Chemical disinfection of combined sewer overflow waters using performic acid or peracetic acids

Abstract

Highlights Performic and peracetic acid disinfection of combined sewer overflow was evaluated  Sewer overflow water for laboratory studies was made with diluted raw wastewater  The bathing water indicator E. coli was always easier to disinfect than Enterococcus  Peracetic acid required long contact time (2 ppm, 6 h) for efficient disinfection  Performic acid was short lived but potent, efficient disinfection by 2 ppm, 20 min Abstract We investigated the possibility of applying performic acid (PFA) and peracetic acid (PAA) for disinfection of combined sewer overflow (CSO) in existing CSO management infrastructures. The disinfection power of PFA and PAA towards Escherichia coli (E. coli) and Enterococcus were studied in batch-scale and pre-field experiments. In the batch-scale experiment, 2.5 mg·L -1 PAA removed approximately 4 log unit of E. coli and Enterococcus from CSO with a 360 min contact time. The removal of E. coli and Enterococcus from CSO was always around or above 3 log units using 2-4 mg·L -1 PFA; with a 20 min contact time in both batch-scale and prefield experiments. There were no toxicological effect measured by Vibrio fischeri when CSO was disinfected with PFA, a slight toxic effect was observed on CSO disinfected with PAA. When the design for PFA based disinfection was applied to CSO collected from an authentic event, the disinfection efficiencies were confirmed and degradation rates were slightly higher than predicted in simulated CSO.Keywords: disinfection, combined sewer overflow, peracetic acid, performic acid; chemical disinfection; stormwater treatment, Escherichia coli, Enterococcus. 2 1.0 INTRODUCTION Combined sewer overflow (CSO) is a well-known phenomenon in combined sewer systems where wastewater and rain water are transported in the same sewers. CSOs occur when the rainfall exceeds the design capacity of sewer systems and needs to be discharged to surface water near cities, either directly, or after a short retention in detention tanks or outfall pipes (see graphical abstract, supplementary Figure S1). Discharge of untreated CSOs deteriorates the quality of receiving waters, since CSOs contain a variable mixture of rain water, raw sewage, watershed runoff pollutants, variable pathogenic organisms, viruses, cysts, suspended solids, chemicals and floatable materials (USEPA, 1999). In recent years, the effect of CSOs on water bodies used for recreational purpose has caught a lot of attention in Europe. Particularly the dedication from 2002 of Copenhagen harbor for recreational purposes including swimming and water sports has yielded an economically significant added service and tourism industry to the harbor area. Corresponding economic loss when CSO events close the harbor for bathing has inspired construction of significant retention basins which should limit the CSO events frequency, but due to the climate change related increased number of extreme rain events in 2000-2011 20, rain events caused temporary closing of the bathing (NYC Global Partners, 2011).According to European Un...

Treatment of Arctic wastewater by chemical coagulation, UV and peracetic acid disinfection

“…Phosphate, and suspended solids were determined according to standard methods (APHA, 2012) and using Hach Lange test kits in the laboratory at Department of Environmental Engineering, Technical University of Denmark. PAA concentration was analyzed using the colorimetric method described by (Chhetri et al, 2014) based on selective oxidation of ABTS by PAA without interference from hydrogen peroxide.…”

“…Residues of PAA were neutralized in laboratory experiments by adding 100 mg/L sodium thiosulphate to destroy PAA, followed by 50 mg/L catalase to destroy hydrogen peroxide (Wagner et al, 2002). E. coli was enumerated using Colilert-18 methods and Enterococcus were enumerated using the Enterolert methods from IDEXX (IDEXX laboratories, Maine, United States), as described by Chhetri et al (Chhetri et al, 2014). Heterotrophic microorganisms were enumerated by using direct plate count method as described in the standard methods (APHA, 2012).…”

“…From the stock solution, a working solution of 1 g/L PAA was made, which was quantified daily by dilution of subsamples to 2 mg/L and analyzed using the colorimetric method described by (Chhetri et al, 2014) based on selective oxidation of ABTS by PAA without interference from hydrogen peroxide. In the experiments, three doses of PAA of 2, 6 and 12 mg/L were applied to disinfect coagulated wastewater.…”

“…Ozone is a very efficient disinfectant; however, the sophisticated technology to generate ozone makes it unsuitable for disinfection of wastewater in the Arctic region. Organic peroxide, peracetic acid (PAA) is a strong disinfectant with a wide spectrum of antimicrobial activity, which was introduced to wastewater treatment approximately 30 years ago (Antonelli et al, 2006;Baldry, 1983;Falsanisi et al, 2006;Kitis, 2004;Koivunen and Heinonen-Tanski, 2005;Luukkonen et al, 2015) and recently it has been used to disinfect combined sewer overflows (Chhetri et al, 2016(Chhetri et al, , 2014. Commercial PAA is available as an acidic quaternary equilibrium mixture of PAA, hydrogen peroxide, acetic acid, and water:…”

Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO 2 ) and their by-products hydrogen peroxide (H 2 O 2 ) and chlorite (ClO 2 − )

“…They do not generate toxic by-products (Chhetri et al, 2014;Liberti and Notarnicola, 1999). Commercially available peroxycarboxylic acids are always available as a mixture of the peroxycarboxylic acids, hydrogen peroxide and corresponding carboxylic acid.…”