the increased presence in wastewaters, rivers and other aquifers is of environmental
concern. The search for new technologies that can solve the problem is imperative. This
work proposes the use of activated sludge for paracetamol (PARA) removal. Different
PARA concentrations were tested (0.4, 0.5, 0.6, 0.8, and 1 mg L-1) in a batch reactor
with a working volume of 4 L. The uptake values increased with increasing initial PARA
concentration, from 0.104 to 0.341 mg g-1, in agreement with the theoretically expected.
The removal percentage ranged from 93.3 to 98.8 decreasing with the increase on the
initial concentration. The removal mechanism is well described by the pseudo 1st order
model and pseudo 2nd order model, for all concentrations tested.info:eu-repo/semantics/publishedVersio

Ferreira, Eugénio C.

Mesquita, D. P.

Quintelas, Cristina

Universidade do Minho: RepositoriUM

WASTES: Solutions, Treatments and Opportunities 4th International Conference  September 25th – 26th 2017   REMOVAL OF PARACETAMOL BY AN ACTIVATED SLUDGE BIOREACTOR  C. Quintelas, D. Mesquita and E.C. Ferreira CEB - Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal E-mail: cquintelas@deb.uminho.pt   ABSTRACT Paracetamol is one of the most commonly used oral analgesics and antipyretics and the increased presence in wastewaters, rivers and other aquifers is of environmental concern. The search for new technologies that can solve the problem is imperative. This work proposes the use of activated sludge for paracetamol (PARA) removal. Different PARA concentrations were tested (0.4, 0.5, 0.6, 0.8, and 1 mg L-1) in a batch reactor with a working volume of 4 L. The uptake values increased with increasing initial PARA concentration, from 0.104 to 0.341 mg g-1, in agreement with the theoretically expected. The removal percentage ranged from 93.3 to 98.8 decreasing with the increase on the initial concentration. The removal mechanism is well described by the pseudo 1st order model and pseudo 2nd order model, for all concentrations tested.    Keywords: Activated sludge, kinetics, paracetamol, removal, uptake   INTRODUCTION  The presence of pharmaceuticals and their potential to cause adverse effects in the aquatic environment has been the subject of increased scientific and public interest. Different authors suggested methods to remove these compounds from aqueous systems that include biological technologies and physicochemical methods [1-3]. Several disadvantages are associated with physicochemical methods as the generation of secondary pollutants and the high operational costs. The biological methods present less disadvantages: biodegradation of pharmaceuticals is being considered as an environmentally friendly option with low-cost operational requirements and the products of degradation are innocuous end compounds such as CO2 and H2O [4]. The aim of this study was to test the use of activated sludge to remove paracetamol. Removal percentages and uptake values were calculated. . Pseudo first-order and pseudo second-order kinetics models were applied to the data to study the mechanism that controls the biological process.   MATERIALS AND METHODS  Experimental setup and synthetic medium  Experiments with different paracetamol (PARA) concentrations (0.4, 0.5, 0.6, 0.8, and 1.0 mg L-1) were conducted in a 4 L lab-scale batch reactor operated at room temperature during approximately three days. The system was inoculated with activated sludge from a domestic wastewater treatment plant where an initial mixed liquor suspended solids (MLSS) concentration of 3 g L-1 was used. Synthetic medium was fed to the system in the beginning of each experiment and contained (per liter): 2.55 g C2H3O2Na.3H2O, 0.34 g C3H5NaO2, 0.59 g NH4Cl, 0.95 g MgSO4⋅7H2O, 0.44 g CaCl2⋅2H2O, 0.03 g EDTA, and 3.16 mL of a trace metals solution. The trace metals solution [5] is listed below (g L-1): 1.5 FeCl3⋅6H2O, 0.15 H3BO3, 0.03 CuSO4⋅5H2O, 0.18 KI, 0.12 MnCl2⋅4H2O, 0.06 Na2MoO4⋅2H2O, 0.12 ZnSO4⋅7H2O, 0.15 CoCl2⋅6H2O. Compressed air was used to ensure aerobic conditions and the pH was maintained around 7 by a pH controller using two-way controller pumps dosing 0.3 M HCl or 0.3 M NaOH when the pH was above/below the set point. Samples were taken at different time intervals, centrifuged (13400 rpm for 10 min) and the aqueous phase was stored at 4ºC. Prior to analysis, the liquid samples were thawed and 78  homogenized by vortexing. The PARA concentrations were determined using a UHPLC system. All measurements were conducted in duplicate. The results presented are an average of both results. The relative standard deviation and relative error of the experimental measurements were <1% and 3%, respectively.  Analytical procedures Chromatographic analysis was performed using a Shimadzu Corporation apparatus (Tokyo, Japan) consisting of a UHPLC equipment (Nexera) with one multi- channel pump (LC-30AD), an autosampler (SIL-30AC), an oven (CTO-20AC), a diode array detector (M-20A) and a system controller (CBM-20A) with proper software (LabSolutions). A Kinetex 2.6u EVO C18 column (1504.6mm i.d.) supplied by Phenomenex, Inc. (CA, USA) was used. The mobile phase was 0.1% phosphoric acid in water (pump A) and 0.1% phosphoric acid in acetonitrile (pump B). Starting mobile phase composition was 95% A, decreased to 5% A in 9 min and increased again to 95% (9.01 min) and remains in this percentage for 3 min. The flow rate was 1.8 mL/min. The sample was monitored by the diode array detector from 190 to 400 nm, and chromatograms were extracted at 215 nm. Column oven was set at 50°C and the volume of injection was 5 µL. For solid phase extraction (SPE), the sorbent cartridges (Strata SDB-L Styrene-Divinylbenzene Polymer, 100mg/1mL) were used. The cartridges were conditioned with methanol and equilibrated with water. The sample was loaded and washed with methanol/water (5:95), dryed 10 mim under full vacuum and eluted with methanol.  Kinetic models The nonlinear form of pseudo first-order and pseudo second-order kinetics models [6] are expressed as:   𝑞𝑞 =  𝑞𝑞𝑒𝑒  (1 − 𝑒𝑒𝑒𝑒𝑒𝑒−𝑘𝑘1𝑡𝑡)      (Eq. 1)  𝑞𝑞 =  𝑘𝑘2𝑞𝑞𝑒𝑒2 𝑡𝑡1+ 𝑘𝑘2𝑞𝑞𝑒𝑒 𝑡𝑡       (Eq. 2)  The value of qe represents the uptake value (mg g-1), k1 and k2 are rate constant values, and t is time.  RESULTS AND DISCUSSION  The present study shows that a reactor inoculated with activated sludge is able to remove PARA in percentages from 93.3 and 98.8%, in approximately 73-77 h. The uptake varied from 0.104 mg g-1 to 0.341 mg/g (Table 1). As expected the uptake increase with the increase on the PARA concentration. Padmesh et al. [7] suggested that this behavior can be justified by the fact that surface saturation was dependent on the initial pharmaceutical concentration. As the concentration increase, the number of moles of PARA also increased for the same amount of available sites on the biomass.   Table 1- Uptake and removal percentage values for the different initial PARA concentration  Ci [mg L-1] Uptake [mg g-1] Removal percentage [%] 0.4 0.104 98.8 0.5 0.170 97.9 0.6 0.168 95.3 0.8 0.325 94.8 1.0 0.341 93.3  The removal percentage decrease with the increase on the initial PARA concentration and this can be explained by the fact that high concentrations reduce the average distance between the adsorbing species, affecting the charge distribution of their neighbors and altering the ability of the species to migrate to the biomass surface, resulting in reduced adsorption [8]. The correlation coefficient (R2) values suggest that both models, pseudo first-order and pseudo second-order models, fits well the removal of PARA by the reactor inoculated with activated sludge. The values of k1 and k2 (Table 2) do not follow any trend probably because the removal of PARA by the activated sludge is independent of the initial concentration. The assumptions of both models are different: pseudo first-order models assumes that the reaction rate is limited by 79  one mechanism, one class of sorbing sites and all of them of the time dependent type; pseudo second-order model assumes that the adsorption process is controlled by surface reaction, with chemisorption involving valence forces, through sharing or exchange of electrons between bacteria and pharmaceutical compounds [9]. The present results indicate that a mixed of both removal processes are involved in the removal of PARA by the activated sludge.  Table 2- Constant parameters of pseudo first and pseudo second order kinetic models  Ci Pseudo first-order model Pseudo second-order model mg/L k1 (h) R2 k2 (g mg-1 h-1) R2 0.4 0.601 0.999 30.771 0.999 0.5 0.647 0.999 37.008 0.999 0.6 0.387 0.982 54.337 0.999 0.8 1.401 0.999 124.317 0.999 1.0 0.863 0.995 24.322 0.995  These results are very promising for a future large-scale implementation of this technology.   References  [1] S. Yang, F.I. Hai, W.E. Price, J. McDonald, S.J. Khan, L.D. Nghiem, Occurrence of trace organic contaminants in wastewater sludge and their removals by anaerobic digestion, Bioresource Technol. 210 (2016) 153-159. [2] H. Khazri, I.Ghorbel-Abid, R. Kalfat, M. Trabelsi-Ayadi, Removal of ibuprofen, naproxen and carbamazepine in aqueous solution onto natural clay: equilibrium, kinetics, and thermodynamic study, Appl. Water Sci. (2016) 1-10. [3] O. Chedeville, A. Di Giusto, S. Delpeux, B. Cagnon, Oxidation of pharmaceutical compounds by ozonation and ozone/activated carbon coupling: a kinetic approach, Desalin. Water Treat. 57 (2016) 18956-18963. [4] S. Wu, L. Zhang, J. Chen, Paracetamol in the environment and its degradation by microorganisms, Appl. Microbiol. Biotechnol. 96 (2012) 875–884. [5] G.J.F. Smolders, J. van de Meij, M.C.M. van Loosdrecht, J.J. Heijnen, Model of the anaerobic metabolism of the biological phosphorus removal process: Stoichiometry and pH influence, Biotechnol. Bioeng. 43 (1994) 461-470. [6] K.V. Kumar, Linear and non-linear regression analysis for the sorption kinetics of methylene blue onto activated carbon, J. Hazard. Mater. B137 (2006) 1538–1544. [7] T.V.N. Padmesh, K. Vijayaraghavan, G. Sekaran, M. Velan, Biosorption of acid blue 15 using fresh water macroalga Azolla filiculoides: batch and column studies, Dyes Pigm. 71 (2006) 77–82. [8] C. Quintelas, F. Costa, T. Tavares, Bioremoval of diethylketone by the synergistic combination of microorganisms and clays: uptake, removal and kinetic studies, Environ. Sci. Pollut. Res. 20 82013) 1374–1383. [9] L.L. Zhang, J Hu, R.Y. Zhu, Q.W. Zhou, J.M. Chen, Degradation of paracetamol by pure bacterial cultures and their microbial consortium, Appl. Microbiol. Biotechnol. 97 (2013) 3687–3698.    80  

Removal of paracetamol by an activated sludge bioreactor

Abstract

Similar works

Full text

Available Versions

Universidade do Minho: RepositoriUM