Comparison of organic peracids in wastewater treatment: Disinfection, oxidation and corrosion

Water Research 85 (2015) 275e285

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Comparison of organic peracids in wastewater treatment: Disinfection, oxidation and corrosion €mo € c, Ulla Lassi a, d Tero Luukkonen a, e, *, Tom Heyninck b, Jaakko Ra a

University of Oulu, Research Unit of Sustainable Chemistry, P.O. Box 3000, FI-90014, Finland Artesis Plantijn University College, Wetenschap en Techniek, Kronenburgstraat 47, BE-2000, Antwerpen, Belgium c University of Oulu, Thule Institute, FI-90014, Finland d University of Jyvaskyla, Kokkola University Consortium Chydenius, Unit of Applied Chemistry, Talonpojankatu 2B, FI-67100 Kokkola, Finland e Kajaani University of Applied Sciences, Kuntokatu 5, FI-87101, Kajaani, Finland b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 23 June 2015 Received in revised form 13 August 2015 Accepted 21 August 2015 Available online 24 August 2015

The use of organic peracids in wastewater treatment is attracting increasing interest. The common beneficial features of peracids are effective anti-microbial properties, lack of harmful disinfection byproducts and high oxidation power. In this study performic (PFA), peracetic (PAA) and perpropionic acids (PPA) were synthesized and compared in laboratory batch experiments for the inactivation of Escherichia coli and enterococci in tertiary wastewater, oxidation of bisphenol-A and for corrosive properties. Disinfection tests revealed PFA to be a more potent disinfectant than PAA or PPA. 1.5 mg L
1 dose and 2 min of contact time already resulted in 3.0 log E. coli and 1.2 log enterococci reduction. Operational costs of disinfection were estimated to be 0.0114, 0.0261 and 0.0207 V/m3 for PFA, PAA and PPA, respectively. Disinfection followed the first order kinetics (Hom model or S-model) with all studied peracids. However, in the bisphenol-A oxidation experiments involving Fenton-like conditions (pH ¼ 3.5, Fe2þ or Cu2þ ¼ 0.4 mM) peracids brought no additional improvement to traditionally used and lower cost hydrogen peroxide. Corrosion measurements showed peracids to cause only a negligible corrosion rate (<6 mm year
1) on stainless steel 316L while corrosion rates on the carbon steel sample were significantly higher (<500 mm year
1). © 2015 Elsevier Ltd. All rights reserved.

Keywords: Performic acid Peracetic acid Perpropionic acid Wastewater disinfection Bisphenol-A oxidation Corrosion

1. Introduction Organic peracids are peroxide compounds with an organic side chain and their structure can be generally presented with ReCOOOH. They are typically available as an equilibrium solution containing peracid, hydrogen peroxide, corresponding carboxylic acid and water (Reaction (1)). Additionally small amounts of catalysts or stabilizers can be present. ReCOOOH (aq) þ H2O (l) 4 ReCOOH (aq) þ H2O2 (aq)

(1)

Industrially the most relevant organic peracids are performic and peracetic acids (Jones, 1999). In recent years the use of organic peracids in wastewater treatment applications such as disinfection

* Corresponding author. University of Oulu, Research Unit of Sustainable Chemistry, P.O. Box 3000, FI-90014, Finland. E-mail addresses: tero.luukkonen@oulu.fi, [email protected] (T. Luukkonen). http://dx.doi.org/10.1016/j.watres.2015.08.037 0043-1354/© 2015 Elsevier Ltd. All rights reserved.

and oxidation has attracted a great deal of interest. The main drivers have been the increased awareness of disinfection byproducts resulting from traditionally used chlorine, and recalcitrant micropollutants, such as pharmaceuticals and endocrine disruptors, occurring in wastewaters. Gehr et al. (2009) published one of the first studies about the use of performic acid (PFA), CHOOOH, for wastewater disinfection. PFA is unstable and needs to be prepared on-site shortly before use (Mattila and Aksela, 2000). There are potential safety issues in the process due to the explosive nature of PFA at elevated temperatures and concentrations. PFA has been proved to be especially effective in disinfecting primary wastewater effluents (Gehr et al., 2009) and combined sewer overflows (Chhetri et al., 2015, 2014) which can be difficult to treat with other methods. Furthermore, recent pilot and full scale experiments with secondary effluents (Ragazzo et al., 2013; Karpova et al., 2013) have indicated that a dose of 1.0e1.2 mg L
1 and contact time 10 min are already sufficient to reach 2.2e4.0 log removal of fecal coliforms or Escherichia coli. The cost of PFA-based disinfection to reach 10 CFU/100 mL E. coli in

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T. Luukkonen et al. / Water Research 85 (2015) 275e285

wastewater was reported to be 0.0101 V/m3 (Ragazzo et al., 2007). Eco-toxicity and disinfection by-products formation studies with PFA are still scarce but the results of Ragazzo et al. (2013) obtained under operational conditions indicated that no appreciable changes occurred in the Vibrio fischeri light suppression test or in the amount of volatile organic compounds after the disinfection. PFA is a strong oxidizer and it has been tested for the degradation of pharmaceuticals in primary wastewater (Gagnon et al., 2008) and refractory organic compounds in landfill leachates (Hagman et al., 2008). However, both studies showed poor removal results possibly due to rapid and non-selective reactions of PFA. Peracetic acid (PAA), CH3COOOH, was first proposed for wastewater disinfection over 30 years ago (Baldry, 1983; Meyer, 1976) and has been studied extensively since (Kitis, 2004). Secondary wastewater effluents require typically a 2e7 mg L
1 dose and approximately 30 min contact time to reach 3 log reduction in total coliform number (Koivunen and Heinonen-Tanski, 2005). Biologically treated and filtered tertiary effluents can be disinfected already with a dose of 1.5e2 mg L
1 and contact time of 10e15 min to reach the EU bathing water quality for E. coli (Luukkonen et al., 2014). However, the required dose and contact time strongly depend on wastewater quality (Koivunen and Heinonen-Tanski, 2005). Unlike PFA, PAA is available as a stabilized equilibrium solution thus making it technically easier to apply. The main beneficial features of PAA, which are largely similar to PFA, are the lack of harmful disinfection by-products under typically applied conditions (Dell'Erba et al., 2007; Liberti and Notarnicola, 1999; Nurizzo et al., 2005; Crebelli et al., 2005) and no significant re-growth of bacteria occurring after disinfection (Antonelli et al., 2006). The activity of PAA against microbes is proposed to be based on the formation of highly oxidizing radicals which is probably the mechanism of other peracids as well. Furthermore, it was recently shown that hydrogen peroxide has an important synergistic effect in the PAA disinfection process (Flores et al., 2014). The cost of PAAbased disinfection (4e14 mg L
1, 30 min contact time, tertiary wastewater effluent) has been estimated to be 0.048e0.098 V/m3 depending on the required microbial quality (Nurizzo et al., 2001). The high oxidation potential of PAA, 1.959 V vs normal hydrogen electrode (Awad et al., 2004), has been applied for the degradation of phenol (Rokhina et al., 2010), organic dye (Rothbart et al., 2012) and pharmaceuticals in biologically treated wastewater (Hey et al., 2012) as well as oxidation of activated sludge as a pretreatment for anaerobic digestion (Appels et al., 2011). Literature concerning perpropionic acid (PPA), CH3CH2COOOH, is much more limited when compared to PAA or PFA. No published studies exist for wastewater treatment applications. However, the general disinfective properties of PPA are well known (Merka and k, 1968; Merka et al., 1965) and it has been successfully Dvora used, for example, in the decontamination of food-contact surfaces (Vimont et al., 2014). Oxidative properties of PPA have been tested for the degradation of organophosphorus and organosulfur pollutants in micellar solutions (Lion et al., 2002) and for the oxidation of NOx and SO2 from flue gas (Littlejohn and Chang, 1990). Although PAA has been already studied extensively and there are several studies about wastewater disinfection with PFA, the amount of comparative studies is still limited. This applies especially for disinfection kinetics. Furthermore, no studies regarding the wastewater disinfection or oxidation capacities of PPA exist. However, one of the few comparison studies by Merka et al. (1965) indicated PFA, PAA and PPA to have a similar efficiency against Bacillus subtilis spores, E. coli and Staphylococcus aureus. Another pioneering study showed that PFA is a more potent sporicidal agent k, 1968). Additionally, the virucidal efthan PPA (Merka and Dvora ficiency of PAA and PPA was found to be similar when disinfecting food-contact surfaces (Vimont et al., 2014). Yousefzadeh et al.

(2014) on the other hand concluded PFA to be less effective than free chlorine when disinfecting sterilized active sludge effluent containing E. coli. In this study PFA, PAA and PPA were compared in the disinfection of tertiary wastewater and in the oxidation of bisphenol-A (BPA) with Fenton-like reactions. BPA was selected as a model compound as it is a well-known endocrine disruptor which is widely used as a plasticizer and as a plastic monomer (Vandenberg et al., 2007). Elevated concentrations of BPA can be encountered in industrial effluents while it is present as a micropollutant in municipal wastewaters and drinking waters. Furthermore, uniform corrosion caused by peracids for two steel alloys was evaluated by electrochemical measurements in the concentrations typically used in wastewater applications since no data of this kind are available. 2. Experimental 2.1. Water samples A chemicallyebiologically treated and filtered tertiary wastewater sample from The Taskila municipal wastewater treatment plant (Oulu, Finland) was used in the disinfection and peracid decompositions experiments. Additionally, tap water was used in the peracid decomposition experiments. Metal concentrations of water samples were determined by an optical emission spectrometer (Perkin Elmer Optima 5300 DV) while conductivity and pH were measured with a Hach HQ40d meter. Chemical oxygen demand (CODCr), total nitrogen and phosphate were determined using a Hach Lange DR 2800 photometer and cuvette tests LCK314, LCK138 and LCK349, respectively. Seven day biological oxygen demand with allylthiourea addition (BOD7, atu) was determined with the OxiTop manometric respirometric method. 2.2. Preparation of peracids Peracids were prepared by mixing 10 mL of carboxylic acid with 0.94 mL of 95e97% (w/w) sulfuric acid (Baker) in a round-bottom flask placed in an ice-bath. 10 mL of 30% (w/w) hydrogen peroxide (Merck) was then slowly added. Contents of the flask were mixed with a magnetic stirrer (250 rpm) for 90 min and the flask was moved to the refrigerator. The carboxylic acids used in the synthesis were 98e100% formic acid (Merck), 99e100% acetic acid (Baker) and 99% propionic acid (Merck). The commercial peracetic acid (Desirox 12:20) sample was received from Solvay. 2.3. Concentration measurements of peracids Concentrations of prepared peracids were measured with a twostage cerimetriceiodometric titration method (Greenspan and Mackellar, 1948). Gehr et al. (2009) presented a modification involving the addition of molybdate catalyst before iodometric titration. 0.1 mL of peracid was weighed and placed in an Erlenmeyer flask containing 10 mL 5% (w/w) sulfuric acid (Baker). The Erlenmeyer flask was kept in an ice bath to maintain the temperature under 10  C. Three drops of ferroin indicator (Riedel) was added and the contents of the Erlenmeyer were titrated with 0.1 M ceric sulfate (Merck). The volume used was recorded as VT1. A color change from orange to light blue occurred at the equivalence point. Ce4þ reacts with hydrogen peroxide according to the Reaction (2). 2Ce4þ (aq) þ H2O2 (aq) / 2Ce3þ (aq) þ 2Hþ (aq) þ O2 (aq)

(2)

5 mL of 10% potassium iodide (Merck) solution, three drops of molybdate (Merck) solution and 1 mL of starch (Merck) indicator

T. Luukkonen et al. / Water Research 85 (2015) 275e285

were added. Peracid oxidizes iodide to iodine which was titrated with 0.1 M sodium thiosulfate (VWR Chemicals) according to Reaction (3). The volume used was recorded as VT2. 2S2O3

2


2


(aq) þ I2 (aq) / S4O6




(aq) þ 2I (aq)

w VT1  c1  M1  ½ ¼  100% Hydrogen peroxide %; w m 

(4)

where VT1 is the consumption of cerium sulfate (L), c1 is the concentration of cerium sulfate (0.1 M), M1 is the molar mass of hydrogen peroxide (34.01 g mol
1) and m (g) is the mass of the titrated sample.

 w V  c  M  ½ 2 2 ¼ T2  100% Peracid %; w m

(5)

where VT2 is the consumption of sodium thiosulfate (L), c2 is the concentration of sodium thiosulfate (0.1 M), M2 is the molar mass of peracid (62.02 g mol
1 for PFA, 76.05 g mol
1 for PAA and 90.08 g mol
1 for PPA) and m is the mass of the titrated sample (same values as in Equation (3)).

2.4. Decomposition kinetics of peracids The decomposition rates of peracids (initial concentration 15 mg L
1) were determined in tertiary wastewater and in tap water by taking samples at different intervals. The experiments were conducted in duplicate. Samples were analyzed with a modified cerimetriceiodometric titration method described by Cavallini et al. (2013). 500 mL of 1 M sulfuric acid in an ice bath and 20 drops of ferroin indicator were titrated with 0.02 M ceric sulfate until the color change from orange to blue occurred. 10 mL of this solution was mixed with 50 mL of the sample to be determined. Again, this solution was titrated with 0.02 M ceric sulfate and the volume used was recorded as VT3. After titration, 1 mL of 10% potassium iodide and 1 mL of starch indicator were added and the sample was then titrated with 0.01 M sodium thiosulfate. The volume used was recorded as VT4. The concentrations can be calculated with Equations (6) and (7).

 V  c M ½  3 1 Hydrogen peroxide mg L
1 ¼ T3  1000 VS

(6)

where VT3 (L) is the consumption of ceric sulfate, c3 is the concentration of ceric sulfate (0.02 M), M1 is the molar mass of hydrogen peroxide and Vs is the volume of the sample (0.050 L).

 V  c  M  ½  4 2 Peracid mg L
1 ¼ T4  1000 VS

Ct ¼ ðC0
DÞ
k0 t

(8)

Ct ¼ ðC0
DÞe
k1 t

(9)

(3)

The concentrations of hydrogen peroxide and peracid can be calculated according to Equations (4) and (5), respectively.

(7)

where VT4 (L) is the consumption of sodium thiosulfate, c4 is the concentration of sodium thiosulfate (0.01 M), M2 is the molar mass of peracid and Vs is the volume of the sample (0.050 L). Kinetics of decomposition was modeled using zero-order, firstorder and second-order models (Equations (8)e(10), respectively) with the initial peracid consumption, D (mg L
1) (Falsanisi et al., 2006). The parameters k0 (mg L
1 min
1), k1 (min
1) and k2 (mg
1 L min
1) are the kinetic constants of the models, C0 and Ct (mg L
1) are the initial concentration and concentration at time t (min).

277

Ct ¼

ðC0
DÞ 1 þ k2 ðC0
DÞt

(10)

The values of parameters were obtained with non-linear regression using The Microsoft Excel Solver-function GRGnonlinear. Additionally, the values of the coefficient of determination (R2), the residual root mean square error (RMSE) and the chisquare (Х2) test were used to evaluate the model fitting and the similarity of the calculated and experimental values. 2.5. Disinfection experiments Different concentrations (1.5, 3.0 and 5.0 mg L
1) of peracids were dosed to wastewater samples that were constantly mixed with magnetic stirrers. Experiments were performed at a water temperature of approx. 15  C. Samples at different time intervals were taken to sterile plastic bottles containing 9% (w/V) sodium thiosulfate (1 mLe1 mL sample) to quench peracids. It was ensured that possible residual hydrogen peroxide (maximum 8.3 mg L
1) after peracid quenching had no bactericidal effect by testing its disinfection efficiency alone. Samples were then stored at a temperature of approx. 5  C. The numbers of E. coli and enterococci were estimated using membrane filtration methods within six hours (SFS-EN ISO 9308-1, 2014; SFS-EN ISO 7899-2, 2000). The presence of E. coli was confirmed using cytochrome oxidase detection quick test strips (Merck Microbiology Bactident Oxidase). Disinfection experiments were conducted in duplicate. The disinfection results were modeled using ChickeWatson, Hom, and S-models. The ChickeWatson model (Chick, 1908; Watson, 1908) can be presented with Equation (11) (in integrated form).

ln

Nt ¼
LC n t N0

(11)

where Nt is the number of microbes at time t (min), N0 is the initial number of microbes, L is a constant related to the specific microorganism and the set of conditions and n (dimensionless) is the coefficient of dilution. The values of n > 1 indicate that the concentration is more important than contact time in achieving a k and Finch, 1998). certain inactivation level and vice versa (Gyüre The Hom model (Hom, 1972) (Equation (12), in integrated form) is able to describe the deviations from linearity in the survival curve.

ln

Nt ¼
kC n t m N0

(12)

where n and m (dimensionless) are empirical constants which define the curvature of the plot: when m > 1, the survival curve displays an initial shoulder and when m < 1, the survival curve displays a tailing-off effect. The S-model (Profaizer, 1998) (Equation (13)) introduces an additional empirical constant h (mg min L
1) which allows to describe the inactivation kinetics when the survival curve contains three phases: initial resistance to inactivation (shoulder), exponential inactivation and asymptotic inactivation (tailing-off).

ln

Nt kC n ¼
N0 1 þ ð h Þm Ct

(13)

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T. Luukkonen et al. / Water Research 85 (2015) 275e285

The values of model parameters were again obtained with nonlinear regression using the Microsoft Excel Solver-function GRGnonlinear. The RMSE and the chi-square test were calculated. 2.6. Oxidation experiments 60 mg L
1 BPA (Sigma Aldrich) solution was prepared in deionized water. BPA oxidation was done as batch experiments in an open glass reactor (V ¼ 500 mL) at room temperature using continuous mixing. The volume of BPA solution in the reactor was 200 mL. The concentrations of oxidizers were 25 and 50 mg L
1 for hydrogen peroxide (HP) and 20 mg L
1 for PFA, PAA and PPA. The first oxidation experiment was done without any pH adjustment or the addition of catalysts. In the Fenton-like experiments, 0.4 mM concentration of Fe2þ or Cu2þ was used as a catalyst. Solution pH was adjusted to 3.5. Samples (V ¼ 2 mL) were taken at different time intervals (0e60 min) and the oxidation reaction was quenched by the addition of 20 mL of 20% (w/v) sodium thiosulfate solution. The concentration of BPA was estimated with a Shimadzu SPD-10A high performance liquid chromatograph using a UV detector at 226 nm. 2.7. Corrosion experiments Peracid concentrations of 2 and 15 mg L
1 were used in the corrosion measurements to simulate regular disinfection and shock treatment concentration levels. Sodium sulfate (500 mg L
1) was used as a background electrolyte. A three electrode system consisting of a working electrode (steel samples), a reference electrode (saturated calomel electrode) and a counter electrode (a platinum foil) was used to determine the corrosion rate, current density and potential. The condition of the reference electrode was monitored by measuring the potential difference against the Ag/AgClelectrode regularly. The measurements were conducted at room temperature. The steel samples were polished with SiC polishing paper grades 120, 240, 600 and 1200 and rinsed with acetone before measurements. Steel samples were a stainless steel alloy (316L) with the following composition (w/w %): 0.02% C, 17.2% Cr, 10.2% Ni and 2.10% Mo and a carbon steel alloy (w/w %): 0.17% C, 1.50% Mn, 0.46% Si 0.03% Cr and 0.03% Ni. Steel samples were allowed to equilibrate with peracid solutions at open circuit potential for 2 h before starting the measurements. Tafel plots were obtained by polarizing to ±250 mV with respect to the free corrosion potential (Ec) using a scan rate of 0.5 mV s
1. The measurements were done using a Versatat 3 potentiostat (Princeton Applied Research) and a flat cell set-up. Pictures of the corroded surfaces were taken with a laser microscope (Keyence VK-X200 series). Uniform corrosion rate (CR, mm year
1) was calculated in terms of penetration rate using Equation (14) where K1 (3.27  10
3 (mm g mA
1 cm
1 year
1) is a constant, icor (mA cm
2) is the corrosion current density, r (g cm
3) is the density of the sample and EW is the equivalent weight (dimensionless) calculated according to the standard (ASTM G102-89, 2010). The corrosion measurements were done at least in triplicate.

CR ¼ K1

icor EW r

(14)

3. Results and discussion

PAA and PPA the equilibrium was reached only after approx. 2 and 5 days, respectively. The equilibrium concentrations of PFA, PAA and PPA were approx. 9, 16 and 17% (w/w), respectively. The densities of PFA, PAA and PPA were approx. 1.21, 1.17 and 1.11 g cm
3, respectively. The long term stability results of peracids stored at 5  C are shown in Fig. 1b. Due to the instability of PFA, approx. 50% of the chemical decomposed in 20 days. Freshly prepared PFA has been reported to be stable in an ice bath for 5 h (Karpova et al., 2013). On the other hand, PAA and PPA remained relatively stable for the whole monitoring time (77 days). These results are consistent with the observation that the stability of aliphatic peracids increases with increased chain length (Swern, 1949). Commercial PAA solutions are stabilized for example with alkali metal polyphosphates or quinoline derivatives (Gunter et al., 1969). Decomposition data of peracids in wastewater and tap water are shown in Fig. 2 and the physico-chemical quality parameters of water samples in Table 1. As there are only trace amounts of suitable metal catalysts but no appreciable amount of consuming organic matter, the decomposition of peracids occurs slower in tap water than in wastewater. Furthermore, the decomposition results were modeled using 0, 1st and 2nd order kinetic models taking into account the possible initial peracid consumption (D). The parameters obtained with non-linear regression are shown in Table 2. PFA decomposition in tap water can be described best with 1st order kinetics (R2 ¼ 0.968) while PAA, commercial PAA and PPA decomposition follow 0 order kinetics: R2 ¼ 0.973, 0.907 and 0.941, respectively. Furthermore, RMSE and Х2 are smaller than with other models which indicate similarity between calculated and experimental values. However, the decomposition kinetics of PAA, commercial PAA and PPA can be described almost equally well the 1st order model as well. In the case of PFA and PAA, the initial instantaneous consumption (D) is 0 while for commercial PAA and PPA there is initial consumption (D ¼ 0.806 and 1.82 mg L
1, respectively). Kinetic constants of the 1st order model in tap water follow the order PFA > PPA > PAA > commercial PAA. The results indicate that the stabilizers present in the commercial PAA slow the decomposition compared to unstabilized synthesized PAA. PFA decomposition data fits best for 1st order kinetics also in wastewater (R2 ¼ 0.955) and there is no initial consumption which is somewhat unexpected due to the reactivity of PFA. Decomposition kinetics data for PFA in a wastewater matrix is very scarce in the literature. However, Chhetri et al. (2015) reported concentration profiles for PFA in a combined sewer overflow effluent which closely resembles those obtained in our study, i.e. no initial consumption. Decay of PAA concentration in wastewater follows 0 order kinetics (R2 ¼ 0.993) with D ¼ 0.925 mg L
1 although again 1st order kinetics seem to appropriately describe the decomposition (R2 ¼ 0.992). Both 0 order (Santoro et al., 2007) and 1st order (Falsanisi et al., 2006; Rossi et al., 2007) kinetics for PAA decay in wastewater have been reported with the 1st order kinetic constants for PAA decay being in the range of 0.0028e0.0396 min
1. These are in agreement with our results: 0.004 and 0.005 min
1 for PAA and commercial PAA, respectively. PAA decomposition kinetics depends strongly on factors such as the presence of an organic material (Pedersen et al., 2013) and temperature (Kunigk et al., 2001). PPA decomposition fits well to 1st and 2nd order models: R2 ¼ 0.979 and 0.977, respectively. To the authors' best knowledge, no literature data for aqueous PPA decomposition kinetics exists. 1st order kinetic constants in wastewater follow the order: PFA > PAA > commercial PAA > PPA.

3.1. Formation and decomposition of peracids 3.2. Disinfection Peracid concentrations during the synthesis are shown in Fig. 1a. PFA concentration reached equilibrium at approx. 75 min while for

Disinfection experiments were initially performed using the

T. Luukkonen et al. / Water Research 85 (2015) 275e285

279

▫

Fig. 1. Change of PFA (B), PAA ( ) and PPA (D) concentrations during a) synthesis and b) storage at T z 5  C.

concentrations 1.5, 3.0 and 5.0 mg L
1 of PFA, PAA or PPA to estimate the required dosing level (data not shown). The aim was to reach the EU bathing water directive microbial limits (Directive 2006/7/EC, 2006) (Table 3) for which the 1.5 mg L
1 PFA and 3.0 mg L
1 PAA or PPA proved to be sufficient. However, the 1.5 mg L
1 dose was selected for the kinetics modeling. E. coli inactivation results obtained with 1.5 mg L
1 dose of PFA, PAA or PPA are shown in Fig. 3. The initial E. coli number was on average 29,200 CFU/100 mL. The action of PFA is almost instantaneous and a 2.9 log reduction is already achieved after 1 min contact time (E. coli 33 CFU/100 mL).

After 60 min contact time the reduction was 3.5 log and the number of E. coli had decreased to average 10 CFU/100 mL. The result already at 1 min is within the “excellent quality” described by the EU bathing water requirements. The E. coli inactivation obtained with PAA (1.5 mg L
1) is clearly smaller compared to PFA: the reduction at 60 min is only 1.6 log (E. coli 690 CFU/100 mL). Nevertheless, the results obtained with PAA are still within “good quality” for inland waters but not within the range defined for coastal or transitional waters. However, already a modest dilution occurring as wastewater is discharged would reduce the number of E. coli sufficiently to reach the quality requirements. For PPA the

Fig. 2. Decomposition of a) performic acid, b) peracetic acid, c) commercial peracetic acid and d) perpropionic acid in tap water (grey, open points) and wastewater (black, solid points). The best fitting kinetic models are presented with solid lines while dashed lines are a 95% confidence interval.

280

T. Luukkonen et al. / Water Research 85 (2015) 275e285

Table 1 Physico-chemical characteristics of tap water and wastewater samples.

pH Conductivity [mS cm
1] BOD7, atu [mg L
1] CODCr [mg L
1] Phosphate [mg L
1] Turbidity [NTU] Total solids [mg L
1] Absorbance @ 254 nm [cm
1] Al [mg L
1] Ca [mg L
1] Cu [mg L
1] Fe [mg L
1] Mg [mg L
1] Mn [mg L
1] Zn [mg L
1]

Tap water

Wastewater

7.46 178 e e e 0.280 e 0.0180 <0.10 25.0 <0.10 <0.10 1.30 <0.10 <0.10

7.41 879 2.35 53.4 0.188 5.49 391 0.398 0.100 36.3 <0.10 0.900 6.53 0.270 <0.10

Table 3 The EU bathing water directive (Directive 2006/7/EC, 2006) microbial limits for inland and coastal or transitional waters. Excellent quality Good quality Sufficient Inland waters Intestinal enterococci [CFU/100 mL] 200a 400a Escherichia coli [CFU/100 mL] 500a 1000a Coastal and transitional waters Intestinal enterococci [CFU/100 mL] 100a 200a Escherichia coli [CFU/100 mL] 250a 500a a b

330b 900b 185b 500b

Based on a 95-percentile evaluation. Based on a 90-percentile evaluation.

applied models: ChickeWatson, Hom, and S-model (Table 4). As there are deviations from linearity in Figs. 3 and 4 it is obvious that the ChickeWatson model is not appropriate for describing the kinetics, and thus data is not shown. The obtained R2 values with the ChickeWatson model were generally poor (<0.3) with the exception of inactivation of enterococci with PAA or PPA for which R2 values were 0.925 and 0.781, respectively. E. coli inactivation with PFA can be described equally well using the Hom model (R2 ¼ 0.786) or the S-model (R2 ¼ 0.784). Evaluation of PFA disinfection kinetics in wastewater is very scarce in the literature. One of the few studies is by Yousefzadeh et al. (2014) who used the Hom model to describe E. coli inactivation. They reported the values of n, k and m to be 0.48, 0.54 and 0.87 in sterilized activated sludge effluent and 4.25, 0.35 and 0.35 in tap water. If the Hom model parameters n is greater than m (as in this study), the disinfectant dose is a more important factor than contact time in the disinfection process. Enterococci inactivation by PFA is best described with the S-model (R2 ¼ 0.976). The inactivation of E. coli by PAA is best described with the Smodels (R2 ¼ 0.945). The parameters obtained are in good agreement with earlier studies that have concluded E. coli inactivation by PAA to best fit the S-model (Azzellino et al., 2011; Rossi et al., 2007). Furthermore, enterococci inactivation data also fits best to the Smodel (R2 ¼ 0.981) and the curve (Fig. 4) has three distinctive phases: shoulder, exponential inactivation and tailing-off. The shoulder phase could be caused by more preferred inactivation of E. coli over enterococci.

inactivation occurs slightly faster than with PAA and the final reduction at 60 min is 2.5log (E. coli 99 CFU/100 mL). This result is again within the “excellent quality” for bathing waters. The results indicate that the disinfection efficiency against E. coli of these chemicals is PFA > PPA > PAA. The inactivation results of enterococci are shown in Fig. 4. The average initial enterococci number was 1840 CFU/100 mL. The enterococci inactivation by PFA saturates to 2.8 log after 10 min contact time and the remaining number of enterococci is approx. 3 CFU/100 mL. The tailing-off effect is due to the fact that practically all enterococci have been inactivated. The results of PAA and PPA resemble each other and final reductions are 1.0 and 0.9 log for PAA and PPA, respectively. The corresponding final enterococci numbers for PAA and PPA are 167 CFU/100 mL and 172 CFU/100 mL, respectively. The obtained results are within “excellent quality” for inland and “good quality” for coastal and transitional waters, respectively. The results indicate that the disinfection efficiency against enterococci is PFA > PAA z PPA. These results are consistent with previous comparison studies between PFA and PAA for wastewater disinfection (Chhetri et al., 2014; Ragazzo et al., 2013) which indicate PFA to be more effective. Disinfection kinetics was evaluated using the most commonly

Table 2 Kinetic model parameters for peracid decomposition in tap water and wastewater. Tap water

Wastewater

0 order

PFA PAA Commercial PAA PPA

0 order

k [mg L
1 min
1]

D [mg L
1]

R2

RMSE

Х2

k [mg L
1 min
1]

D [mg L
1]

R2

RMSE

Х2

5.90E-02 1.59E-02 9.55E-03 2.26E-02

1.47 ea 0.810 1.89

0.937 0.972 0.907 0.941

1.04 0.194 0.0835 0.244

3.92 7.69E-03 1.72E-03 2.38E-02

5.99E-02 4.19E-02 3.57E-02 3.19E-02

2.48 0.925 1.42 2.55

0.848 0.995 0.958 0.955

2.15 0.501 0.636 0.534


0.0503 0.152 0.233 0.231

D [mg L
1]

R2

RMSE

Х2

e ea 0.785 1.90

0.955 0.994 0.951 0.979

1.17 0.552 0.685 0.362

1.92 0.224 0.331 0.102

1st Order
1

k [min PFA PAA Commercial PAA PPA

]

1st Order
1

D [mg L

]

a

R

2

RMSE

Х

2

a

a

e ea 0.806 1.82

0.968 0.970 0.906 0.929

0.733 0.204 0.0837 0.268

0.449 8.44E-03 1.73E-03 2.89E-02

k [L mg
1 min
1]

D [mg L
1]

R2

RMSE

Х2

k [L mg
1 min
1]

D [mg L
1]

R2

RMSE

Х2

8.43E-04 7.37E-05 2.26E-05 9.67E-05

ea ea 0.818 1.75

0.852 0.962 0.904 0.917

1.59 0.228 0.085 0.291

2.25 1.07E-02 1.77E-03 3.43E-02

1.31E-03 5.62E-04 4.40E-04 3.78E-04

ea ea 0.0716 1.26

0.831 0.975 0.930 0.977

2.27 1.11 0.819 0.381

6.47 0.919 0.505 0.0991

7.46E-03 9.44E-04 2.95E-04 1.11E-03 2nd Order

PFA PAA Commercial PAA PPA

k [min
1] 1.16E-02 4.88E-03 3.82E-03 3.38E-03 2nd Order

Optimum solution was obtained by assuming the parameter as zero.

T. Luukkonen et al. / Water Research 85 (2015) 275e285

281

Fig. 3. E. coli inactivation results obtained using 1.5 mg L
1 dose of a) performic, b) peracetic and c) perpropionic acid. The solid lines are calculated according to the S-model and dotted lines represent the 95% confidence limit. The average initial E. coli number was 29,200 CFU/100 mL.

Fig. 4. Enterococci inactivation results obtained using 1.5 mg L
1 dose of a) performic, b) peracetic and c) perpropionic acid. The solid lines are calculated according to the S-model and dotted lines represent the 95% confidence limit. The average initial enterococci number was 1840 CFU/100 mL.

E. coli and enterococci inactivation results obtained with PPA fit best for the S-model: R2 is 0.969 and 0.930, respectively. To the authors' best knowledge, this is the first time PPA disinfection kinetics in wastewater has been reported. 3.3. Oxidation The 60 mg L
1 concentration of BPA was selected to simulate difficult industrial wastewater matrixes. The oxidation of BPA with

hydrogen peroxide (HP) or peracids in the absence of a catalyst using a concentration of 25 or 50 mg L
1 for HP and 20 mg L
1 for peracids resulted in no degradation during 60 min contact time. This result was due to the fact that the oxidation by peroxides generally requires activation by, for example, metal cations (Jones, 1999). Therefore, Fe2þ or Cu2þ was selected as a catalyst in the further experiments and pH was lowered to 3.5 to induce Fenton or Fenton-like reactions. The results of oxidation experiments are shown in Fig. 5. The effect of catalyst (Cu2þ or Fe2þ), oxidizer

Table 4 Disinfection kinetics parameters obtained using 1.5 mg L
1 dose. E. coli

Hom

S-model

n k m RMSE Х2 R2 n k m h RMSE Х2 R2

Enterococci

PFA

PAA

PPA

PFA

PAA

PPA

1.89 3.15 0.0417 0.287
0.0523 0.786 0.0505 15.1 0.0805 30.3 0.322
0.0526 0.784

0.0600 0.714 0.417 0.449
0.577 0.920 0.0599 5.08 0.829 25.4 0.418
0.347 0.945

0.0600 1.04 0.418 0.516
1.58 0.937 0.0299 6.51 0.912 17.1 0.403
0.348 0.969

1.21E-05 2.47 0.258 1.02
3.20 0.820 0.0942 6.16 1.44 4.16 0.417
0.216 0.976

0.100 0.0853 0.819 0.405
3.08 0.905 0.101 2.39 5.56 41.7 0.210
0.500 0.981

0.0100 0.145 0.674 0.385
0.967 0.856 0.100 2.20 2.14 26.3 0.299
0.294 0.930

282

T. Luukkonen et al. / Water Research 85 (2015) 275e285

▫

Fig. 5. Bisphenol-A oxidation with PFA (B), PAA ( ), commercial PAA (◊), PPA (D) and HP (): a) effect of contact time (dose 20 mg L
1 for peracids) using Cu2þ as a catalyst, b) effect of contact time (dose 25 mg L
1 for HP and 20 mg L
1 for peracids) using Fe2þ as a catalyst and c) effect of oxidizer dose (contact time 10 min, Fe2þ as catalyst).

concentration and contact time were studied. The results obtained with Cu2þ or Fe2þ catalyst (0.4 mM) are very similar (Fig. 5a and b). The only difference is that PPA reaches equilibrium faster with Cu2þ. Most of the oxidation occurs already within 3 min contact time. The results indicate that an increase in the concentration of oxidizers results in a higher degree of BPA decomposition (Fig. 5c). However, the curves are not linear. This could be explained by the observation that the excess oxidizer in a Fenton-like process can act as a radical scavenger (Mijangos et al., 2006). The order of oxidation efficiency is commercial

PAA > HP > PAA z PPA > PFA. However, all peracid solutions also contain hydrogen peroxide in addition to the peracid itself. In fact, the amount of hydrogen peroxide present in the peracid solutions is the following: commercial PAA > HP > PFA > PAA z PPA. It was not possible to distinguish between the oxidative effect caused by the hydrogen peroxide and peracid. Although commercial PAA caused slightly higher BPA oxidation than HP, the higher price of PAA will reduce the practical applicability of the results. However, it has been noted that peracid-based oxidation is not prone to the catalase enzyme-induced decomposition which is the case with HP-

▫

Fig. 6. a) Stainless steel 316L and b) carbon steel uniform corrosion rates (penetration rates) as a function of PFA (B), PAA ( ), commercial PAA (◊) or PPA (D) concentration. The error bars represent standard error. The solution conductivities were between 690 and 1000 mS cm
1.

T. Luukkonen et al. / Water Research 85 (2015) 275e285

283

Table 5 Corrosion potential (Ec), corrosion current densities (Icor) and corrosion rates (CR) with peracids obtained for stainless steel 316L and carbon steel. Stainless steel 316L

Carbon steel

Peracid

C [mg L
1]

pH

Ec [mV]

Icor [nA cm
2]

CR [mm year
1]

Ec [mV]

Icor [mA cm
2]

CR [mm year
1]

e PFA PFA PAA PAA C-PAAa C-PAAa PPA PPA

e 2 15 2 15 2 15 2 15

8.17 4.79 3.37 6.42 4.49 6.44 5.35 6.56 4.38


107 57.2 97.2 133 241 103 199 55.1 245


27.8
136
521
50.4
76.1
42.0
186
93.5
114

0.266 1.41 5.41 0.523 0.790 0.436 1.93 0.971 1.18


627
383
676
486
664
567
732
677
721


28.1
30.8
60.4
27.1
40.1
32.4
57.3
35.4
58.2

221 242 474 213 316 254 468 279 458

a

C-PAA ¼ commercial PAA.

based oxidation (Rothbart et al., 2012). PFA, non-commercial PAA and PPA proved to be significantly less effective than HP. The results indicate that the application of peracids in Fenton conditions brings no additional benefits compared to HP. 3.4. Corrosion Uniform corrosion rates (penetration rates) of stainless steel (316L) and carbon steel as a function of applied peracid concentration are shown in Fig. 6. Results with the stainless steel (316L) indicate very low uniform corrosion rates for all peracids. However, PFA is clearly more corrosive than commercial PAA, PAA or PPA. Qu et al. (2008) studied the corrosion rates of cold rolled steel exposed to PAA in concentrations between 0.005 and 0.485 mol L
1 (380e36884 mg L
1) and temperatures 0e30  C. They observed maximum corrosion rates at temperature 20  C: 0.18e7.52 mm year
1. However, these conditions are not likely to be used in wastewater treatment but rather in bleaching applications. Furthermore, the increase in peracid concentration displaced the corrosion potential in the positive direction (Table 5) similarly as in the study by Qu et al. (2008).

Carbon steel corrosion current densities and subsequently corrosion rates are significantly higher than with stainless steel 316L. On the other hand, corrosion potentials are clearly lower. PAA gives the lowest corrosion rate value while other peracids are very similar. The visual examination and laser microscopy profile determination of the carbon steel surfaces after measurement (Fig. 7) revealed that all peracids and background electrolyte resulted similar kinds of damage. The dots on the surface are deposits with a height of approx. 10 mm. However, the increase in the peracid concentration accelerates the corrosion process which can be seen as increased corrosion rate. 3.5. Cost evaluation of disinfection The comparison of estimated chemical prices with operational and investment costs of peracid-based disinfection are shown in Table 6. Operational costs include chemical consumption in tertiary effluent to reach EU bathing water quality requirements (Directive 2006/7/EC, 2006). The calculations indicate that the operational cost of peracid-based disinfection would be in the order:

Fig. 7. Carbon steel sample surfaces after exposure to a) background electrolyte (500 mg L
1 Na2SO4) or b) 15 mg L
1 PFA, c) PAA, d) commercial PAA and e) PPA.

284

T. Luukkonen et al. / Water Research 85 (2015) 275e285

Table 6 Estimated chemical prices with operational and investment costs of peracid-acid based disinfection. Peracid

Chemical price [V/t]

Operational costs [V/m3]

Investment costs

PFA PAA PPA

830a 1100e1200b 1300c

0.0114 (1.5 mg L
1 dose) 0.0261 (3.0 mg L
1 dose) 0.0207 (3.0 mg L
1 dose)

50,000d 15,000e4,40,000e 15,000e4,40,000e

a

1:1 w/w formic acid (980 V/t) and hydrogen peroxide (670 V/t). Stabilized peracetic acid. c 1:1 w/w propionic acid (1900 V/t) and hydrogen peroxide (670 V/t). d Up to 2,00,000 m3/d capacity wastewater treatment plant. e For 3000e2,00,000 m3/d capacity wastewater treatment plants, converted to 2014 price level (Collivignarelli et al., 2000). b

PAA > PPA > PFA. The investment costs are different as PFA is prepared on-site and PAA and PPA can be supplied as a ready-touse solution. The PFA production system (Ragazzo et al., 2013) would be more economical at larger capacity plants while for small plants PAA and PPA investment costs (storage and dosing equipment) would be smaller. 4. Conclusions  PFA was more unstable than PAA or PPA in terms of shelf life and decomposition of residual concentration.  Disinfection efficiency of the chemicals against E. coli was PFA > PPA > PAA and against enterococci PFA > PPA z PPA. The kinetics of disinfection was best described using the S-model which is a first-order kinetics model. The results indicate PFA to be the most potent disinfectant.  The operational costs (chemicals) were estimated to be in the order: PAA (0.0261 V/m3) > PPA (0.0207 V/m3) > PFA (0.0114 V/ m3). For small capacity wastewater plants the investment cost of PAA or PPA could be smaller than for PFA but as the plant size increases, PFA becomes more economical.  Oxidation of bisphenol-A using Fenton conditions (pH ¼ 3.5, Fe2þ or Cu2þ ¼ 0.4 mmol L
1) was most efficient using commercial PAA although the difference compared to hydrogen peroxide was small. PFA, PAA and PPA were poor oxidizers. Based on the results, the use of peracids instead of traditionally used hydrogen peroxide in Fenton-like oxidation does not bring any additional benefits.  Corrosiveness of peracids was PFA > commercial PAA z PPA z PAA for stainless steel 316L. The corrosion rates were low (<6 mm year
1). For carbon steel the corrosion rates were significantly higher (<500 mm year
1): PAA was least corrosive while other peracids were similar. Results indicate that carbon steel is an unsuitable material to be contact with dilute aqueous peracid solutions. Acknowledgments This study was funded by Maa-ja vesitekniikan tuki ry. The au€ivi Joensuu thors wish to thank Hanna Runtti, Hanna Prokkola, Pa and Tun Nyo for providing help in collecting samples and conducting measurements. Additionally, help with the experimental set-up from Johanna Hentunen was appreciated. References Antonelli, M., Rossi, S., Mezzanotte, V., Nurizzo, C., 2006. Secondary effluent disinfection: PAA long term efficiency. Environ. Sci. Technol. 40 (15), 4771e4775. http://dx.doi.org/10.1021/es060273f. ve, J., Impe, J.V., Dewil, R., 2011. Peracetic Appels, L., Assche, A.V., Willems, K., Degre acid oxidation as an alternative pre-treatment for the anaerobic digestion of waste activated sludge. Bioresour. Technol. 102 (5), 4124e4130. http://

dx.doi.org/10.1016/j.biortech.2010.12.070. ASTM G102-89, 2010. Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements. ASTM International, West Conshohocken, PA. http://dx.doi.org/10.1520/G0102-89R10, 2010. www. astm.org. Awad, M.I., Denggerile, A., Ohsaka, T., 2004. Electroreduction of peroxyacetic acid at gold electrode in aqueous media. J. Electrochem. Soc. 151 (12), E358eE363. http://dx.doi.org/10.1149/1.1812733. Azzellino, A., Antonelli, M., Canziani, R., Malpei, F., Marinetti, M., Nurizzo, C., 2011. Multivariate modelling of disinfection kinetics: a comparison among three different disinfectants. Desalin. Water Treat. 29 (1e3), 128e139. http:// dx.doi.org/10.5004/dwt.2011.1610. Baldry, M.G.C., 1983. The bactericidal, fungicidal and sporicidal properties of hydrogen peroxide and peracetic acid. J. Appl. Bacteriol. 54 (3), 417e423. http:// dx.doi.org/10.1111/j.1365-2672.1983.tb02637.x. Cavallini, G.S., Campos, S. X. d., Souza, J. B. d., Vidal, Carlos Magno de Sousa, 2013. Comparison of methodologies for determination of residual peracetic acid in wastewater disinfection. Int. J. Environ. Anal. Chem. 93 (8), 906e918. http:// dx.doi.org/10.1080/03067319.2012.702274. Chhetri, R.K., Flagstad, R., Munch, E.S., Hørning, C., Berner, J., Kolte-Olsen, A., Thornberg, D., Andersen, H.R., 2015. Full scale evaluation of combined sewer overflows disinfection using performic acid in a sea-outfall pipe. Chem. Eng. J. 270, 133e139. http://dx.doi.org/10.1016/j.cej.2015.01.136. € Chhetri, R.K., Thornberg, D., Berner, J., Gramstad, R., Ojstedt, U., Sharma, A.K., Andersen, H.R., 2014. Chemical disinfection of combined sewer overflow waters using performic acid or peracetic acids. Sci. Total Environ. 490, 1065e1072. http://dx.doi.org/10.1016/j.scitotenv.2014.05.079. Chick, H., 1908. An investigation of the laws of disinfection. J. Hyg. 8 (01), 92e158. http://dx.doi.org/10.1017/S0022172400006987. Collivignarelli, C., Bertanza, G., Pedrazzani, R., 2000. A comparison among different wastewater disinfection systems: experimental results. Environ. Technol. 21 (1), 1e16. http://dx.doi.org/10.1080/09593332108618137. Crebelli, R., Conti, L., Monarca, S., Feretti, D., Zerbini, I., Zani, C., Veschetti, E., Cutilli, D., Ottaviani, M., 2005. Genotoxicity of the disinfection by-products resulting from peracetic acid- or hypochlorite-disinfected sewage wastewater. Water Res. 39 (6), 1105e1113. http://dx.doi.org/10.1016/j.watres.2004.12.029. Dell'Erba, A., Falsanisi, D., Liberti, L., Notarnicola, M., Santoro, D., 2007. Disinfection by-products formation during wastewater disinfection with peracetic acid. Desalination 215 (1e3), 177e186. http://dx.doi.org/10.1016/j.desal.2006.08.021. Directive 2006/7/EC of the European Parliament and of the Council of 15 February 2006 concerning the management of bathing water quality and repealing Directive 76/160/EEC, OJ L64, 2006, 37e51 Falsanisi, D., Gehr, R., Santoro, D., Dell'Erba, A., Notarnicola, M., Liberti, L., 2006. Kinetics of PAA demand and its implications on disinfection of wastewaters. Water Qual. Res. J. Can. 41 (4), 398e409. Flores, M.J., Lescano, M.R., Brandi, R.J., Cassano, A.E., Labas, M.D., 2014. A novel approach to explain the inactivation mechanism of Escherichia coli employing a commercially available peracetic acid. Water Sci. Technol. 69 (2), 358e363. http://dx.doi.org/10.2166/wst.2013.721. Gagnon, C., Lajeunesse, A., Cejka, P., Gagne, F., Hausler, R., 2008. Degradation of selected acidic and neutral pharmaceutical products in a primary-treated wastewater by disinfection processes. Ozone Sci. Eng. 30 (5), 387e392. http:// dx.doi.org/10.1080/01919510802336731. Gehr, R., Chen, D., Moreau, M., 2009. Performic acid (PFA): tests on an advanced primary effluent show promising disinfection performance. Water Sci. Technol. 59 (1), 89e96. http://dx.doi.org/10.2166/wst.2009.761. Greenspan, F.P., Mackellar, D.G., 1948. Analysis of aliphatic per acids. Anal. Chem. 20 (11), 1061e1063. http://dx.doi.org/10.1021/ac60023a020. Gunter, L., Heinrich, R., Kurt, S. 1969. Process for stabilizing solutions of aliphatic percarboxylic acids. US Patent 3442937A. k, L.L., Finch, G.R., 1998. Modeling water treatment chemical disinfection kiGyüre netics. J. Environ. Eng. 124 (9), 783e793. http://dx.doi. org/10.1061/(ASCE)07339372(1998)124:9(783). Hagman, M., Heander, E., Jansen, J. l. C., 2008. Advanced oxidation of refractory organics in leachateepotential methods and evaluation of biodegradability of the remaining substrate. Environ. Technol. 29 (9), 941e946. http://dx.doi.org/ 10.1080/09593330801985057. Hey, G., Ledin, A., Jansen, J.L.C., Andersen, H.R., 2012. Removal of pharmaceuticals in biologically treated wastewater by chlorine dioxide or peracetic acid. Environ. Technol. 33 (9), 1041e1047. http://dx.doi.org/10.1080/09593330.2011.606282. Hom, L.W., 1972. Kinetics of chlorine disinfection in an ecosystem. J. Sanit. Eng. Div. 98 (1), 183e194. Jones, C.W., 1999. Applications of Hydrogen Peroxide and Derivatives. Royal Society of Chemistry, Cambridge. € Karpova, T., Pekonen, P., Gramstad, R., Ojstedt, U., Laborda, S., Heinonen-Tanski, H., vez, A., Jime nez, B., 2013. Performic acid for advanced wastewater disinCha fection. Water Sci. Technol. 68 (9), 2090e2096. http://dx.doi.org/10.2166/ wst.2013.468. Kitis, M., 2004. Disinfection of wastewater with peracetic acid: a review. Environ. Int. 30 (1), 47e55. http://dx.doi.org/10.1016/S0160-4120(03)00147-8. Koivunen, J., Heinonen-Tanski, H., 2005. Peracetic acid (PAA) disinfection of primary, secondary and tertiary treated municipal wastewaters. Water Res. 39 (18), 4445e4453. http://dx.doi.org/10.1016/j.watres.2005.08.016. Kunigk, L., Gomes, D.R., Forte, F., Vidal, K.P., Gomes, L.F., Sousa, P.F., 2001. The influence of temperature on the decomposition kinetics of peracetic acid in

T. Luukkonen et al. / Water Research 85 (2015) 275e285 solutions. Braz. J. Chem. Eng. 18 (2), 217e220. http://dx.doi.org/10.1590/S010466322001000200009. Liberti, L., Notarnicola, M., 1999. Advanced treatment and disinfection for municipal wastewater reuse in agriculture. Water Sci. Technol. 40 (4e5), 235e245. http:// dx.doi.org/10.1016/S0273-1223(99)00505-3. ~o, L., Hecquet, G., Pralus, C., Requieme, B., Schirmann, J., 2002. Lion, C., Da Conceiça Destruction of toxic organophosphorus and organosulfur pollutants by perpropionic acid: the first stable, industrial liquid water-miscible peroxyacid in decontamination. New J. Chem. 26 (10), 1515e1518. http://dx.doi.org/10.1039/ B201083F. Littlejohn, D., Chang, S.G., 1990. Removal of nitrogen oxides (NOx) and sulfur dioxide from flue gas by peracid solutions. Ind. Eng. Chem. Res. 29 (7), 1420e1424. http://dx.doi.org/10.1021/ie00103a047. €mo €, J., Lassi, U., 2014. Chemical aspects Luukkonen, T., Teeriniemi, J., Prokkola, H., Ra of peracetic acid based wastewater disinfection. Water SA 40 (1), 73e80. http:// dx.doi.org/10.4314/wsa.v40i1.9. Mattila, T. and Aksela, R. 2000. Method for the preparation of aqueous solutions containing performic acid as well as their use. US Patent 6049002. k, J., 1968. Antifungal properties of performic and perpropionic Merka, V., Dvora acids. J. Hyg. Epidemiol. Microbiol. Immunol. 12 (1), 115e121. Merka, V., Sita, F., Zikes, V., 1965. Performic and perpropionic acids as disinfectants in comparison with peracetic acid. J. Hyg. Epidemiol. Microbiol. Immunol. 59, 220e226. Meyer, E., 1976. Disinfection of sewage waters from rendering plants by means of peracetic acid. J. Hyg. Epidemiol. Microbiol. Immunol. 20 (3), 266e273. Mijangos, F., Varona, F., Villota, N., 2006. Changes in solution color during phenol oxidation by fenton reagent. Environ. Sci. Technol. 40 (17), 5538e5543. http:// dx.doi.org/10.1021/es060866q. Nurizzo, C., Bonomo, L., Malpei, F., 2001. Some economic considerations on wastewater reclamation for irrigation, with reference to the Italian situation. Water Sci. Technol. 43 (10), 75e81. Nurizzo, C., Antonelli, M., Profaizer, M., Romele, L., 2005. By-products in surface and reclaimed water disinfected with various agents. Desalination 176 (1e3 Spec. Iss.), 241e253. http://dx.doi.org/10.1016/j.desal.2004.11.012. Pedersen, L., Meinelt, T., Straus, D.L., 2013. Peracetic acid degradation in freshwater aquaculture systems and possible practical implications. Aquac. Eng. 53, 65e71. http://dx.doi.org/10.1016/j.aquaeng.2012.11.011. Profaizer, M., 1998. Aspetti modellistici e tecniche alternative nella disinfezione di acque potabili: l'acido peracetico (PhD. thesis). Politecnico di Milano, Italy. Qu, Q., Jiang, S., Li, L., Bai, W., Zhou, J., 2008. Corrosion behavior of cold rolled steel in peracetic acid solutions. Corros. Sci. 50 (1), 35e40. http://dx.doi.org/10.1016/ j.corsci.2007.06.008. Ragazzo, P., Chiucchini, N., Bottin, F., 20e23 May, 2007. The use of hyproform disinfection system in wastewater treatment: batch and full scale trials. In:

285

Chemical Water and Wastewater Treatment IX: Proceedings of the 12th Gothenburg Symposium 2007, p. 267. Ljubljana, Slovenia. Ragazzo, P., Chiucchini, N., Piccolo, V., Ostoich, M., 2013. A new disinfection system for wastewater treatment: performic acid full-scale trial evaluations. Water Sci. Technol. 67 (11), 2476e2487. http://dx.doi.org/10.2166/wst.2013.137. Rokhina, E.V., Makarova, K., Golovina, E.A., Van As, H., Virkutyte, J., 2010. Free radical reaction pathway, thermochemistry of peracetic acid homolysis, and its application for phenol degradation: spectroscopic study and quantum chemistry calculations. Environ. Sci. Technol. 44 (17), 6815e6821. http://dx.doi.org/ 10.1021/es1009136. Rossi, S., Antonelli, M., Mezzanotte, V., Nurizzo, C., 2007. Peracetic acid disinfection: a feasible alternative to wastewater chlorination. Water Environ. Res. 79 (4), 341e350. http://dx.doi.org/10.2175/106143006X101953. Rothbart, S., Ember, E.E., Van Eldik, R., 2012. Mechanistic studies on the oxidative degradation of orange II by peracetic acid catalyzed by simple manganese(ii) salts. Tuning the lifetime of the catalyst. New J. Chem. 36 (3), 732e748. http:// dx.doi.org/10.1039/C2NJ20852K. Santoro, D., Gehr, R., Bartrand, T.A., Liberti, L., Notarnicola, M., Dell'Erba, A., Falsanisi, D., Haas, C.N., 2007. Wastewater disinfection by peracetic acid: assessment of models for tracking residual measurements and inactivation. Water Environ. Res. 79 (7), 775e787. http://dx.doi.org/10.2175/ 106143007X156817. SFS-EN ISO 7899-2, 2000. Water Quality. Detection and Enumeration of Intestinal Enterococci. Part 2: Membrane Filtration Method. SFS-EN ISO 9308-1, 2014. Water Quality. Enumeration of Escherichia coli and Coliform Bacteria. Part 1: Membrane Filtration Method for Waters with Low Bacterial Background Flora. Swern, D., 1949. Organic peracids. Chem. Rev. 45 (1), 1e68. http://dx.doi.org/ 10.1021/cr60140a001. Vandenberg, L.N., Hauser, R., Marcus, M., Olea, N., Welshons, W.V., 2007. Human exposure to bisphenol A (BPA). Reprod. Toxicol. 24 (2), 139e177. http:// dx.doi.org/10.1515/reveh-2012-0034. Vimont, A., Fliss, I., Jean, J., 2014. Study of the virucidal potential of organic peroxyacids against norovirus on food-contact surfaces. Food Environ. Virol. 7 (1), 49e57. http://dx.doi.org/10.1007/s12560-014-9174-0. Watson, H.E., 1908. A note on the variation of the rate of disinfection with change in the concentration of the disinfectant. J. Hyg. 8 (04), 536e542. http://dx.doi.org/ 10.1017/S0022172400015928. Yousefzadeh, S., Nabizadeh, R., Mesdaghinia, A., Nasseri, S., Hezarkhani, P., Beikzadeh, M., Valadi Amin, M., 2014. Evaluation of disinfection efficacy of performic acid (PFA) catalyzed by sulfuric and ascorbic acids tested on Escherichia coli (ATCC, 8739). Desalin. Water Treat. 52 (16e18), 3280e3289. http://dx.doi.org/10.1080/19443994.2013.799047.