by Azita Yazdani, Exergy Technologies
Besides critical uses of water for human consumption, such as drinking, showers, washing clothes, etc., there are many uses of water that do not require fresh supplies. This is particularly true in many industrial and high tech manufacturing uses such as printed circuit boards (PCB), solar, disk drive and semiconductors. High tech fabs and other manufacturers use hundreds and thousands of gallons of fresh water and materials per minute, 24 hours a day, and 7 days a week. Reuse and recycling is the most economical and environmentally responsible way to use existing materials and water supplies wisely. By reducing water consumption, we can make sure of continued resources availability and keep our cost and many of our compliance issues at bay.
Many ask, why worry about water and its availability? Water is available to all, cheap and plentiful, and they are established methods to store, deliver and treat water and wastewater. The problem is that in many parts of the world water is scarce, and polluted. And this matter can get further complicated with population growth, aging infrastructure, and global warming dangers. In some instances we have also reached the limit of our water and other material resources and the costs are rising. In short, business as usual cannot continue. We need to find new ways of thinking about water and materials.
While water efficiency measures such as countercurrent rinsing, are a part of our progress toward improving uses of water, over 2/3 of water used in industrial and urban settings can be saved with onsite recycling technologies. There are many ways to look at water efficiency and conservation, but the most important question to answer is how this can be achieved sustainably and cost effectively.
Point of use recycling
High tech manufacturing processes are considered to be a ‘brown’ manufacturing process. Large volumes of materials and resources such as DI water are disposed after one use as waste or wastewater. The factories that install such processes dispose this waste offsite or treat them onsite after generation, at a high cost to them and to the environment. A better solution would be to keep these resources clean and re-purify and recycle onsite, at the point of use (POU) to eliminate the need to waste management onsite or offsite, and to eliminate the need for new materials and resources.
Exergy is a U.S. based technology company that is in the process of deploying several recovery and recycling technologies for miscellaneous wet manufacturing processes. These technologies allow recovery and recycling of high purity water, and materials, such as acids, commonly used in a number of wet manufacturing processes. The concept of ‘closed-looping’ of industrial processes will create a wet process line that is a ‘green’ line and completely eventually closed-looped.
Wet process chemistries
In most fabricated wet lines (by the various companies who offer these lines), the wet process chemistries are followed by rinses. These rinses are normally designed to be running wet lines, and the flow and use of water (and materials) is continuous. Additionally, the chemistries used in these processes are commonly disposed after certain mount of parts are processed or by hours of operation or continuously due to contamination or dirt build up as well as chemical decomposition. The results of which become hazardous waste streams that has to be managed normally off site or on site with a high cost for treatment.
EthorCEL, an internationally patented point of use water purification and recovery technology, for high purity water, produces high quality recycled DI water using membranes and electricity, instead of conventional ion exchange or reverse osmosis technologies alone. EthorCEL easily adapts to many process applications, is environmentally clean and safe, operates automatically, does not require any regeneration chemicals or bottle exchanges, such as IX, and has proven to provide for a fast paybacks of 1-3 years for most customers.
The purification of the materials and resources such as water results in avoidance of the disposal after one use, and thus the need for water and waste treatment onsite or offsite, ultimately allowing for ‘indefinite and continuous’ reuse of material and resources. This approach, which today is an anomaly, allows manufacturing customers to reduce cost of production substantially. It eliminates the continuous consumption cycle and replaces it with the complete realization of material efficiencies.
Cost of point of use recycling
Many of us are still under the impression that recycling is expensive. Recycling rinse water is generally perceived to be more expensive than ‘treat and discharge’ and conventional wastewater treatment/precipitation approaches.
While the costs of water and sewer have substantially risen in the past decade, it is still cheap to buy water and in some places dispose of wastewater. However, when one looks closely at the cost of water and sewer, and adds the water pre-treatment, and wastewater treatment costs the pictures really reveals itself.
Exergy has conducted numerous cost/benefit analyses across the country, collecting data from many customers to see if recycling pays back; and we have to say it does, indeed!! The various site data have shown that recycling of rinse water in manufacturing processes, with the EthorCEL, as an example, offers superior water quality across the board for many customers, and saves over 70% of customers current cost of operation or cost of ownership (COO).
What does this mean? It means that recycling has a huge cost saving and payback if the choice is made to purchase equipment. This also means that normal customers should be able to payback a recycling system within one-three years after acquisition, depending on their current internal costs, as well as volume/flows, features, and performance they expect from a recycling process.
A case study
Facility A is a large printed circuit plant, which uses about 30 gallons per minutes of water in its various processes. The company was interested to evaluate the possibilities of water recycling for part of its operations. After close evaluation of the plant current cost, the data showed the cost of recycling vs. customer’s current cost of operation (or cost of ownership) is much lower, by about 70%.
Water as well as the array of rare earth minerals and material specified for use in high tech manufacturing industries is scarce and expensive. The use and process efficiencies and point of use recycling, can achieve cost reduction and resource conservation by integrating recovery and reuse technologies. These technologies will help future manufacturing processes to stay green. The desire of manufacturers to secure unlimited water resources is unattainable. Water reuse, however, goes a long way to fulfill this goal.