Combined Granular Activated Carbon And UV/H₂O₂Processes For The Treatment Of Pharmaceutical Wastewater

The treatment of pharmaceutical wastewater was performed at the lab scale using UV/H₂O₂, process granular activated carbon (GAC) adsorption and their combination to investigate the total organic carbon (TOC) removal efficiency for different inlet TOC loadings and treatment times. Experimental study revealed that GAC adsorption alone had 81% efficiency in TOC removal in 10 min breakthrough time for flow rate of 0.6 L/min with granular activated carbon dosage of 333.33 mgActivated Carbon/L whereas UV/H₂O₂ process alone showed 26 and 29% TOC reduction at with 21.7 g/LH₂O₂ concentration with 254 and 185 nm wavelength lamps a 6 h hydraulic retention time, respectively, with average feed concentration (TOC) of 1,7555.75 mgC/L and COD of 5,214.6 mg/L at 25 ± 5°C. Experimental results showed that the optimum H₂O₂ dosage for the UV/H₂O₂ process was 1:2 stoichiometric COD: H₂O₂ molar ratio to achieve up to 26 and 29% TOC reduction efficiency than that at pH 12.01 which resulted 15-20% TOC reduction efficiency. The Bohart-Adams rate constants (K) and maximum adsorption capacity of carbon (N) from column breakthrough studies for synthetic pharmaceutical wastewater at 81% were found to be 7.10 x 10⁻³ L/(min.mgC) and 1.06 x 10³ mgC/L, respectively. In combined processes, it was found that GAC adsorption followed by desorption of contaminants from GAC by steam and UV₂₅₄/H₂O₂ treatment of the condensed steam let to 81% of TOC removal from the wastewater. Out of 358.73 mgC/L of TOC desorbed 88.1% of TOC was degraded in the UV₂₅₄/H₂O₂ treatment was degradation. Total operating cost of GAC adsortpion followed by desorption of contaminants from GAC by steam and UV₂₅₄/H₂O₂ treatment of condensed steam were found to be $11/L. While the pre-treated wastewater by UV₂₅₄H₂O₂ treatment followed by GAC adsorption, along the desorption of contaminants from GAC using steam and UV₂₅₄/H₂O₂ treatment of the condensed steam, let to an overall 81% TOC removal and 75.1% of TOC degradation using UV₂₅₄/H₂O₂ process. The cost of this combined treatment was found to be $6/L of wastewater treated which led to an economical saving of $5/L with respect to the combined TOC removal and degradation efficiency achieved. The savings predictions were achieved due to the less carbon dosage requirement and ability of UV/H₂O₂ process to degrade the TOC present in the wastewater. Based on single and combined treatments, the minimum total cost and time for 81% TOC removal were determined for the combination of UV₂₅₄/H₂O₂ treatment followed by GAC adsorption, along with desorption of contaminants from GAC using steam and UV₂₅₄/H₂O₂ treatment of the condensed steam. The overall minimum cost and minimum time were found to be $6/L of wastewater treated and 114.5 h, respectively. The treatment parameters and conditions for treating 30 L of the synthetic pharmaceutical wastewater were at an average feed concentration of TOC = 1,755.75 mgC/L and COD = 5,214.6 mg/L leading to TOC = 333.5 mgC/L of the effluent concentration which was near to the industrial effluent disposal level in Canada.

Combined Granular Activated Carbon And UV/H₂O₂Processes For The Treatment Of Pharmaceutical Wastewater

The treatment of pharmaceutical wastewater was performed at the lab scale using UV/H₂O₂, process granular activated carbon (GAC) adsorption and their combination to investigate the total organic carbon (TOC) removal efficiency for different inlet TOC loadings and treatment times. Experimental study revealed that GAC adsorption alone had 81% efficiency in TOC removal in 10 min breakthrough time for flow rate of 0.6 L/min with granular activated carbon dosage of 333.33 mgActivated Carbon/L whereas UV/H₂O₂ process alone showed 26 and 29% TOC reduction at with 21.7 g/LH₂O₂ concentration with 254 and 185 nm wavelength lamps a 6 h hydraulic retention time, respectively, with average feed concentration (TOC) of 1,7555.75 mgC/L and COD of 5,214.6 mg/L at 25 ± 5°C. Experimental results showed that the optimum H₂O₂ dosage for the UV/H₂O₂ process was 1:2 stoichiometric COD: H₂O₂ molar ratio to achieve up to 26 and 29% TOC reduction efficiency than that at pH 12.01 which resulted 15-20% TOC reduction efficiency. The Bohart-Adams rate constants (K) and maximum adsorption capacity of carbon (N) from column breakthrough studies for synthetic pharmaceutical wastewater at 81% were found to be 7.10 x 10⁻³ L/(min.mgC) and 1.06 x 10³ mgC/L, respectively. In combined processes, it was found that GAC adsorption followed by desorption of contaminants from GAC by steam and UV₂₅₄/H₂O₂ treatment of the condensed steam let to 81% of TOC removal from the wastewater. Out of 358.73 mgC/L of TOC desorbed 88.1% of TOC was degraded in the UV₂₅₄/H₂O₂ treatment was degradation. Total operating cost of GAC adsortpion followed by desorption of contaminants from GAC by steam and UV₂₅₄/H₂O₂ treatment of condensed steam were found to be $11/L. While the pre-treated wastewater by UV₂₅₄H₂O₂ treatment followed by GAC adsorption, along the desorption of contaminants from GAC using steam and UV₂₅₄/H₂O₂ treatment of the condensed steam, let to an overall 81% TOC removal and 75.1% of TOC degradation using UV₂₅₄/H₂O₂ process. The cost of this combined treatment was found to be $6/L of wastewater treated which led to an economical saving of $5/L with respect to the combined TOC removal and degradation efficiency achieved. The savings predictions were achieved due to the less carbon dosage requirement and ability of UV/H₂O₂ process to degrade the TOC present in the wastewater. Based on single and combined treatments, the minimum total cost and time for 81% TOC removal were determined for the combination of UV₂₅₄/H₂O₂ treatment followed by GAC adsorption, along with desorption of contaminants from GAC using steam and UV₂₅₄/H₂O₂ treatment of the condensed steam. The overall minimum cost and minimum time were found to be $6/L of wastewater treated and 114.5 h, respectively. The treatment parameters and conditions for treating 30 L of the synthetic pharmaceutical wastewater were at an average feed concentration of TOC = 1,755.75 mgC/L and COD = 5,214.6 mg/L leading to TOC = 333.5 mgC/L of the effluent concentration which was near to the industrial effluent disposal level in Canada.

DOM removal is more important than the specific DOM removal pretreatment process for GAC adsorption of TrOCs

For high levels of TrOC removal by GAC, reducing DOC0 concentration is more important than the specific DOM removal pretreatment process.

Parallel study on removal efficiency of pharmaceuticals and PFASs in advanced water treatment processes: Ozonation, GAC adsorption, and RO processes

We aimed to assess the removal efficiencies of four pharmaceuticals (carbamazepine, crotamiton, metformin, and sulfamethoxazole) and four poly- and perfluoroalkyl substances (PFASs) (PFHxA, PFHxS, PFOA, and PFOS) by lab-scale ozonation, granular activated carbon (GAC) adsorption, and reverse osmosis (RO) membrane processes under varying operating conditions. Ozonation and GAC adsorption processes were conducted at two temperatures (5 and 25°C) and three pH conditions (3, 7, and 11). The membrane process was performed using an unstirred cell with two different RO membranes. The most pharmaceuticals were effectively removed by ozonation, whereas metformin and PFASs were unaffected due to their stable chemical structures. In the GAC process, metformin was hardly removed under acidic conditions but it was enhanced by over 90%. PFASs were effectively removed by GAC adsorption and RO membrane processes. The RO membrane for brackish water treatment showed higher rejection than that for residential water treatment. Moreover, the rejection of PFAS increased as the molecular weight increased. A strategy was found to effectively remove the remaining metformin in most advanced water treatment processes. Chemically persistent PFASs were hardly removed by the ozonation process but were effectively removed by physical treatments such as GAC adsorption and RO membrane processes.

Characterization of landfill leachate by spectral-based surrogate measurements during a combination of different biological processes and activated carbon adsorption

Surrogate measurements based on excitation-emission matrix fluorescence spectra (EEMs) and ultraviolet-visible absorption spectra (UV-vis) were used to monitor the evolution of dissolved organic matter (DOM) in landfill leachate during a combination of biological and physical-chemical treatment consisting of partial nitritation-anammox (PN-Anammox) or nitrification-denitrification (N-DN) combined with granular active carbon adsorption (GAC). PN-Anammox resulted in higher nitrogen removal (81%), whereas N-DN required addition of an external carbon source to increase nitrogen removal from 24% to 56%. Four DOM components (C1 to C4) were identified by excitation-emission matrix-parallel factor analysis (EEM-PARAFAC). N-DN showed a greater ability to remove humic-like components (C1 and C3), while the protein-like component (C4) was better removed by PN-Anammox. Both biological treatment processes showed limited removal of the medium molecular humic-like component (C2). In addition, the synergistic effect of biological treatments and adsorption was studied. The combination of PN-Anammox and GAC adsorption could remove C4 completely and also showed a good removal efficiency for C1 and C2. The Thomas model of adsorption revealed that GAC had the maximum adsorption capacity for PN-Anammox treated leachate. This study demonstrated better removal of nitrogen and fluorescence DOM by a combination of PN-Anammox and GAC adsorption, and provides practical and technical support for improved landfill leachate treatment.

Evaluation of Dissolved Organic Matter Removal Characteristics in GAC Adsorption Process in Drinking Water Treatment Process using LC-OCD-OND

Objectives:In this study, we used liquid chromatograph-organic carbon detector-organic nitrogen detector (LC-OCD-OND) to evaluate adsorption and breakthrough characteristics of NOM fractions (biopolymers (BP), humic substances (HS), building blocks (BB) and low molecular weight organic substances (LMW-O)) according to the various characteristics of the different materials of granular activated carbons (GACs).Methods:Breakthrough characteristics, adsorption capacity and partition coefficients were evaluated by NOM fractions (BP, HS, BB, and LMW-O) using a lab-scale GAC adsorption column filled with coal-, coconut- and wood-based GAC. The GAC column test was operated with 10 minutes empty bed contact time (EBCT). The pore characteristics of each GAC were evaluated using an automated gas sorption analyzer (Autosorb iQ3, Quantachrome, USA) and the concentrations of NOM fractions in the influent and effluent were analyzed using chromatography LC-OCD-OND (Model 8, DOC-Labor, Germany).Results and Discussion:NOM adsorption capacity was evaluated for different materials of laboratory scale GAC adsorption column test. To study the adsorption behavior of individual NOM fractions according to the operation time, NOM was fractionated into BP, HS, BB and LMW-O by LC-OCD-OND, and the individual NOM fractions were quantified. Higher MW like BP was not adsorbed to GAC, in contrast, HS, BB, and LMW-O were well removed during the initial operation period, the concentrations in the effluent gradually increased as increase the operation period until reaching to the pseudo steady-state. Poor removal of BP in GAC adsorption may be a result of blocking the pores with large MW BP and hinder the access to the pores. However, in the case of HS, BB, and LMW-O, as the molecular size decreased, these organic matters easily access to the pores inside of GAC. It was confirmed through the partition coefficient that the adsorption capacity of these NOM fractions increased in proportion to the MW. In addition, in order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pH_zpc must be higher than the neutral pH level.Conclusions:In order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pH_zpc must be higher than the neutral pH level. In addition, in the NOM fractions, BP were not adsorbed to GAC, while the adsorption capacity of the remaining NOM fractions increased as the MW of the NOM fractions decreased. LMW-O was the most adsorbed, followed by BB, HS and BP. BP and HS play an important role in the membrane fouling that are introduced a lot into domestic and foreign water treatment plants. This study showed that the BP was not removed by the adsorption mechanism of the GAC process. In addition, HS was adsorbed and removed at the beginning of the operation, but the adsorption capacity of HS decreased rapidly as the operation period increased compared to other NOM fractions. Therefore, the GAC adsorption process is not expected to be an effective pre-treatment technology for reducing membrane foulants. Previous studies showed that the yields of DBPs (µmol･DBP/µmol･C) in the high MW humic and low MW non-humic fractions are similar. Therefore, it is suggested that the GAC adsorption process is more effective for DBP precursor control in water containing a larger percentage of LMW NOM.