Uso de esqueleto de coral sol na remediação ambiental: remoção de contaminantes aniônicos, fármacos e aditivos plásticos em efluentes líquidos

Abstract

The discharge of anionic contaminants such as phosphates, nitrates, fluorides, and sulphates through the discharge of untreated or insufficiently treated urban sewage and industrial effluents is associated, among other impacts, with eutrophication of water bodies. In addition to these inorganic contaminants, drugs, plastic additives, sunscreens, and hormones recognized as emerging micropollutants have often been detected in aqueous matrices, such as sewage, water bodies and water supply, the impacts of which are only partially known. Conventional wastewater treatment plants (WWTPs) have low efficiency in removing these contaminants, which justifies the search for sustainable treatment or polishing strategies. In Brazil, two exotic species known as Coral Sol (Tubastraea coccinea and Tubastraea tagusensis) already infest more than 3,000 km of the Brazilian coast. These species modify habitats, and once established, they can change the entire ecosystem, as they promote damage to marine biodiversity. Such species have skeletons made up of calcium carbonate, which is potentially useful in water treatment. The present study aimed to investigate the capacity for removing anionic contaminants Phosphate, Nitrate, Sulfate and Fluoride, in addition to 17 Emerging Contaminants (Benzophenone, Diethylphthalate, Sulfamethoxazole, Diazepam, Trimethoprim, Levonorgestrel, Bromazepam, Clonazepam, Ibuprofen, Bisfenol A, Bisfenol Ad16, 17- Ethinyl Estradiol, Carbamazepine, Bisphenol S, Bisphenol F, Bisphenol AF, 17- Estradiol and Estrone) found in synthetic and real effluents using Coral Sol skeleton powder as adsorbent in the (i) crude (CST) forms ) and (ii) chemically modified (CSQ). To investigate the efficiencies of CST and CSQ in removing anionic contaminants from water, a factorial design with central rotational composite design (DCCR) was applied. In order to optimize the process, the influence of the following independent variables was investigated: adsorbent / adsorbate ratio, pH; temperature, associated with studies of kinetics and balance in the best configurations obtained by DCCR for each material. The materials were characterized before and after the removal experiments by the techniques of DRX and MEV-EDX. The maximum removals obtained were: 9597 mg P Kg−1, 2110 mg N-NO3- Kg-1, 125015 mgSO42- Kg-1 (precipitation), 46950 mg F- Kg-1. The XRD analysis confirmed the crystallographic change from the Portlandite to Gypsum phase when in contact with sulfate ions. In the other analyzes, the Aragonite (CST) and Portlandite (CSQ) crystallographic phases were maintained. In all adsorption tests, the processes followed the model proposed by Langmuir and pseudo-second order kinetics. For emerging contaminants (drugs, hormones, and plastic additives) a dispersive liquid-liquid microextraction method (MELLD) was developed and optimized to extract these compounds in real effluents. The analytes were identified and quantified by ultra-efficient liquid chromatography (UPLC-MS / MS Waters). It is worth to highlight the removal efficiency for Diethylphthalate (99,9%), Clonazepam (99,9%), Bisphenol S (96,44%) and Sulfamethoxazole (99,9%) without the need for optimization of the treatment conditions in real treated wastewater sample. Based on these results, Coral Sol skeleton powder has proved to be a potentially sustainable alternative to be used as adsorbent and precipitating material, which can be useful in several applications, such as urban and industrial wastewater treatment and in controlling the population of Coral Sol, the possible commercial exploitation.