Formation of Free Cyanide and Cyanogen Chloride from Chloramination of Publicly Owned Treatment Works Secondary Effluent: Laboratory Study with Model Compounds

Abstract

The potential generation of cyanide species in wastewater upon chlorination in the presence of residual ammonia (resulting in chloramine formation) was investigated in experiments with synthetic solutions and publicly owned treatment works (POTW) secondary effluent. This study demonstrated that low concentrations (approximately 5 to 25 μg/L as cyanide) of cyanogen chloride (CNCl), a highly toxic cyanide species not measured in total or free cyanide analyses, could be detected as a result of chloramination reactions in POTW secondary effluent. The potential for chloramination of nitrogen‐bearing organic compounds to yield CNCl and/or free cyanide was demonstrated in experiments with synthetic solutions spiked with selected precursor organics: L‐serine, benzene, catechin, and humic acid. The amino acid L‐serine yielded the largest concentrations of CNCl upon chloramination. Additionally, detectable cyanide (approximately 10 μ/L) was observed in solutions of L‐serine and in POTW secondary effluent that was chloraminated followed by dechlorination to prevent destruction of any free cyanide produced. Thus, chlorination of POTW secondary effluent containing residual ammonia can lead to chloramination of organic compounds and the resulting production of CNCl and free cyanide.

Wastewater-Derived Dissolved Organic Nitrogen: Analytical Methods, Characterization, and Effects—A Review

“…In addition to acting as a precursor for THMs and DHAAs, which are regulated disinfection by-products (DBPs), wastewater-derived DON may form a variety of DBPs that contain a nitrogen functional group (i.e., haloacetonitriles [HAN] Bieber and Trehy, 1983;Oliver, 1983;Trehy et al, 1986;Ueno et al, 1996;Reckhow, 2003;cyanogen halides [CNCl], Hirose et al, 1988;Pedersen et al, 1999;Zheng et al, 2004aZheng et al, , 2004bZheng et al, , 2004cand N -nitrosodimethylamine [NDMA], Sedlak, 2002, 2004;Mitch et al, 2003). Furthermore, wastewater-derived DON affects the efficiency of chlorination and dechlorination processes.…”

Factors Affecting Cyanide Generation in Chlorinated Wastewater Effluent Matrix

“…The mechanism of cyanide and CNCl formation from glycine in water under free chlorine conditions has been reported by Na and Olson (2006). Monochloramine has been shown to react with formaldehyde and eventually yield HCN (Pedersen et al, 1999); organocyanide compounds (cyanocobalamin and coenzyme vitamin B12) release free or metal-complexed cyanide upon chlorination (Yi et al, 2002); solutions of L-serine that were chlorinated and subsequently dechlorinated were shown to produce cyanide (Zheng et al, 2004a); reaction of nitrite with aromatic compounds can produce cyanide (Zheng et al, 2004b); microorganisms have been shown to be capable of producing cyanide (Brandl, 2005); less than stoichiometric chlorination of thiocyanate can liberate free cyanide (Zheng et al, 2004c); and, it was found that phenol reacts with nitrous acid to produce cyanide ions (Adachi et al, 2003). The potential for chloramination to yield cyanide from organic compounds was demonstrated in earlier experiments using synthetic solutions spiked with select precursor organics such as ascorbic acid, humic acid, D-ribose, and 2-furaldehyde (Carr et al, 1997).…”

Change in genotoxicity of wastewater during chlorine dioxide and chlorine disinfections and the influence of ammonia nitrogen

“…Choi [15] pointed out that chloramines could produce N-nitrosodimethylamine as a DBP. Zheng et al [16] reported that chlorination of publicly owned treatment works…”