AEESP Spotlight: Mid-2023

The “spotlight” column draws attention to selected articles in Environmental Engineering Science (EES), the official journal of the Association of Environmental Engineering and Science Professors (AEESP). Spotlight articles appear three times per year in the journal as well as in the AEESP newsletter. Through the publication of high-quality peer-reviewed research, the EES journal helps AEESP achieve its mission of developing and disseminating knowledge in EES. In this entry, we shine the spotlight on selected articles from the December 2022 to March 2023 issues of EES. Congratulations to all whose work is highlighted.

Some plastic materials can be problematic for the environment and society because of pollution created during their manufacture and because of the need for proper end-of-life disposal. Interestingly, many of the devices we use to clean air and water (and thus improve the built and natural environment) are themselves made of plastic components (which may cause harm). Polymeric membranes are a class of materials that often require toxic solvents during manufacture and then are difficult to recycle or degrade after disposal. Wan et al. (2022) took a step toward more sustainable polymeric membranes by using chitosan as the base material.

Chitosan is derived from shrimp and other crustacean shells, and is more biodegradable than many petrochemical-derived polymers. It was formed into a membrane using an aqueous alkaline/urea solvent, which is safer than many other solvents. The chitosan membrane flux and fouling performance were less than desirable, but modification with dopamine and tannic acid improved its performance in separating an oil emulsion from water. Although still not capable of water fluxes as high as commercial membranes, the chitosan membrane boasts the benefit of being more environmentally friendly and may be cheaper to produce. The stage is set for further development of this promising technology.

Disinfection is a pivotal procedure safeguarding human and animal health. Recent research has shown that certain RNA viruses and bacteriophages can evolve to develop increased resistance to common disinfection methods such as free chlorine and thermal treatment. Zhao et al. (2022) expanded our knowledge about the adaptability of DNA bacteriophages to these same processes using T7 coliphage as a representative species. Batch assays with consecutive exposures to thermal treatment revealed increased resistance as compared with the unexposed strain.

This was not the case for parallel tests exposed to free chlorine, suggesting that chlorine-based disinfection may be more reliable than previously thought for inactivating certain types of bacteriophages. Although T7 coliphage has traditionally been used as an indicator for enteric viruses in water treatment processes, its adaptability to thermal treatment challenges the suitability of using T7 and other somatic coliphages as sole viral indicators and surrogates for human pathogens in water treatment and other processes.

On one hand, disinfection can eliminate microbial pathogens and purify water. On the other hand, this process may produce unintended chemicals, namely disinfection by-products (DBPs), which may pose negative ecological and health effects. Brominated DBPs are of particular concern given their potent toxicity and lack of control measures. Through data mining with nationwide water quality surveys, Weisman et al. (2023) investigated the occurrence of two important brominated DBP precursors, bromide and total organic carbon (TOC), in public water system (PWS) source waters. Particularly, surface water sources in multiple Midwestern and western watersheds (e.g., Texas-Gulf and Rio Grande watersheds) had a combination of elevated bromide and TOC, raising the possibility of brominated DBP formation and thus risk to drinking water consumers in these regions.

Temporal differences were also observed and can be attributed to the influence of climate change and other anthropogenic effects. The study highlights the need for PWSs to consider source water type and the specific watershed characteristics when developing DBP control strategies. The findings of this study may also inform policy decisions related to water quality and safety regulations, and could potentially lead to changes in the way that PWSs monitor and manage DBP precursors in their source waters.