Researchers at the University of Illinois Urbana-Champaign have demonstrated a promising new approach to wastewater treatment using a combination of woodchip bioreactors and a specialized designer biochar. The study, published in the Journal of Hazardous Materials, tackles two pressing water-quality challenges: nutrient pollution and pharmaceutical contaminants.
Lead author Hongxu Zhou explained that pharmaceuticals and personal care products (PPCPs), even at low concentrations, pose significant risks to water quality, ecosystems, and public health due to their potential to disrupt biological processes and promote antibiotic resistance. While nutrients like nitrogen and phosphorus are well-known culprits in creating visible problems such as algal blooms, PPCPs threaten water systems in more subtle but potentially damaging ways.
Zhou emphasized the urgent need for wastewater management solutions to address both challenges.
Woodchip Bioreactors and Designer Biochar Approach
The research team built on the well-established effectiveness of woodchip bioreactors—structures that harness microbial communities to break down nitrate into nitrogen gas. To complement this, they developed a new form of biochar using sawdust pretreated with lime sludge and then slow-burned to create a highly porous material capable of binding phosphorus and pharmaceuticals.
The team tested this combined system, referred to as the B2 system (bioreactor-biochar), by introducing contaminated water containing a mix of nitrogen, phosphorus, ibuprofen, naproxen, sitagliptin, and estrone. Water passed through the woodchip bioreactor and then through biochar-filled tubes, achieving significant removal rates: 77% of nitrate, 99% of phosphorus, and 70%-97% of various pharmaceuticals.
Key Findings and Engineering Implications
Wei Zheng, a co-author and principal scientist at the Illinois Sustainable Technology Center, noted that the biochar acted much like activated carbon, efficiently capturing pharmaceutical residues. The team also explored different water flow speeds and biochar formats (granules versus pellets), finding that slower flow rates enhanced nitrogen removal and granules captured more pharmaceuticals and phosphorus.
The researchers observed minor changes in bacterial communities within the bioreactor, but the overall nitrate removal efficiency remained stable. This robustness suggests that the B2 system can maintain its effectiveness even in real-world conditions where PPCPs are present.
Potential for Industrial Applications
While this study was conducted at the laboratory scale, the team also modeled the system's scalability, indicating potential applications for larger, industrial-scale water treatment processes. By combining microbial treatment with biochar filtration, the B2 system offers a versatile and effective way to tackle multiple contaminants simultaneously, pointing to promising advances in wastewater treatment technology.
This research highlights how combining innovative filtration techniques with microbial processes can create a more comprehensive and resilient approach to water quality management, offering engineers new tools to address complex contamination challenges.
