The Journal of Cleaner Production published a research that focuses on the development of the method that removes three times the amount of lead from biosolids compared to conventional means. This method could reduce the total cost of processing by more than 60%, allowing more people to live with clean water and soil.
The solid waste left over after sewage treatment is called biosoilds. A team of researchers from Florida State University has found a new inexpensive way to remove toxic heavy metals from biosolids. According to Gang Chen, a professor of Civil & Environmental Engineering at the FAMU-FSU College of Engineering, biosolids are a valuable resource, but heavy metals prevent their use.
More biosolids are being produced as the human population of the planet grows and more people move to cities. In some countries, about half of all biosoilds are recycled and being used as an ingredient in fertilizer in agriculture. An obstacle to the safe use of biosolids is the presence of potential toxins that can leach into the environment. Therefore, before disposal or recycling can happen, it’s important to first extract the heavy metals, which can be expensive. The team from Florida State University is developing a more efficient extraction process. They turned to their knowledge of energy to develop the method. They calculated the amount of energy that was needed to break the bonds that attached the heavy metals to the rest of the biosolid but would not destroy the biosolid itself. Somewhere on the electromagnetic spectrum, Chen’s group found the radiation with the right amount of energy. Microwave radiation seemed to be just right. After treatment in a microwave, researchers were able to remove the heavy metals from biosolids with a lower dosage of treatment chemicals than traditional extraction requires.
This technique offers a less expensive way to make biosolids safe.
Developing this method is very important, because if heavy metals remain in biosolids that are applied to soil, those metals can be absorbed by plants, which become part of the food chain for animals or humans. As they accumulate in the body, they can cause intellectual disability in children, dementia in adults, central nervous system disorders and damage to organs.
The members of the team that contributed to this study are former doctoral student Simeng Li, a current assistant professor in the Department of Civil Engineering at California State Polytechnic University, Pomona, Runwei Li, a doctoral candidate in the FAMU-FSU College of Engineering, and Youneng Tang, an assistant professor of Civil & Environmental Engineering in the FAMU-FSU College of Engineering. This research was supported by the Hinkley Center for Solid and Hazardous Waste Management.