Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) reduction by granular zero-valent iron in continuous flow reactor

Wastewater streams containing hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are subject to regulatory discharge regulations that require processing through industrial waste treatment. Thus, the development of easy-to-apply technologies for the treatment of RDX-laden wastewater streams is imperative. In the present study, the reduction of RDX by granular zero valent iron (GZVI) in batch and column experiments was investigated. Preliminary batch tests conducted under both oxic and anoxic conditions showed that after 3.0 h of reaction with GZVI, RDX was mainly converted to formaldehyde (CH₂O), nitrate (NO₃ ⁻), and ammonium (NH₄ ⁺). Column filtration tests showed that pretreatment of the GZVI media with acid wash and low influent pH (4.0 ± 0.1) achieved 99% removal of RDX up to 5000 bed volume. BOD tests carried out on the post-treatment streams showed increased biodegradability of the treated wastewater, leading to a lower environmental impact for the final waste.