Membrane Wastewater Treatment: A Reliable And Cost-Effective Solution In Brazil

For more than twenty years, Efluentes Industria è Comercio de Equipamentos Ltda. located in the city of São Paulo in São Paulo, Brazil, has been a leader in designing and engineering wastewater treatment facilities. Founded in 1980 by João Roberto Nunes Sr., this family-run business has now installed more than 500 wastewater treatment plants in Brazil and is quickly expanding its presence throughout South America with additional facilities in Uruguay and Chile.

Although Efluentes is an expert in using biological and chemical processes to treat industrial wastewater, sanitary wastewater and combined effluent, it has recently turned to membrane technology as a cost effective and environmentally friendly alternative.

Reducing Costs and Environmental Impact

In 1972, eight years before Nunes Sr. started Efluentes, he installed a chemical-based system to treat oily wastewater at MWM, now MWM International, a leading diesel engine manufacturer located in São Paulo, Brazil. The system first treated the wastewater through acidulation, then coagulants were added, and the soluble oils were separated by flocculation.

Although the system was efficient, it had several drawbacks. Four people were required to operate the system 24 hours a day, 6 days per week, making it a costly, labor intensive process. It also generated a large volume of sludge, which was expensive to dispose of, and did not conform with the company's evolving environmental policy. The high operational costs and need for a more environmentally sound system led MWM to seek an alternative treatment method that could meet both of those requirements and sustain a continuous high volume of wastewater treatment.

Ultrafiltration Tubular Membranes

In the late 1990's, Efluentes performed a pilot test at MWM using an ultrafiltration (UF) system with FEG™ tubular membranes from Koch Membrane Systems, Inc. (KMS) of Wilmington, Mass., U.S.A. Two weeks was all that it took to convince MWM that the membrane system could cost effectively treat the wastewater with contaminant removal efficiency of more than 99 percent, while also adhering to MWM's environmental policy.

The new system was better for the environment because it did not generate sludge and no chemicals were needed to separate the soluble oils. Since the system was automated, operational costs were significantly lowered and labor expenses were reduced. While the old chemical-based system required four people to operate it, the new system only needed one. Cleaning frequency was also significantly reduced from a daily cleaning to one every four days taking no more than two hours.

Eliminating the sludge generation also eliminated the high cost of its disposal. The membrane system produced a small volume of concentrated waste that remained inside the UF process tank. After two weeks of continuous operation the process tank was drained, and the reject was sent to a waste disposal company.

MWM installed 96 FEG membranes from KMS, and shortly thereafter experienced a 70 percent reduction in operational costs. The company was particularly happy with these results, since previous estimates had suggested that the installation of a UF system for an oily wastewater application would result in cost savings of no more than 50 percent.

For more than 6 years, the membrane system has been successfully treating oily wastewater using the original FEG membranes. The most rugged and versatile of all configurations available from any membrane manufacturer, the FEG tubular membranes typically last up to 10 years.

The FEG membranes have been in use worldwide for more than 30 years, removing oily wastes and metals from wastewater streams in a variety of industries. They also successfully and repeatedly process wastewater with high suspended solids and can be used to concentrate product to relatively high end-point concentration levels without significant flux loss or plugging.

Because of their ability to accommodate mechanical cleaning with spongeballs and their chemical resistance properties, the FEG tubular membranes are the preferred membrane configuration in tough waste treatment situations. The unique spongeballs also enhance chemical cleaning by reducing CIP time and the amount of cleaning chemicals needed.

Hollow Fiber and Spiral Membranes Recycle Biologically Treated Effluent

MWM was so pleased with the performance of the UF system and FEG membranes that it installed a second system that also employs membranes from KMS. The additional system serves as a complementary solution to MWM's activated sludge system and recycles biologically treated effluent for reuse within the plant. The goal is to recycle 50 percent of the total wastewater that leaves the facility.

MWM's technical team, in cooperation with Efluentes and KMS, conducted a cost analysis to find out how much the new system would save them. The customer's inlet municipal water costs are $13.5 per 1,000 U.S. gallons. With the recycling system, 50% less municipal water will be used. Since daily consumption has dropped to only 27,000 gallons, the savings amounts to $10,935 per month, providing a return on investment that will enable the customer to repay the total cost of the new UF system and membranes in less than 3 years.

To help meet MWM's goal, Efluentes installed a UF system with six, 8-inch TARGA® hollow fiber cartridges and eight, 8-inch TFC®-XR RO spiral membranes, both of which were designed and manufactured by KMS. The new system enabled MWM to recycle 4 m3/h (17.6 gpm) of RO permeate for reuse in cooling towers, engine washers, and other applications.

The TARGA UF cartridges were selected because they are designed to remove particulates, colloids and larger molecular weight components, and are particularly effective as pretreatment for spiral RO membranes.

"The RO elements produced by KMS had an excellent report of success in several types of applications, and it did not make sense to use another membrane manufacturer," said João Roberto Nunes Jr., owner and engineer at Efluentes.

Spiral membranes provide a cost effective solution for applications with low suspended solids concentrations and minimal available space. The TFC-XR spiral membranes are designed specifically to recover pure water from brackish water or waste streams with high salinity. They are also extremely robust in that they can withstand pressures in excess of 1,000 psi.

Reliable and Cost-Effective Performance

Since MWM installed the two membrane systems, it has experienced significant decreases in operational costs while simultaneously complying with the company's environmental policy. This success story is just one of many resulting from the partnership between Efluentes and KMS.

Today, Efluentes uses a variety of membranes from KMS to treat various types of wastewater including wastewater with high concentrations of oil and heavy metals. Other applications include polishing sanitary wastewater and alkaline cleaner recovery. Because of the good experiences Efluentes has had with KMS and its membranes, Nunes is trying to persuade more customers to use membranes instead of chemical-based processes.

"I can say that in membrane technology, my partner is always Koch Membrane Systems, and each project is completed by two hands: Efluentes and KMS together," said Nunes. "I can also say that for the systems in Brazil where we have installed KMS membranes, the customers are very happy in terms of membrane life, permeate quality, replacement policy, etc."

SOURCE: Koch Membrane Systems, Inc.