Making chlorine greener: investigation of alternatives to sulfite for dechlorination

Evaluation of Dechlorinating Chemicals for Spent Membrane Cleaning Solutions

“…There is little information on the effect of dechlorinating chemical dosage on the rate or extent of the reaction when dealing with the elevated chlorine concentrations that are typical of spent cleaning solutions. Most reports (Basu and De Souza, 2011;Bedner et al, 2004) have addressed dechlorination of more dilute solutions such as drinking water or treated wastewater. It was anticipated that the conditions associated with dechlorination of spent cleaning solutions would differ substantially from those present when dechlorinating final effluents.…”

“…The presence of organic matter has been shown to reduce the rates of dechlorination reactions in dilute solution (Basu and Desousza, 2011). In addition, the rates of dechlorination reactions have been reported to be pH sensitive (Bedner et al, 2004). The reaction between a number of the dechlorinating agents and chlorinated compounds are known to have an effect on the concentrations of acids (HOCl, HCl) and bases (NH 3 , NaOH) in solution (AWWARF, 2001).…”

Disinfection and Antimicrobial Processes

“…In a study for alternative agents for residual chlorine reduction, ten agents were used with the following four model compounds for a simulation of chloramines typically found in municipal wastewaters: an inorganic chloramine, a secondary organic 1433 chloramine, and two peptidic chloramines. The most promising alternative agents were thiosulfate, Iron (Fe) metal, and iodide-mediated sulfate (Bedner et al, 2004).…”

Kinetics of tap water dechlorination and aquatic health impacts of selected dechlorination chemicals

“…Commonly known as vitamin C, L-ascorbic acid (C5H5O5CH2OH) is widely used to dechlorinate water for medical (e.g. kidney dialysis units) (Wiseman, 1997) and analytical purposes (Bedner et al, 2004) During the above reaction, hydrochloric acid is produced reducing the solution pH. The AA solution itself has a pH of 2, which is highly corrosive (EC, 2003).…”

“…Together, the above factors could substantially reduce the pH of the AA reaction solution. AA is effective in reducing both hypochlorite and chloramine (Paterka, 1998), but Bedner et al (2004) found the reaction rate of AA with chlorine to be much slower than that of sodium sulfite and thiosulfate. Although EC (2003) claims that AA is not a DO scavenger, Bedner et al (2004) found that it exerts a Biological Oxygen Demand (BOD) of 3.1 mg O2/L when reducing 1 mg CI2/L with a 50% molar excess of AA.…”