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Aquious Filtration System Assists Drive Toward Zero Discharge
For many people, the image of Puerto Rico brings to mind sunny beaches, glamorous hotels and wet, mountainous rain forests. Lesser known is that the island also sports a large pharmaceutical manufacturing infrastructure. With favorable 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. The pharmaceutical giant, Pfizer, has a leading manufacturing presence in Puerto Rico, 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 Reuse 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 gpd—that previously had to be loaded into tankers 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 El Yunque Rain Forest. Before entering the plant, the water undergoes some conventional treatment from the municipality.
In 2002, Pfizer contacted ITT Industries’ Aquious unit to discuss their wastewater treatment scheme. Pfizer was extremely displeased with the operation of their existing RO system. Installed without a thorough engineering analysis, the RO system never operated efficiently from the start. According to Mainor Vega, products manager for Latin America and the Caribbean with ITT Aquious’ Water Equipment Technologies unit, headquartered in Boynton Beach, Fla., “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.”
The customer was seeking to replace and improve their 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 allowed 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 concerns was the level of silica in the waste stream. The waste stream is first sent through a 13,000-gal capacity clarification process. From that clarification process, 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 that the media loads inside the tank were correct and that all valves for the automatic operation of the system were operating correctly. From the media filtration, the wastewater 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 turbidity and SDI. The RO membranes would not operate for long without this layer of protection.
The system ITT installed at the plant included 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, the treated water goes into a 1,000-gal 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 gpd 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 directs one or the other RO systems to turn on so there is an even wear across the system. In addition, ITT also designed the RO system with low fouling membranes. This not only provides an additional level of security for the customer, but allows the customer to process water 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.
System Lowers Operating Costs
After leaving the RO system, the customer has quality water that returns to the cooling tower. A cooling tower normally has cycles of concentration, due to silica or other SDIs that makes the system less efficient. The number of cycles is dependent on the quality of the make-up and process stream. With the purified permiate 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 gal of wastewater per day, 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 they were spending on tanker truck collection. As it continues to drive toward zero discharge, the customer is looking at new ways to reduce this 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, the customer had significant costs for membrane replacement. Chemical costs were also high because the customer was using anti-scalants at a high rate to keep the membranes from fouling. The UF/RO system installed by ITT 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 noted, “The old system was designed to operate at 400 to 500 psi. Our RO system is operating at 105 to 107 psi.” That 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 small.
“With growing zero discharge regulations, we provide solutions for treating effluent that provide excellent water quality for non-potable water uses,” Vega said. In addition to providing systems for water reclaim, ITT’s Aquious unit has installed numerous microfiltration, ultrafiltration, nanofiltration and RO systems to purify water for use in the manufacture of pharmaceuticals. wqp