Implications of COD analysis use in the peracetic acid-based wastewater treatment (original) (raw)
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Chemical aspects of peracetic acid based wastewater disinfection
Water SA, 2014
Peracetic acid (PAA) has been studied for wastewater disinfection applications for some 30 years and has been shown to be an effective disinfectant against many indicator microbes, including bacteria, viruses, and protozoa. One of the key advantages compared to, e.g., chlorine is the lack of harmful disinfection by-products. In this paper a pilot-scale study of PAAbased disinfection is presented. Indicator microbes (E. coli, total coliforms and coliphage viruses) as well as chemical parameters (pH, oxidation-reduction potential (ORP), chemical and biochemical oxygen demand (COD and BOD), and residual PAA and hydrogen peroxide) were studied. The main aim of this investigation was to study how these selected chemical parameters change during PAA treatment. Based on the results, disinfection was efficient at C•t values of 15 to 30 (mg•min)/ℓ which equals to a PAA dose of 1.5 to 2 mg/ℓ and a contact time of 10 to 15 min. In this concentration area changes in pH, COD and BOD were negligible. However, hydrogen peroxide residues may interfere with COD measurements and apparent COD can be higher than the calculated theoretical oxygen demand (ThOD). Additionally PAA or hydrogen peroxide residues interfere with the BOD test resulting in BOD values that are too low. Residual PAA and ORP were found to correlate with remaining amounts of bacteria.
Environmental Science & Technology, 2015
Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown. In this study, the reactivity of PAA with halide ions (chloride and bromide) to form secondary oxidants (HOCl, HOBr) was investigated. For the PAA−chloride and PAA− bromide reactions, second-order rate constants of (1.47 ± 0.58) × 10 −5 and 0.24 ± 0.02 M −1 s −1 were determined for the formation of HOCl or HOBr, respectively. Hydrogen peroxide (H 2 O 2), which is always present in PAA solutions, reduced HOCl or HOBr to chloride or bromide, respectively. As a consequence, in PAA-treated solutions with [H 2 O 2 ] > [PAA], the HOBr (HOCl) steady-state concentrations were low with a limited formation of brominated (chlorinated) disinfection byproducts (DBPs). HOI (formed from the PAA−iodide reaction) affected this process because it can react with H 2 O 2 back to iodide. H 2 O 2 is thus consumed in a catalytic cycle and leads to less efficient HOBr scavenging at even low iodide concentrations (<1 μM). In PAA-treated solutions with [H 2 O 2 ] < [PAA] and high bromide levels, mostly brominated DBPs are formed. In synthetic water, bromate was formed from the oxidation of bromide. In natural brackish waters, bromoform (CHBr 3), bromoacetic acid (MBAA), dibromoacetic acid (DBAA), and tribromoacetic acid (TBAA) formed at up to 260, 106, 230, and 89 μg/L, respectively for doses of 2 mM (ca. 150 mg/L) PAA and [H 2 O 2 ] < [PAA]. The same brackish waters, treated with PAA with [H 2 O 2 ] ≫ [PAA], similar to conditions found in commercial PAA solutions, resulted in no trihalomethanes and only low haloacetic acid concentrations.
Chemical Engineering Journal, 2018
The aim of this study was to evaluate the influence of the physical-chemical characteristics of wastewater on PAA decay, in multi-component solutions of inorganic and organic compounds (11 compounds in total) representative of secondary effluents of wastewater treatment plants, disinfected at various PAA concentrations (2-5 mg/L). Batch experiments were defined using the statistical method of the Design of Experiments (DoE) in order to evaluate the effect of each compound and their interaction on PAA decay. Results showed that the organics consumed immediately a considerable amount of PAA, independently from the initial PAA concentration , and consumption dropped rapidly to almost nil after 5 min, whereas PAA consumption due to the inorganics was slow, dependent on the initial PAA concentration and persisted until the end of the experiments (60 min). In detail, inorganics (such as reduced iron and orthophosphate) have shown to be the main drivers of the exponential decay: iron, particularly, has proved to directly consume PAA due to its catalysing capacity, whereas orthophosphate has shown to mainly interact with iron, acting as a chelating compound towards iron and consequently reducing the iron effect in consuming PAA. As for organics, proteins such as, casein and peptone, have been highlighted as the main cause of the initial PAA demand, probably due to the homolytic fission of PAA to generate peroxyl and hydroxyl radicals, which are known to have a high reactivity towards proteins. Finally, a model for predicting the residual PAA concentration was obtained and validated; uncertainty analysis was also performed by a series of Monte Carlo simulations to propagate input uncertainties to the model output.
Disinfecting behaviour of peracetic acid for municipal wastewater reuse
Desalination, 2004
Following an increased interest in the last decade to employing peracetic acid (PAA) as an alternative disinfectant to chlorination, a study was started to investigate the technical, economic and chemical suitability of PAA for disinfecting municipal wastewater to be reused in agriculture. Laboratory and pilot-scale (10 m 3 /h) experiments of disinfecting secondary settled effluent from the municipal wastewater treatment plant of Taranto (S. Italy) were made where, under the experimental conditions investigated, the disinfection process was addressed by modelling PAA consumption and microbial inactivation by zero-order kinetics.
Pilot-plant comparative study of peracetic acid and sodium hypochlorite wastewater disinfection
Water research, 2003
Peracetic acid (PAA) use in wastewater disinfection was assessed by examining its performances in a pilot plant fed by the effluent from a conventional activated-sludge treatment plant. The influence of PAA initial concentrations (0.5-4.0 mg/l) and contact times (8-38 min) on the presence of seven microorganisms (total coliforms, fecal coliforms, fecal streptococci, Escherichia coli, Pseudomonas sp., Salmonella sp., and bacteriophages anti-E. coli) and on residual biocide and halogenated organic compound (AOXs) concentrations were evaluated. The data so obtained were compared to the corresponding results acquired using sodium hypochlorite (HYP) in the same experimental conditions. The biocide effect of PAA against total and fecal coliforms, E. coli, Pseudomonas sp. and Salmonella sp. was similar to that shown by HYP. The former disinfectant was, however, less efficient than the latter in the reduction of fecal streptococci and bacteriophages anti-E. coli. In both cases the biocide q...
Evaluation of the efficiency of peracetic acid in the disinfection of sewage effluents
Journal of Applied Microbiology, 2001
Aims: Evaluation of the ef®ciency of peracetic acid in the disinfection of wastewater in a large treatment plant. Methods and Results: Over a period of 18 months 30 sample collections were made, each consisting of three samples taken from: raw incoming sewage, secondary ef¯uent (after 10±12 h) and secondary ef¯uent disinfected with 1á5±2 mg l ±1 of peracetic acid (contact time: 20 min). Total coliforms and Escherichia coli declined from 10 7 MPN 100 ml ±1 in the raw sewage to 10 2 in the disinfected ef¯uent and the enterococci fell from 10 6 MPN 100 ml ±1 to 702 MPN 100 ml ±1 . The reduction of bacteria increased with the rise in temperature and decreased with the rise in BOD 5 . Conclusions: Disinfection with peracetic acid reduced levels of faecal contamination by 97%, thus attaining the limit recommended by current Italian law (Escherichia coli £ 5000 MPN 100 ml ±1 ) for discharge into surface waters. Signi®cance and Impact of the Study: The process of disinfection with peracetic acid is easier to manage than other more common methods and the tests performed con®rm that from the bacteriological point of view good results can be obtained for urban ef¯uents.
Peracetic acid (PAA) disinfection of primary, secondary and tertiary treated municipal wastewaters
Water Research, 2005
The efficiency of peracetic acid (PAA) disinfection against enteric bacteria and viruses in municipal wastewaters was studied in pilot-scale. Disinfection pilot-plant was fed with the primary or secondary effluent of Kuopio municipal wastewater treatment plant or tertiary effluent from the pilot-scale dissolved air flotation (DAF) unit. Disinfectant doses ranged from 2 to 7 mg/l PAA in the secondary and tertiary effluents, and from 5 to 15 mg/l PAA in the primary effluents. Disinfection contact times were 4-27 min. Disinfection of secondary and tertiary effluents with 2-7 mg/l PAA and 27 min contact time achieved around 3 log reductions of total coliforms (TC) and enterococci (EC). PAA disinfection also significantly improved the hygienic quality of the primary effluents: 10-15 mg/l PAA achieved 3-4 log reductions of TC and EC, 5 mg/l PAA resulting in below 2 log reductions. F-RNA coliphages were more resistant against the PAA disinfection and around 1 log reductions of these enteric viruses were typically achieved in the disinfection treatments of the primary, secondary and tertiary effluents. Most of the microbial reductions occurred during the first 4-18 min of contact time, depending on the PAA dose and microorganism. The PAA disinfection efficiency remained relatively constant in the secondary and tertiary effluents, despite of small changes of wastewater quality (COD, SS, turbidity, 253.7 nm transmittance) or temperature. The disinfection efficiency clearly decreased in the primary effluents with substantially higher microbial, organic matter and suspended solids concentrations. The results demonstrated that PAA could be a good alternative disinfection method for elimination of enteric microbes from different wastewaters. r
Disinfection by-products formation during wastewater disinfection with peracetic acid
Desalination, 2007
Peracetic acid (PAA) is gaining increased acceptance among chlorine-alternative chemical disinfectants claiming that only harmless disinfection by-products (DBPs) have been identified so far, most of them arising from its spontaneous decomposition. A pilot study has been undertaken, using a 10 m 3 /h pilot plant fed by municipal secondary settled effluent, in order to assess possible formation of unhealthy DBPs following its use, namely aldehydes and halogenated phenols. Negligible amount of both DBP classes was found in the experimental conditions investigated. Additionally, halogenating phenol reaction products and aldehydes formation were evaluated by carrying out a laboratory set of model reactions permitting to draw some light on mechanism of potential formation of aldehydes and brominated phenols.
Hydrogen Peroxide and Peracetic Acid Oxidizing Potential in the Treatment of Water
Revista de Chimie
Mixture based on peracetic acid and hydrogen peroxide is a more powerful oxidant than chlorine and chlorine dioxide. The reactivity of this oxidizing mixture with the polluting substances in the water: ammonium compounds, nitrites, iron, manganese, organic proteins is evaluated in this study. The results obtained after tasting this mixture, using various natural groundwater matrices shows an oxidation efficiency of over 90% of ammonium and nitrite content, between 40-70% of iron and 25-50% for manganese forms. The advantage of this oxidation mixture compared to thechlorine substances is that they do not form threehalomethane byproducts that have carcinogenic effect.
Talanta, 2018
The recent growing interest in peracetic acid (PAA) as disinfectant for wastewater treatment demands reliable and readily-available methods for its measurement. In detail, the monitoring of PAA in wastewater treatment plants requires a simple, accurate, rapid and inexpensive measurement procedure. In the present work, a method for analyzing low concentrations of PAA, adapted from the US EPA colorimetric method for total chlorine, is assessed. This method employs N,N-diethyl-pphenylelnediamine (DPD) in the presence of an excess of iodide in a phosphate buffer system. Pink colored species are produced proportionally to the concentration of PAA in the sample. Considering that PAA is available commercially as an equilibrium solution of PAA and hydrogen per-oxide (H 2 O 2), a measurement method for H 2 O 2 is also investigated. This method, as the one for the determination of PAA, is also based on the oxidation of iodide to iodine, with the difference that ammonium molybdate Mo(VI) is added to catalyze the oxidation reaction between H 2 O 2 and iodide, quantifying the total peroxides (PAA+ H 2 O 2). The two methods are suitable for concentration ranges from about 0.1-1.65 mg L −1 and from about 0.3-3.3 mg L −1 , respectively for PAA and H 2 O 2. Moreover, the work elucidates some relevant aspects related to the operational conditions, kinetics and the possible interference of H 2 O 2 on PAA measurement.