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Carribean Boxplant Goes to
Zero Discharge

Cassie Rothstrom and John Kohl


In January of this year, Walla Walla Environmental and Harper/Love Adhesives sent in a Zero Discharge Team consisting of Jorge Romero and Marcello Marino from Harper/Love Adhesives, and Roger Corn from Walla Walla Environmental, to a locally based Caribbean boxplant. The plan was to reformulate this boxplants’ current starch adhesive formula to include the use of untreated flexo wash-up and corrugator run-off process waters in the secondary portion of the starch adhesive batch.

By following a proven procedure developed by this Zero Discharge Team, the addition of this process water was done so with success. This protocol included evaluating the water to be used for known constituents that would cause drastic viscosity and gel swings and impede the bonding process; making the necessary starch adhesive formulation changes; auditing and making recommendations to the facility for specific engineering changes; implementing a water reduction program; and conducting a start up with the process water to assure stable viscosity, gels and bonding at the corrugator were obtained.

Background

The driving force for this facility to go to Zero Discharge was not due to any heavy surcharges, or the need to be environmentally compliant. Very simply, they wanted to do something good for the environment, the city they are located in, and to protect future generations. This, in and of it self, is rare. Usually, a boxplant will decide that it wants to go to Zero Discharge because they can no longer meet the environmental compliance issues involving the discharge of this process water to their local municipality and/or the surcharges associated with discharging this process water to the municipality are becoming quite cost prohibitive.

This boxplant’s average basis weight is 150 lbs., with 85% of this being 175 lbs. The following are the average quality measurements for this boxplant over the past two months: Pin Adhesion is 99.88 psi, Caliper is 165.2 mil per inch, and the average production threw put on the finishing side was 2.8 MMSQM. This facility runs a single viscosity starch adhesive formula. Their machine limitations include an older C flute single face and glue machine with older glue rolls. The starch mixing equipment is a vintage single tank mixer that needed improved agitation.

Possible Challenges

The Zero Discharge Team had some concerns in starting up this facility on the process water. They included viscosity variations from suspended solids in the process water to be used; viscosity drops from high concentrations of bacteria in the process water; gel point and viscosity swings from the variability in process water pH being introduced into the adhesive.

The other concern was the facilities’ need to reduce the amount of process water that it currently produced by 2000 gallons per day. Successfully using the process water in the secondary portion of the starch adhesive batch was only part of the puzzle to get this facility to Zero Discharge. If they produced more water than they could consume, Zero Discharge would never be achieved.

Implementation

Prior to starting up this facility on the process water, some changes had to be made at the plant. Walla Walla Environmental provided the facility with engineering schematics that included plumbing and sizing of pumps, lines, tanks, and electrical. This included retrofitting the starch kitchen and developing a system by way of plumbing from the underground clarifyers to the 4000 gallon holding tank with internal jet agitation, and installing a pump to move the stored water directly to the secondary portion of the mix tank.

Once these mechanical and electrical changes were made, the chemistry portion commenced. The Zero Discharge Team had conducted a raw water analysis prior to their arrival and found several constituents in this process water that needed to be addressed. These included pH, tri-sodium phosphate (TSP), B.O.D.’s, C.O.D.’s, Calcium, and water hardness.

The process water was used as the secondary or cooling water in the adhesive formulation. This represented 50% of the total water in the batch. Since the process water was untreated the pH was consistently elevated (in the 10 pH range) causing premature raw starch swelling and viscosity increases. The caustic soda amount used in the formula needed to be reduced to offset this higher pH. When reducing the caustic levels the penetration into the substrates was reduced since the caustic acted as a wetting agent. We introduced Harper/Love’s HL-7 product to the formula that reduced the batch pH and allowed the normal amount of caustic to be used.

The use of trisodium phosphate (TSP) needed to be eliminated, as it is a food source for bacteria. The high levels of B.O.D.’s and C.O.D.’s, which indicate a lot of bacteria, did not concern the team because they intended to make formulation adjustments that included the addition of a quick kill biocide. The plant set up an automated system that adds 19 ounces of Aquacide quick kill biocide from Walla Walla Environmental to each batch of adhesive. This product is key to successfully using this process water to make starch adhesive. Bacteria, if not aggressively controlled by a quick kill biocide like Aquacide, will begin eating the starch solids and can cause rapid viscosity loss, increased gels, and poor bonding on the corrugator.

And finally, this water also contained higher than normal concentrations of calcium carbonate from the flexo ink fillers. This higher calcium carbonate will plate out on the glue rolls and fill the adhesive carrying cells, reducing application of starch on the flute tips. By adding 4 ounces of Calciban to each batch of starch adhesive, the issue of calcium scale plating out on the glue rolls was not an issue. This calcium scale inhibitor prevents the calcium from crystallizing and adhering to the glue rolls.

While at the facility, it was visually noticed by the Zero Discharge Team that there were two oil leaks on the single facer. This problem was dealt with and eliminated prior to the start up on the process water.

During this entire process, the crew in this plant was very positive and enthusiastic about going to Zero Discharge. This is a credit to management. They conducted several crew-training meetings on this process and encouraged open communication by the crew on their questions and concerns. This type of crew training is perhaps one of the most important parts of the successful implementation of Zero Discharge. Without support for this project from the senior management clear down to the part time employee, Zero Discharge is tough to maintain with much success.

Corrugator Performance

The corrugator run speeds were not reduced with the process water introduction, but instead were actually increased by 20 meters per minute with the addition of the HL-7! The facility continued to run the process water for a period of two weeks, and then discontinued its use until the week of April 16th, so that some additional mechanical, electrical, and maintenance issues could be resolved. They are now running process water in every batch of starch adhesive and intend to be at Zero discharge by July of this year.

Water Conservation Program

Once it was established that the process water could be used with success, then the process of putting the facility on a “water diet” began. The goal was to reduce the total amount of water produced by this facility by approximately 2000 gallons per day. The installation of water saver nozzles on each water hose in the plant, and the installations of water meters on the lines to the flexos were installed and the water diet has begun. The facility continues with its crew training on water conservation.

The process of water reduction in order to achieve Zero Discharge will take this facility some time. But once the water production levels don’t exceed the amount of water the boxplant can consume, Zero Discharge will be achieved.

Final Result

At the end of the second day in the plant, all retrofitting was complete, all chemical changes had been made, and the new adhesive formula was established. On the third day, the formula was put through a rigor of tests and, as expected, was shown not to impede the bonding process, but instead to produce a good bond. Corrugator speeds were up by 20 meters per minute, board quality was not compromised, and the facility had accomplished what it intended to do … become an environmentally aware company for the community that they are located in.


This article was written by Cassie J. Rothstrom, Chief Operating Officer of Walla Walla Environmental, Inc., and John Kohl, for Harper/Love Adhesives Corporation.