小蝌蚪APP

Stopping a Waste of Useful Waste

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Posted on January 23, 2020

Bob Lowry

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Let鈥檚 talk about sludge.

Through the wonderful process whereby your local water treatment plant takes wastewater and turns it into usable water, there鈥檚 a by-product of sludge left behind.

鈥淭ypically,鈥� said Dr. Arka Pandit, an assistant professor of civil, coastal and environmental engineering at the 小蝌蚪APP, 鈥渢his sludge, which has been treated with aluminum sulfate, is dewatered and sent to the landfill, costing both money and resources.鈥� And in burying the sludge, something of value may be buried with it.

According to Pandit, the treated sludge 鈥� it鈥檚 technically known as SAS, which stands for spent-alum sludge 鈥� can contain phosphorus from wastewater, stormwater and agricultural runoff.

鈥淓utrophication (that鈥檚 when excessive nutrients in a body of water, often due to runoff from the land, cause a dense growth of plant life and death of animal life from lack of oxygen) is one of the biggest challenges of this time and, on top of that, one of its primary contributors, phosphorus, is a limited resource. So nutrient removal and recovery has enormous potential to address this two-pronged challenge,鈥� Pandit said.

The question is, how to get to the phosphorus?

Two engineering students at South have taken up the question, and together they are creating enough interest to generate some national attention.

Rachel Chai, who鈥檚 majoring in civil engineering, and mechanical engineering major Bryant Baldwin recently placed second in the country in a research competition sponsored by the American Society of Civil Engineers.

The competition asked university student teams to design 鈥渇orward-looking鈥� ideas that could transform the way civil engineers approach, design and build infrastructure, and create a feasible business model. Chai developed much of the research and Baldwin developed the proposal.

鈥淚 grew up by the coast and water has been a big part of my life,鈥� said Chai, who was raised in Ocean Springs, Miss. 鈥淭hrough the years, I have seen some detrimental effects which seem to have no solution. This drives me to continue to pursue this problem no matter how hard it is.鈥�

How hard is it?

鈥淗onestly, I'm a bit confused much of the time during this research,鈥� Chai smiled. 鈥淚t's been a lot of question asking and 鈥榦h, that's right鈥� moments.鈥�

Those questions and moments usually take place in the environmental engineering laboratories in USA鈥檚 Shelby Hall. It鈥檚 there where Pandit and Chai have collected the treated sludge, or SAS, from the Myers Water Treatment Plant in Mobile, and have used tests to see if the sludge could adsorb phosphate from synthetic wastewater and, if yes, to determine its capacity.

鈥淪he learned two things,鈥� Pandit said. 鈥淥ne, the SAS has the capacity of removing phosphate from wastewater, and two, it has a preference for phosphate over other ions commonly present in wastewater.鈥�

The experiments also revealed that there is negligible to no leaching of any other metals of concern from the sludge during this process, so the problem of eutrophication is addressed by not letting the phosphorus reach water bodies.

Practically as important as the research is the sharing of the findings. This is where Baldwin came in.

鈥淩achel pulled me in to coach her in her presentation,鈥� he said. 鈥淚 have experience in sales and had received training here at South in a special program called I-Corps, where I learned how to take a product or idea, mold it to fit the market and sell it. I do have a passion to sell products that I wholeheartedly believe in and when Rachel showed me her product, the importance of it and the big picture, I immediately supported it.鈥�

Baldwin, a graduate of Mobile鈥檚 Baker High School, helped her in preparing the poster and to run a couple of sets of experiments, the results from which were included in the poster and presentation at the national competition.

鈥淲e had several late nights and early mornings in preparation of our event,鈥� Baldwin said. 鈥淭he hardest part about it was that we had to work remotely. I was in South Carolina for the summer and Rachel was in Alabama. We had to do a lot of video calls almost every day to ensure we were well prepared and on the same page on everything before we presented.鈥�

The benefits of national recognition for the students are obvious, but Pandit said the long-term benefit for undergraduate students is getting engaged in research. 鈥淚t helps them to think more critically, think about the broader implications and be better equipped with tools to address a challenge,鈥� Pandit said. 鈥淪o, yes, this is invaluable indeed.鈥�

Chai and Baldwin are scheduled to graduate in May and both indicate they are leaning toward enrolling in graduate school.

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