Effects of Nitrosation on the Formation of Cyanide in Publicly Owned Treatment Works Secondary Effluent

Abstract

Cyanide has been detected in the effluents of some publicly owned treatment works (POTWs) at levels exceeding the influent concentration. The presence of nitrite ion (NO2− as a common constituent in domestic wastewater effluents may play an important role in the formation of cyanide through reaction with certain kinds of organic compounds, especially aromatic compounds. Laboratory studies with seven organic compounds (aniline, p‐toluidine, phenol, 1,2,4‐trihydroxybenzene, L‐serine, glycine, and benzoic acid) revealed that cyanide can be formed by reaction of nitrite with some of these compounds. The most substantial free cyanide (HCN, CN−) production observed at 25°C was 0.15 mg/L from reaction of 0.01 mM 1,2,4‐trihydroxybenze with 5 mg/L nitrite for 72 hours. Substantial free cyanide formation was also observed at pH 2‐4 in experiments with POTW effluents when reactive organics and nitrite were both added to wastewater. Formation of cyanide through nitrosation was strongly pH dependent, being most significant at low pH (2 to 4) and negligible at neutral‐to‐high pH. This result points to nitrous acid (HNO2) as being more reactive than the dissociated NO2− ion. The reaction of these nitrite species with organics also occurs in conventional analyses for total cyanide which involve distillation under strongly acidic conditions. Sufficient sample pretreatment with sulfamic acid at the time of sampling, not at the time of analysis, is highly recommended to prevent biasing analytical measurement of total cyanide in POTW effluents.

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).…”

Cyanide Formation and Fate in Complex Effluents and Its Relation to Water Quality Criteria: Results From a Three-Year Werf Study

“…Third, experiments were performed to evaluate the potential formation of cyanide from the nitrosation process, i.e., reaction with nitrite (Zheng et al, 2003e). The presence of nitrite ion as a common constituent in domestic wastewater effluents may play an important role in the formation of cyanide through reaction with certain kinds of organic compounds, (e.g., 1,2,4-trihydroxybenzene).…”