Adsorption Capacity of a Volcanic Rock—Used in ConstructedWetlands—For Carbamazepine Removal, and Its Modification with Biofilm Growth

Abstract

Abstract:In this study, the aim was to evaluate the adsorption capacity of a volcanic rock commonly used in Mexico as filter medium in constructed wetlands (locally named tezontle) for carbamazepine (CBZ) adsorption, as well as to analyze the change in its capacity with biofilm growth. Adsorption essays were carried out under batch conditions by evaluating two particle sizes of tezontle, two values of the solution pH, and two temperatures; from these essays, optimal conditions for carbamazepine adsorption were obtained. The optimal conditions (pH 8, 25 • C and 0.85-2.0 mm particle-size) were used to evaluate the adsorption capacity of tezontle with biofilm, which was promoted through tezontle exposition to wastewater in glass columns, for six months. The maximum adsorption capacity of clean tezontle was 3.48 µg/g; while for the tezontle with biofilm, the minimum value was 1.75 µg/g (after the second week) and the maximum, was 3.3 µg/g (after six months) with a clear tendency of increasing over time. The adsorption kinetic was fitted to a pseudo-second model for both tezontle without biofilm and with biofilm, thus indicating a chemisorption process. On clean tezontle, both acid active sites (AAS) and basic active sites (BAS) were found in 0.087 and 0.147 meq/g, respectively. The increase in the adsorption capacity of tezontle with biofilm, along the time was correlated with a higher concentration of BAS, presumably from a greater development of biofilm. The presence of biofilm onto tezontle surface was confirmed through FTIR and FE-SEM. These results confirm the essential role of filter media for pharmaceutical removal in constructed wetlands (CWs).

Development of Heliconia latispatha in constructed wetlands, for the treatment of swine/domestic wastewater in tropical climates, with PET as a substitute for the filter medium

“…Interestingly, the results on phosphorus removal are very low in comparison to the 44.3 to 63.4% obtained by Sandoval-Herazo et al (2021a) with the same wastewater but using tezontle as filter medium. These results corroborate the role of tezontle in the removal of phosphorus, which due to its structural and textural properties (Tejeda et al, 2017) not only allow direct interaction with phosphorus by chemical and physical adsorption, but also probably favor the development of increased populations of microorganisms that contribute to phosphorus uptake and retention; these removal mechanisms are not possible (or occur to a lesser extent) when PET is used as substrate and therefore phosphorus removal is lower in this study. In addition, the higher removal in vegetated systems indicates that flower harvesting could contribute to long-term phosphorus removal.…”

Removing Organic Matter and Nutrients from Pig Farm Wastewater with a Constructed Wetland System

“…Total porosity reported in other studies ranges from 67% to 74.7%, with aeration porosity levels of 39.2–44.4% and real density of 2.45 g·cm −3 [ 29 , 30 ]. Other studies have reported an average pore diameter of 26.24 nm and apparent porosity/void space of 56.2% [ 31 ]. After the tezontle, another layer of sand was placed as a substrate for the vegetation.…”

Constructed Wetlands in Latin America and the Caribbean: A Review of Experiences during the Last Decade

“…The influence of the plants in the general performance of the CWs has been evaluated in many of the studies, but also the use of the plants as an ornamental element [122]. The role of the filling media and its capacity for phosphorus removal [116], and the removal of elements [165] has been reported. Some of the studies tackle hydraulics [71,111,128], clogging phenomena [112], kinetics for nutrient removal [47] and flow patterns [143].…”