Control of Pre-formed Halogenated Disinfection Byproducts with Reuse Biofiltration

Area of Science:

• Environmental Science
• Water Treatment Technology
• Microbiology

Background:

• Prechlorination in drinking water treatment generates harmful disinfection byproducts (DBPs).
• Effective control strategies for pre-formed DBPs, especially non-regulated toxic species, are lacking.
• Biofiltration is explored as a potential method to mitigate pre-formed DBPs.

Purpose of the Study:

• To evaluate the biodegradation potential of pre-formed DBPs during biofiltration.
• To assess the removal of haloacetonitriles (HANs), haloacetamides (HAMs), and haloacetaldehydes (HALs).
• To determine the efficacy of biofiltration in reducing DBP concentrations and toxicity under potable reuse conditions.

Main Methods:

• Biofiltration using sand, anthracite, and biological activated carbon.
• Treatment of three wastewater effluents under potable reuse conditions.
• Monitoring of DBP concentrations and associated biodegradable organic carbon.

Main Results:

• Over 90% removal of di- and trihalogenated HANs, HAMs, and HALs was achieved.
• DBP removal was linked to active heterotrophic biomass and biodegradable organic carbon reduction.
• Biofiltration reduced total DBP concentrations from 271 μg/L to 22 μg/L, a 96%+ reduction in calculated toxicity.

Conclusions:

• Biofiltration demonstrates significant promise for controlling pre-formed DBPs, including toxic species.
• A biologically mediated hydrolysis pathway, not microbial dehalogenation, appears responsible for HAN and HAM removal.
• Biological activated carbon also contributed to controlling trihalomethanes through adsorption.