20 Sep 2018
A process invented at UW-Madison now removes phosphorus at the Madison Regional Wastewater Treatment Plant. Like many other advances from colleges of agriculture and engineering, this one is designed to reduce the costs and environmental consequences of wastewater treatment.
The system, designed by soil science professor Phillip Barak, focuses on reducing releases of phosphorus, a plant nutrient that fuels algal blooms in lakes and streams. The system can also improve the flow of pipes in the Madison Metropolitan District Sewerage Treatment Facility (MMSD) by reducing the build-up of phosphorus compounds.
Barak’s Nutrient Recovery and Recycling (NRU) pilot project manages about 5 to 10 percent of the throughput of the processing plant and creates 200 pounds of brushite (a solid fertilizer) per day.
It is seldom a topic at the table, but civilization fails without sewage treatment. In the Madison area, the flush ends at the district headquarters south of the belt line. Here, large pools containing countless numbers of microbes break down the complex molecules. In a few days, the pathogens are neutralized, the liquid fertilizer is ready to be injected into the agricultural fields, and a stream of clear, disinfected water flows to the Rock and Sugar rivers.
The relationship between the Sewer District and the University of Wisconsin is at least 90 years old, says district chief engineer Michael Mucha, and it started with methane, a gaseous byproduct of the microbial digestion process. “We have an article from a 1930s Wisconsin State Journal article that reported that engineers at power plants attending college ate hamburger sandwiches cooked over a sewer gas flame using a new entrapment method. gas, ”explains Mucha.
Today, the plant burns enough methane to provide one-third of its electricity.
“UW-Madison has always been there for us with their expertise, and we have given back by offering practical knowledge in management, technology and leadership. “
MMSD District Chief Engineer Michael Mucha
“It’s been a transparent relationship,” adds Mucha. “UW-Madison has always been there for us with their expertise and knowledge to help us with our projects. We gave back by offering a working knowledge of management, technology and leadership. Our collaboration has supported student learning, advanced technology, recognized the human element of change, and made the factory safer, cleaner and more efficient.
Over the years, a revolving door between the neighborhood and the University has benefited both sides. For example, Professors Paul Mac Berthouex, Edward Schten and Lawrence Polkowski have long served as District Commissioners.
Ned Paschke, now part of the engineering college’s professional development department, served as the district engineering director for 18 years. Paschke notes that the district adopted ultraviolet (UV) disinfection for wastewater in the early 1980s, with guidance from UW-Madison leaders and former engineers, including Jim Nemke, Paul Nehm and Jon Schellpfeffer. “The idea was to replace chlorine, which can lead to serious health and safety issues,” Paschke explains. “When the district installed the new UV system, it was the largest of its kind in the world, and people came from all over the country and the world to observe the system.”
The story, Paschke says, “is a prime example of technology and engineering science being used for the benefit of the public.”
A second district pilot project aims to reduce the amount of oxygen needed by microbes during treatment. The project is led by Daniel Noguera, a professor of civil and environmental engineering who says he started exploring how bacteria break down ammonia about 15 years ago. “Even though the manual said it would never work, I started to wonder if some microbes could break down wastewater to lower oxygen levels.” Working with samples from the processing plant, his lab proved the impossible, leading to a process requiring only a tenth of the usual oxygen level.
Testing at the district pilot plant could be a big money-saver, Mucha says, since the fans used to supply air to the treatment process are the district’s biggest electrical load.
“The issues I’m trying to resolve with the district are issues of practical importance to them,” says Noguera, “but from a university perspective, these collaborations allow us to train our students and address issues. more scientific questions. What organism is doing this decomposition, and why does it work this way? “
Dephosphatation: on the way to the national scene?
As the environmental damage caused by excess phosphorus becomes more apparent in the algae mats of lakes and streams, sanitation systems are called upon to tighten controls.
Support for technology development and the pilot plant came from the NRU, its business partner Centrisys / CNP, the National Institute of Food and Agriculture, United States Department of Agriculture, and the United States Department of Agriculture. Wisconsin SBIR Advance program. The District provided in-kind support.
Eventually, either the phosphorus extractor or the low oxygen process, or both, could become standard processes in wastewater services. This example – of UW – Madison’s contributions to successful technologies – appeared long ago in the district system for the recycling of solids remaining after processing. These biosolids are rich in organic matter, phosphorus and nitrogen, making them an ideal soil amendment for agriculture. The district biosolids program, known as Metrogro, manages the 5,000-acre application in Dane County and surrounding counties, paying close attention to application rates, soil type, condition of the ground and the slope.
In the 1980s, to address concerns about possible contamination with heavy metals like lead and mercury, UW-Madison soil specialist Art Peterson began testing how these metals moved from soil to crops. and came to a counterintuitive conclusion: applying the solid residue, then called “mud”, would reduce the uptake of lead in plants, possibly due to the improved microbial environment in the soil.
A program like Metrogro, which solves an inevitable problem in the district while improving soil health, water retention and crop yields, demonstrates a new way of seeing the role of the district, says Mucha. “We are moving away from the public perception that wastewater is a bad thing – that you drain it and it goes away – to see it as water containing renewable resources that can be reused for society. . Already, 99.9% of what comes in is reused. We create clean water that is returned to the environment, recover three different forms of nutrients that are used for agricultural production, and we create renewable energy. In many ways, we are in the food, water and energy business. It is a complex task, a multidimensional balancing act, and to accomplish it we welcome our long-standing partnership with UW-Madison.
Dave Tenenbaum | University communication