According to the O’Neill report, the world’s annual costs of antibiotic-resistance bacteria or ARBs are expected to reach $100 trillion and 20 million deaths, mostly children under the age of 5, by 2050. Recent studies suggest the prevalence of the ARBs in our water systems has increased due to corroded pipes in the water distribution systems, discharge of the bacteria-contaminated wastewater into the rivers, and climate change-related epidemics. Due to increased bacterial resistance, conventional water disinfection technologies, including antibiotics, chlorination, and ozonation, are becoming cost-prohibitive and less effective in making water safe. Affordable wastewater disinfection technologies are urgently required to prevent the spread of ARBs through wastewater and reduce the disease burden.
Among existing water technologies, adsorption is the most cost-efficient, easy to use, and reusable technology. However, traditional adsorbents, such as activated carbon’s nanometer-size pores, easily get clogged with micrometer-size bacteria resulting in slow kinetics and costly regeneration. Furthermore, carbon cannot kill bacteria. To address this gap, we developed inexpensive sponge-based adsorbents to capture and kill pathogenic bacteria from the wastewater. A library of sponges was fabricated by coatings different aminosilane capped nanosilica onto the polyurethane sponges. Through materials and process optimization, two best candidates with outstanding biocompatible and biocidal properties were produced. The biocompatible sponges could remove common water-borne gram-positive (S. epidermidis, B. subtilis, S. mutans) and gram-negative (E. coli, P. aeruginosa, B. cenocepacia) bacteria from nutrient-rich water with 90-99% removal efficiency. At the same time, the biocidal sponge could kill the captured bacteria with an efficacy of 10⁴ to 10⁶ CFUs. The electron microscopy images suggested that bacterial death at the sponge surface was due to their membrane rupture or cell lysis. Due to the efficient capture and killing of the pathogenic bacteria, these sponges could emerge as the affordable solution to combat water-borne bacterial disease challenges.

Daryl R. Williams

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