Use of a pretreatment absorbent cartridge in an ethylene glycol recovery operation has cut nanomembrane replacement costs by more than 50% at one company. In addition, downtime for membrane cleaning has been cut by about one-third, and batch process time has been reduced by approximately 15%, according to the company's president. When labor and energy savings are considered, he judges the consequent in-crease in annual throughput to be at least 25%.
The Fulflo TruBind pretreatment absorbent cartridge, manufactured by Parker Hannifin Corp.'s Process Filtration Div. in Lebanon, Ind., incorporates a proprietary modified polymer that absorbs and chemically binds contaminant hydrocarbons inside the unit's interior matrices.
"When those petroleum and emulsified oils hit the nanofilters, it'll take them out in a heartbeat," said Robert J. Kolhoff, president of Anti-freeze Recycling Inc. "When we replaced a nano set in March 2000 with the new pretreatment in place, we didn't have to replace the nano set again until October." Kolhoff added that when the operation ran without the cartridge for a couple of weeks, the set had to be replaced within three months.
"Overall, we figure we're getting 25% more throughput annually while keeping membrane cost at 0.3% of production cost vs. 1% or more for other filters." Kolhoff added there has been no adverse effect on his efforts to comply with GM 1825M specification for process line output re phosphate- or borate-based corrosion/scaling inhibitor content. The spec is checked quarterly or when any change in the process or its equipment occurs.
At Antifreeze Recycling, each pretreatment cartridge processes 500 to 1,000 gal of waste antifreeze, collected from automotive repair shops and over-the-road truck repair and maintenance facilities. The absorbent cartridge serves as the final step in a pretreatment process that begins with three-phase polypropylene filtration that steps down from 20 to 5 to 1 Km pore size to meet the initial contact with traces of contaminants such as motor lube oil, transmission fluid, emulsified oils, diesel fuel, organic foulants, metallics and minerals.
In the subsequent treatment phase, Kolhoff explained that fouling of the four-stage, thin-film membrane (TFM) nanofilters is monitored by measuring flow rates and pressure drops through them.
"We should get a 5 psi drop per membrane," he said. "At 15, we've got big problems. We like to run a flow of 7 to 10 gal/min, and that could easily drop by 25% if there's enough membrane contamination. If things are going well, we can process 500 gal of feedstock between cleaning outages."
Kolhoff added that the addition of the new pretreatment cartridge has helped considerably in his efforts to realize the benefits from the nano-phase installation.
The 4.5" dia., 20" long absorbent cartridge, contained in a clear plastic vessel with side-seal dead-stop screw top, serves as the final step in the process line's pretreatment process. Feed-stock off-loaded into a first batch tank is air-diaphragm pumped through the pretreatment array at about 3 to 4 gal/min and deposited in a second batch tank for high-pressure pumping to the nanomembranes.
"It's essentially a reverse osmosis (RO) operation but not as tight," Kolhoff noted. "It reduces molecular weight to 200 on the Saccharide Scale vs. 1 for RO."
According to Parker Hannifin, its absorbent cartridge also has worked well in reverse osmosis applications, where membrane filtration is down to 0.0001 Km.
In addition to removing hydrocarbons from coolants like ethylene glycol, it has effectively reduced oil, lubricant, grease and solvent contamination needed for quality control and discharge compliance for a industrial water processing, washing, runoff and disposal operations.