir with the associated backwashing pump can be dispensed with. This is because, during the backwashing mode, with the exception of the module row to be backwashed, the remaining module rows are operated in the filtration mode, so that they produce filtrate which is directly used for backwashing the module row switched in the backwashing mode.

According to the inge press release (inge_release), the acquisition is expected to close in Q3 2011.

Energy Recovery Inc. (ERI), a company based in San Leandro, California, has developed technology that reduces the amount of energy required for desalination. 

The technology does not directly relate to filtering water, but instead harnesses the pressure in the wastewater stream of reverse osmosis systems and transfers that pressure to the incoming feed stream to reduce the energy required to run the desal process.

According to ERI’s web site, the technology in its PX device (pictured above) has led to seven U.S. patents and international patents. 

Tim Dyer, the company’s CTO, commented on ERI’s IP.  ”We innovate and create intellectual property along the way to address existing and emerging industrial energy recovery needs.  Our strategy drives our IP, and our IP drives our strategy.”

U.S. Patent No. 7,201,557 (’557 Patent) relates to some of ERI’s fundamental innovations.  Entitled “Rotary pressure exchanger,” the ’557 Patent is directed to a pressure exchange apparatus for transferring the pressure of a high pressure fluid stream to a lower pressure fluid stream.

The rotary pressure exchanger (11) has a housing (13) containing a rotor (15) with a plurality of channels (16).  A low pressure seawater feed stream from a reverse osmosis system is pumped through a straight inlet conduit (39) and fills an inlet passageway (41).

At the same time, high pressure brine from the reverse osmosis system is pumped through an elbow conduit (51), fills a plenum chamber (53) and enters axial channels (16), causing the rotor (15) to spin.

As the rotor (15) spins, there is periodic alignment of each channel (16) with the opening to a discharge seawater passageway (65) in an upper end cover (19).  According to the ’557 Patent, whenever this alignment occurs the seawater in the channels is instantly pressurized.

Thus, the pressurized seawater is caused to flow out of the channels, fill an upper plenum chamber (45) and exit through an elbow discharge conduit (43).

Similarly, when a rotor channel (16) is aligned with the opening to the seawater inlet passageway (63) and the opening to the brine discharge passageway in the lower end cover (21), the seawater forces the low pressure brine out of the pressure exchanger (11) through the straight discharge conduit (49). 

ERI’s pressure exchanger has the advantage of simplicity, with the rotor being the only moving part.  The rotor and associated components seal the high pressure portion of the reverse osmosis process by keeping high and low pressure separate without the need for pistons.

According to ERI’s web site, the PX device makes desalination more economical and less energy intensive by reducing the amount of energy required by up to 60%.