Chlorination or monochloramination: Balancing the regulated trihalomethane formation and microbial inactivation in marine aquaculture waters

Abstract

Disinfection methods like chlorination are increasingly used to sanitize the water, equipment, tools and surfaces in aquaculture facilities. This is to improve water quality, and to maintain a hygienic environment for the well-being of aquatic organisms. However, chlorination can result in formation of regulated disinfection byproducts (DBPs) that can be carcinogenic and toxic. This study aims to evaluate if an optimal balance can be achieved between minimal regulated DBP formation and effective microbial inactivation with either chlorination or monochloramination for application in the Red Sea aquaculture waters. Upon chlorination, the concentration of total trihalomethanes (THMs), primarily bromoform, exceeded the regulatory limit of 80 µg/L even at the lowest tested concentration of chlorine (1 mg/L) and contact time (1 h). Comparatively, regulated THMs concentration was only detectable at 30 µg/L level in one of the three sets of monochloraminated marine aquaculture waters. The average log reduction of antibiotic-resistant bacteria (ARB) by chlorine ranged from 2.3-log to 3.2-log with different contact time. The average log reduction of ARB by monochloramine was comparatively lower at 1.9 to 2.9-log. Although viable Staphylococcus aureus was recovered from monochloraminated samples as opposed to chlorinated samples, the abundance of S. aureus was not high enough to result in any significant microbial risks. Both chlorination and monochloramination did not provide any significant improvement in the reduction of antibiotic resistance genes (ARGs). This study demonstrates that a systematic evaluation is needed to determine the optimal disinfectant required to balance both microbial and chemical risks. Compared to chlorine, monochloramine may be a more appropriate disinfection strategy for the treatment of aquaculture effluents prior to discharge or for recirculatory use in the aquaculture facility.

Optimizing Potable Water Reuse Systems: Chloramines or Hydrogen Peroxide for UV-Based Advanced Oxidation Process?

“…Our results also have broad implications for engineered, agricultural, food and natural systems, where chloramine exists. For example, chloramines are commonly used as disinfectants in households, commercial cleaning, and food and health industries. − Similarly, the widespread practice of chlorine-based disinfection of nitrogen-rich recreational water pools and agricultural waste streams (e.g., lagoons storing animal manure, animal waste, aquaculture effluent), − can lead to potential formation of chloramines in these waste streams. Furthermore, UV-based treatments of produced water, brackish groundwater, and desalination concentrate generate chloramine in the system. , The methodologies developed for trace organic contaminant degradation in this study are applicable to these chloramine- and halogen-impacted environmental- and engineered-systems.…”

Insights into antimicrobial agent sulfacetamide transformation during chlorination disinfection process in aquaculture water

“… 9 Residual antibiotics are degraded during the chlorination process; however, studies have found that antibiotics undergo side reactions with chlorine disinfectants to generate halogenated disinfection by-products (H-DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). 10,11 These H-DBPs have attracted extensive attention in the field of scientific research owing to the latent health risks. 12 In seawater, hypobromous acid (HOBr) can be generated by the chlorine oxidation to be dominant oxidant species, leading to preferential formation of various brominated by-products.…”

UV and bacteriophages as a chemical-free approach for cleaning membranes from anaerobic bioreactors

“…Physical cleaning is generally more effective for the reversible foulant layer (10), while chemical cleaning is used to remove irreversible foulant layers (11). However, the use of these chemicals can lead to the formation of carcinogenic and toxic byproducts, and can detrimentally impact the membrane integrity (12,13). In addition, it was shown that certain bacteria, such as Acinetobacter spp.…”