Filtration System Brings Pharmaceutical Plant Closer to Zero Discharge

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Puerto Rico supports a large pharmaceutical manufacturing infrastructure. With favourable tax incentives and a sophisticated communications and transportation system, many of the most prescribed medicines in the U.S. are manufactured in Puerto Rico. Like most islands with modern infrastructure and manufacturing, Puerto Rico faces a finite supply of resources, especially water. Pfizer Inc. (New York, NY) has a leading manufacturing presence in Puerto Rico, with five plants employing more than 5,500 people. At its facility in Fajardo, Pfizer initiated a water-conservation and waste-minimization program with a goal of reusing 100% of its waste water.

New System Needed
In its drive toward making the plant a zero-discharge 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 — that previously had to be loaded up in tankers around the clock and trucked to a municipal waste treatment facility, which was approximately 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 by the municipality.
In 2002, Pfizer contacted ITT Industries’ (White Plains, NY) Aquious unit to discuss its waste-water treatment scheme. Pfizer was extremely displeased with the operation of its existing RO system. Installed without thorough engineering analysis, the RO system never operated correctly. According to Mainor Vega, products manager for Latin America and the Caribbean with ITT Aquious’ Water Equipment Technologies (Boynton Beach, FL) unit, “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
After analyzing the complete process, ITT engineers proposed an ultrafiltration (UF) system followed by a dual-reverse osmosis system. The ultrafiltration system would provide high-quality feed water for the RO system that will allow ease of operation and the best life-cycle cost of the equipment.
At the Pfizer plant, the waste water originates from the sanitation processes, the cafeteria and the cooling towers. There are many concerns when trying to recycle waste water. For the RO system at this site, one of the biggest concerns was the level of silica in the waste stream. The waste stream is first sent through a 13,000-gallon capacity clarification process. From that clarification process, the waste water moves into a secondary effluent tank. In many facilities, this is where the waste treatment process would stop and a discharge into local waterways would take place, or otherwise be sent for further processing at a municipal waste water treatment plant, depending on local regulations. From the secondary effluent tank, the waste water is processed through a multilayer sand-filtration system.
The sand-filtration system was analyzed to ensure the media loads inside the tank were correct and that all valves for the system’s automatic operation were functioning properly. From the media filtration, the waste water enters the UF system. This pretreatment is important to ensuring the UF system operates properly. The main purpose for having the UF system is to reduce turbidity and silt density index (SDI). The RO membranes would not operate for long without this layer of protection.
The system installed at the plant included a 50,000-gpd UF system and a 30,000-per-day RO system. The UF system takes care of suspended and colloidal matter and acts as a barrier to provide high-enough quality water to allow the RO membrane system to 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, the 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. Two 30,000-gallon-per-day RO systems were designed and installed on a single chassis to provide redundancy. In this lead-lag approach, the RO system receives a signal from the permeate tank and a computer directs one or the other RO system to turn on so that there is 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, but allows water to be processed without the 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 go across the membrane, any ions that have a high molecular weight (anything over 200 molecular weight) are rejected. There are, however, some specific ions that will be rejected at a higher rate and some at a lower rate.

Lowering Operating Costs
Leaving the RO system, the customer has high-quality water returning to the cooling tower, which features concentration cycles. The amount of cycles depends 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 improve the efficiency of concentration cycles.
The reject from the RO was reduced from 50,000 gallon of waste water per day to 8,000 gallons per day, which will go to a holding tank, and then a tanker that transports it to a larger waste-treatment facility. The reduction in disposed waste water translates into reduced spending on tanker truck collection. As it continues to drive towards zero discharge, the customer is looking at new ways to reduce the 8,000-gallons-per-day discharge to just a few pounds of solids through evaporation or heat.
Because the old RO system was operating so inefficiently, the customer had significant costs associated with membrane replacement. Chemical costs were also high because the customer was using a large number of anti-scalants to keep their membranes from fouling. The UF/RO system has been operating since 2002 and the RO membranes have not been changed once. The addition of the UF system in front of the RO process also greatly reduces the fouling tendencies.
The facility is also using much less power to run the system. Vega notes that, “The old system was designed to operate at 400 to 500 psi. Our RO system is operating at 105 to 107 psi.” That huge reduction in pressure provides the customer with significant energy savings. There are some additional pumps that are run with the UF system, but because the UF typically runs at about 15 psi, the additional energy costs are minimal.

ITT Industries’ Aquious unit is a complete global membrane treatment solution provider for desalination, surface water and industrial process solutions. Aquious has over 35 years of combined experience in membrane filtration with over 500 reference installations in more than 30 countries. ITT communications manager Bjorn von Euler can be reached at bvoneule@fluids.ittind.com