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Takashi Otsuki, First Officer, Environmental Conservation Section, Environmental Conservation Department, Production Operations, Keihin Corporation

Takashi Otsuki, First Officer, Environmental Conservation Section, Environmental Conservation Department, Production Operations, Keihin Corporation

Disc dryer used to process release agent waste liquid at Miyagi Factory No. 1. Waste liquid sprayed onto the disc separates into steam and oily residue.

Disc dryer used to process release agent waste liquid at Miyagi Factory No. 1. Waste liquid sprayed onto the disc separates into steam and oily residue.

An unexpected solution to Keihin's growing waste issues

 Keihin came to Kakuda in 1969, when it built the Keihin Seiki Manufacturing Kakuda Plant (now Miyagi Factory No. 1, Kakuda Plant No. 1) to manufacture motorcycle and automobile carburetors. Production gradually expanded thereafter, and today the plant is a key facility for motorcycle, automobile, and power equipment products, primarily carburetors.
  One type of waste Keihin has reduced significantly at this plant is waste liquid containing spent mold release agent. The production process for carburetors includes a casting step in which hot liquid metal such as steel or aluminum is poured into a mold and then cooled, creating the shape of the desired part. Mold release agent is a liquid that is sprayed onto the surface of the mold to make separation of the mold and the cast part easier. Since carburetors have complex shapes, casting them requires copious amounts of release agent. And because heat from the mold and liquid metal changes the chemical structure of the release agent, it can't be reused. Consequently, used release agent is typically discarded as industrial waste.
  However, when Keihin started taking more precise measurements of waste to accelerate initiatives to reduce environmental impact, it realized that the amount of waste liquid that contained release agent was noticeably larger than that of other waste liquids. As motorcycle carburetor production expanded, release agent use and waste was also expanding. Left alone, this would only make Keihin's environmental impact—and the cost of processing waste—bigger and bigger. They had to do something to cut waste and costs. So, in 2001, Kato decided to attend an environmental trade fair in Tokyo to see if he could find a clue to solving this perplexing problem.
 "What I found there was a machine for making salt from seawater. We all know that heating seawater causes the water to evaporate, leaving behind salt. I thought, maybe we could use the same principle to process our waste liquid," said Kato.
 In his flash of inspiration, Kato immediately brought the idea to the people tending the booth. However, since their company had never used the machine to dehydrate large amounts of waste liquid containing mold release agent, they couldn't say whether it would work. So Kato suggested that Keihin lease the machine instead of purchase it.
 "I explained to them the merits of leasing from their own point of view. If our experiments worked, they would have a new sales channel, and without ever having to pay to conduct the experiments. That seemed to satisfy them, and they agreed to lease the machine to us for six months. The six months part is actually significant. I decided on six months because if we got the process to work during that time, we could estimate how many years it would take for us to recoup our investment. And that would make it easier to introduce the system."
 And so Keihin embarked on an unusual experiment to reduce waste liquid volume using a machine designed for making salt. The machine Keihin leased is called a disc dryer, and it works like this: A large round vertical disk is heated with steam and rotated slowly. Waste liquid is sprayed onto both sides of the disc, causing the water content in the liquid to evaporate and the leftover oil material (mold release agent) to stick to the disc at it rotates. The oil is then scraped off the disc with something that looks like a car wiper, and then discarded.
 But that's not to say that the development team used the machine successfully from the beginning. "We had trouble getting the results we wanted first, but after trying different types of waste liquids, we finally demonstrated that the process could work," said Takashi Otsuki, First Officerof the Environmental Conservation Section in the Environmental Conservation Department. "We later realized that the reason it didn’t work in the beginning was because the first waste liquids we tried weren’t chemically suited to being processed using the disc dryer."
 As a result, the team was able to reduce waste liquid volume by as much as the amount of water that the disc dryer evaporated, which today stands at 80% annually compared to FY2000, before the system was introduced.

Hitoshi Seino, Second Officer, Environmental Conservation Section, Environmental Conservation Department, Production Operations, Keihin Corporation

Hitoshi Seino, Second Officer, Environmental Conservation Section, Environmental Conservation Department, Production Operations, Keihin Corporation
Various waste liquids collect in this tank, where their constituents are separated using chemicals.
Various waste liquids collect in this tank, where their constituents are separated using chemicals.

Experience and skill become critical weapons in the fight to cut waste

 Keihin’s Kakuda Plant No. 2, located in Miyagi Factory No. 2, was built in 1973 and today manufactures electronic throttle bodies and air conditioner compressors for automobiles. Because the plant has different production lines and a different casting equipment setup from Miyagi Factory No. 1, it also produces a waste liquid unlike that of Factory No. 1. The main difference is that all of Miyagi Factory No. 2's liquid waste—mold release agents and various other chemicals—are collected in a single tank within the factory, which means they all end up getting mixed together. This made the search for a custom processing method take significantly longer, said Hitoshi Seino, Second Officer of the Environmental Conservation Section, who manages waste processing.
 "First, we tried to use the same disc dryer as Factory No. 1, but we didn't get very far because the liquid had so many different chemicals in it. Then we tried filtration, but had little success. Eventually we came to demulsification, which is a way of separating oil and water using chemicals. Even then, it took us about two years from the time we started testing demulsifiers until we understood exactly how to use them."
 The procedure for carrying out demulsification is surprisingly simple: Add chemicals to the tank of waste liquids, wait for the water and impurities to separate, and extract the impurities. However, since the properties of the chemicals in the waste liquid varied significantly depending on the manufacturing processes that were conducted that day, finding the right chemicals to separate the waste liquid into its constituents proved mind-boggling.
 "We sent information about our waste liquids to chemical companies and asked them to test chemicals that seemed appropriate. We then did our own tests based on their results. We did that over and over and over again. It was a long list of chemicals we went through," said Seino.
 As this painstaking work proceeded, the team also started gathering the hardware. But instead of spending money to install the latest product, they decided to make everything themselves—or as Kato put it, "Use our brains, not more stuff." The first contraption they made was small, with a processing capacity of only about 300 liters, built from a tank that was sitting in a corner of the plant. Through various tests, they gradually improved the unit, eventually reaching the third-generation unit with a processing capacity of two tons. It was 2010 when they finally put their system into operation. They soon found out that the most difficult part of this method is chemicals management.
 "The quality of the waste liquid that flows into the tank changes from day to day and is never the same," said Seino. "Separating it properly every time requires making precise adjustments to the amount of chemicals. Since you can't decide how much to use without actually looking at the waste liquid, the only guidelines we can set are ones that give a range instead of a specific amount, like 'Use two to four liters.' Those decisions have to be made by the person doing it."
 Kiyono and crew had entered the world of the craftsman, where experience and intuition makes every bit of difference. Using the wrong amount of chemicals could throw off process off balance, resulting in a larger amount of sludge to dispose of, and therefore higher disposal costs.
 "This isn't a job just anyone can do," explained Kato. "The two associates we chose had worked in wastewater treatment before, which uses chemicals. Also, producing a waste effluent means you have to follow certain wastewater quality standards, so we had to give this work to someone who could take responsibility for the results."
  According to Kato, only one person besides Kiyono could perform this important task perfectly. Passing on this skill—and the responsibility that comes with it—to the next group of associates will no doubt be a challenge they will have to face someday.

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