Click here to enlarge image"This system is just so much simpler," said that mill's environmental engineer. "And faster. That's why we chose it – because the equipment can reduce more BOD than conventional aeration, and Praxair can install it within three to four days of when they get the purchase order. I was looking for speed, and they hustled."
He explained the situation: "I produce 20,000 pounds of BOD a day. When an excursion occurs, you have to move fast. Before, I would rent expensive mechanical aerators that are labor-intensive to set up. In this situation, I would have needed 12-13 aerators, at 75 hp each, plus the generators to run them. I would have had to find a place to put the generators, and I would have had to bring in a diesel truck to fill them. It would have been two weeks just to set up. With these units, I issued a purchase order on Thursday, I was feeding oxygen by the next Thursday, and I was back to a comfortable BOD rating in two weeks."
Even More Speed
Mills manage living waste treatment systems that aren't predictable in their responses to weather and other factors. Often, unexpected things occur. That was the situation with the third mill.
This integrated pulp and paper mill had undergone some changes, and suddenly saw an elevated waste load. They needed a fast fix while they were diagnosing the problem.
"Their response time was tremendous. I called on Thursday, and they were in on Friday. The system was operating by the following Thursday," said the facilities manager at the third mill.
"We took two aerators offline and put two units in a five-acre section of our 1,000-acre wastewater treatment system. We then had seven times as much oxygen going in. We measured the dissolved oxygen (DO) in the pond before we put in the units and it was 0.50 parts per million. After the units were up and running, that five-acre area was saturated, with 10-12 parts DO per million."
Conclusion
Rapid response, immediate BOD reduction, simplicity and cost effectiveness are making In-Situ Oxygenation a preferred solution at paper and pulp mills that want to maintain full, uninterrupted production all year round – whether confronted by a sudden emergency or routine maintenance event.