Influence of the employment of adsorption and coprecipitation agents for the removal of PPCPs in conventional activated sludge (CAS) systems

Abstract

Three activated sludge reactors were operated to improve the removal of organic micropollutants such as Pharmaceutical and Personal Care Products (PPCPs). Reactor 1 (R1) was operated as a Conventional Activated Sludge reactor (CAS), Reactor 2 (R2) consisted of a CAS unit that was continuously fed with FeCl3 whereas granular activated carbon (GAC) was fed directly into the mixed liquor of Reactor 3 (R3) in order to attain concentrations in the range 100-1,000 mg/L. PPCPs removal rates varied depending on the compound present in each reactor during the entire 220 days of operation. Some substances showed the same behaviour in all reactors, such as the acidic pharmaceuticals naproxen and ibuprofen, which were almost completely removed (> 90%). More hydrophobic organic substances, like musk fragrances, were about 90% removed after 40 days of operation in all of the reactors. The main difference between the three reactors was obtained in R3 when the GAC concentrations in the aeration tank were around 500-1,000 mg/L. Under these conditions, the more recalcitrant compounds like diazepam and carbamazepine could be removed by up to 40%, and diclofenac up to 85%. Adsorption isotherms for PPCPs were obtained with activated carbon, and the results were successfully fitted to the Freundlinch equation. The more recalcitrant compounds (carbamazepine, diazepam and diclofenac) had the highest adsorption capacities onto GAC, which is consistent with the behaviour observed in R3 and helps to identify the removal mechanism (adsorption for these compounds, whereas absorption for fragrances).

Coupling granular activated carbon adsorption with membrane bioreactor treatment for trace organic contaminant removal: Breakthrough behaviour of persistent and hydrophilic compounds

“…Table 3 shows the Langmuir and Freundlich isotherm parameters (q m and K f , respectively) for the compounds that demonstrated relatively rapid breakthrough from the GAC column. Our isotherm data conform to a general trend found in the literature regarding a relatively higher adsorption capacity of the neutral compounds carbamazepine (Nowotny et al, 2007;Serrano et al, 2010;Deegan et al, 2011) and metronidazole (Rivera-Utrilla et al, 2009) in comparison to that of the ionized compounds, namely, diclofenac (Nowotny et al, 2007;Serrano et al, 2010) and naproxen (Nowotny et al, 2007;Serrano et al, 2010). However, the isotherm parameters did not demonstrate any …”

“…In the literature, several solute properties that influence the adsorption of organic contaminants onto activated carbon have been identified. These properties include, among others, solute hydrophobicity (De Ridder et al, 2010;Serrano et al, 2010), aromaticity (De Ridder et al, 2010), charge and size (De Ridder et al, 2010), and presence of specific functional groups (Westerhoff et al, 2005;De Ridder et al, 2010). The adsorption mechanisms related to these properties occur in parallel, and their respective dominance can vary from compound to compound (De Ridder et al, 2010;Dickenson and Drewes, 2010).…”

“…In addition to hydrophobic partitioning, various other mechanisms such as hydrogen bonding, π-π-interaction between aromatic rings, and van der Waals forces (e.g., dipole-dipole interaction, London dispersion force) can contribute towards the adsorption of a compound onto a specific adsorbent (Westerhoff et al, 2005;Vieno et al, 2007;De Ridder et al, 2010;Dickenson and Drewes, 2010;Serrano et al, 2010;Hernández-Leal et al, 2011). However, as noted earlier, their relative dominance will depend on specific physicochemical properties.…”

Carbamazepine as a Possible Anthropogenic Marker in Water: Occurrences, Toxicological Effects, Regulations and Removal by Wastewater Treatment Technologies

“…Kleywegt et al [244] investigated the removal of CBZ by GAC adsorption followed by UV photolysis that achieved effective removal of CBZ (93%). Serrano et al [203] investigated the removal of PhACs including CBZ in a CAS process followed by GAC adsorption. They reported that adsorption onto activated carbon improved the overall removal of CBZ by as much as 40% [203].…”

Recent Advances in Water Management: Saving, Treatment and Reuse

“…Serrano et al [203] investigated the removal of PhACs including CBZ in a CAS process followed by GAC adsorption. They reported that adsorption onto activated carbon improved the overall removal of CBZ by as much as 40% [203].…”