UF/RO Aids Pharmaceutical Plant’s Drive To Zero Liquid Discharge

June 1, 2007
To enhance water and waste minimization, Pfizer turns to ITT Corp.’s Aquious business to revamp an old RO membrane system at one of its five Puerto Rico plants with a UF/RO system to save on water and energy due to less pressure required of pumps.

To enhance water and waste minimization, Pfizer turns to ITT Corp.’s Aquious business to revamp an old RO membrane system at one of its five Puerto Rico plants with a UF/RO system to save on water and energy due to less pressure required of pumps.

Puerto Rico supports a large pharmaceutical manufacturing infrastructure. With favorable tax incentives and sophisticated communications and transportation system, Puerto Rico manufactures many of the most prescribed medicines in the United States. Like most islands with modern infrastructure and manufacturing, though, it faces a finite supply of resources - especially water.

Pharmaceutical giant Pfizer has a leading manufacturing presence in the Caribbean island, with five plants employing more than 5,500 people that produce some of the company’s top selling medications - including Celebrex, Lipitor, Neurontin, Norvasc, Zoloft and Zithromax. At its facility in Fajardo, Puerto Rico, Pfizer initiated a water conservation and waste minimization program with a goal of reusing 100% of its wastewater.

Efficient water reuse system needed

In its drive to make the plant a zero liquid discharge (ZLD) facility, Pfizer originally installed a reverse osmosis (RO) system to treat process water before returning it to non-potable water uses. The RO system was installed to reduce the volume of discharge water - 50,000 gallons per day (gpd) - previously loaded into tankers around the clock and trucked to a municipal waste treatment facility about two hours away. The water supply to the Fajardo plant comes from surface water originating from the nearby Yunque rainforest. Before entering the plant, the water undergoes conventional treatment from the municipality.

Ultrafiltration and reverse osmosis systems from ITT Aquious-Water Equipment Technologies are assisting industrial plants meet increasingly stringent requirements for zero wastewater discharge.
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In 2002, Pfizer contacted ITT Corp.’s Aquious division to discuss its wastewater treatment scheme. Pfizer was extremely displeased with operation of its existing RO system. Installed without a thorough engineering analysis, the RO system never operated correctly from the start. According to Mainor Vega, products manager for Latin America and the Caribbean with ITT Aquious’ Water Equipment Technologies (WET) unit, with headquarters in Boynton Beach, Florida, “When we visited the plant for the first time, they had a waste bin filled with old membranes. The customer was buying membranes on a monthly basis due to the inefficiency of the existing RO system, which resulted in astronomical operational costs.”

Two-stage system recommended

The customer was seeking to replace and improve its existing RO system. After analyzing the complete process, ITT’s engineers proposed an ultrafiltration (UF) system followed by a dual RO system. The UF system would provide a quality of feed water for the RO system that will allow for ease of operation and the best life cycle cost of the equipment.

At the Pfizer plant, the wastewater originates from the sanitary processes, the cafeteria and the cooling towers. There are many concerns when trying to recycle wastewater. For the RO system at this site, one of the biggest was the level of silica in the waste stream. This waste stream is first goes through a 13,000-gallon capacity clarification process. From there, the wastewater moves into a secondary effluent tank. In many facilities, this is where the waste treatment process would stop and discharge would take place into local waterways or be sent for further processing at a municipal wastewater treatment plant, depending on local regulations. From the secondary effluent tank, the wastewater is processed through a multilayer sand filtration system.

ITT’s engineers analyzed the sand filtration system to make sure the media loads inside the tank were correct and all valves for the automatic operation of the system were operating correctly. From the media filtration, the wastewater now enters the UF system. This pretreatment is important for the UF system to operate properly. The main purpose of having the UF system is for reduction of turbitity and SDI. The RO membranes wouldn’t operate for long without this layer of protection.

Hollow fiber membranes

The new system installed at the plant includes a 50,000-gpd UF system and a 30,000-gpd RO system. The UF system takes care of suspended and colloidal matter and acts as a barrier to provide a quality of water to where the RO membrane system can operate properly. The UF system contains hollow fiber style membranes that go through a series of flush cycles during the day (up to 200 cycles per day) to keep the dirty water from sticking to the UF membranes. The result of the UF treatment is to lower the SDI and provide good quality water to the RO membranes.

From the UF system, treated water goes to a 1,000-gallon filtration tank where a set of re-pressure pumps feed it to the RO system with the addition of pretreatment chemicals. ITT designed and installed two 30,000 gallon per day RO systems on a single chassis to provide the customer with redundancy. In this lead-lag approach, the RO system receives a signal from the permeate tank and a computer would direct one or the other RO system to turn on so that there’s an even wear across the system. In addition, the RO system was designed with low fouling membranes. This not only provides an additional level of security for the customer, but allows it to process water without use of the UF system in case of an emergency.

In an RO system, pressure is applied to push water molecules across a membrane to overcome the osmonic pressure. As the purified water ions flow across the membrane, any ions that have a high molecular weight (anything over 200 MWCO) are rejected. There are, however, some specific ions that will be rejected at a higher rate and some at a lower rate.

Efficiency lowers operating costs

Leaving the RO system is a quality of water pure enough to returns to the cooling tower. In the cooling tower, you normally have cycles of concentration. The amounts of cycles are dependent on the quality of the make-up and process stream. With the purified permeate water from the RO process blended with the normal cooling tower water supply, the customer was able to take the cycles of concentration up to new levels of efficiency.

From a previous total of 50,000 gpd of wastewater, the reject from the RO - now only 8,000 gpd - will go to a holding tank and, from there, into a tanker that takes it to a larger waste treatment facility. With a fraction of the wastewater now being disposed, the customer is realizing a tremendous reduction from the half a million dollars a year it was spending on tanker truck collection. As it continues to drive towards zero discharge, the customer is looking at new ways to reduce these 8,000 gpd of discharge by evaporation or heat to just a few pounds of solids.

Because the old RO system was operating so inefficiently, Pfizer had significant costs for membrane replacement. Chemical costs were also high because it was using anti-scalants at a high rate to keep membranes from fouling. The new UF/RO system has been operating since 2002 and the RO membranes haven’t been changed once. The addition of the UF system in front of the RO process also greatly reduces fouling tendencies.

Seen here is the skid-mounted RO unit that’s part of a UF/RO system installed at a Pfizer pharmaceutical plant in Puerto Rico
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And the facility is using much less power to run the system. Vega notes, “The old system was designed to operate at 400 to 500 psi. Our RO system is operating now at 105 to 107 psi.” That huge reduction in pressure provides the customer with significant energy savings. There are some additional pumps run with the UF system, but because it typically runs at about 15 psi, the additional energy costs are small.

Vega added, “With growing zero discharge regulations, we provide solutions for treating effluent that provides excellent water quality for non-potable water uses.”

In addition to providing systems for water reclaim, ITT Aquious has installed numerous microfiltration, UF, nanofiltration and RO system to purify water for use in the manufacture of pharmaceuticals, not just in Puerto Rico.

With over 35 years of experience in membrane filtration and over 500 installations in more than 30 countries, ITT Aquious is a complete global membrane treatment solution provider for desalination, surface water and industrial process solutions. Article supplied by Minett Media. Contact: www.aquious.com

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