Abstract

Commonly used pharmaceutical products present in sewage cannot be removed by conventional wastewater treatment plants. Therefore, they can be found in effluents discharged to aquatic systems. Endocrine disrupting compounds (EDCs) are among these releases into the environment. For example, 17α-ethynylestradiol (EE2) is a synthetic compound extensively used by the population, which is released into an environment. Thus, it can cause a negative effect on the endocrine system of aquatic biota and human.
To protect the aquatic system against an impact of EDCs comprised in the effluent, a novel system for their removal was proposed. A steroidal estrogen, EE2, was assumed to be a target compound in this investigation. Then, the objective of this study is to develop a sustainable system for EE2 removal. The methodological approach combining an adsorption with electro-kinetic phenomena has been proposed. Sustainability is supposed, based on revalorization of wasted materials and minimizing of energy use. Six phases of investigation were proposed, namely, phase 1: Manufacturing procedures; phase 2: Upgraded adsorption system; phase 3: Experimental protocol; phase 4: Electro-adsorptive system; phase 5: Electro-adsorptive system comparison; phase 6; cost-effectiveness increase and energy saving proposal. The study has been advanced, where waste generated by fisheries and forestry demonstrated already excellent materials to build an electro-adsorptive system. Application of a low direct current (DC) has also demonstrated a sufficient effectiveness of the system. In focus, to understand the partitioning of EDCs (EE2) between liquid and solid phases, eight types of adsorbents made from New Adsorptive Materials were initially used to remove EE2 from an aqueous solution. Afterward, these adsorbents were enhanced with New Adsorptive Materials (chitin) to increase EE2 removal from an aqueous solution. These adsorbents were then enhanced with New Adsorptive Materials (chitin) to increase EE2 removal from an aqueous solution.
The analytical test showed that adsorption phenomena using these types of adsorbents adequately reduces EE2 in the aquatic solution. The obtained results of the analytical test were initially sorted based on the adsorbent type: 1. Adsorbent made from New Adsorptive Material (softwood) showed 42% removal of EE2; 2. Adsorbent made from New Adsorptive Material (hardwood) showed 47% removal of EE2.

As a competitive removal capacity with cost- effectiveness increase, it was proposed to enhance the best adsorbent which was shown by the primary results using chitin. This method (adsorbent enhancement method) showed 92% EE2 removal. It was a great removal capacity, but it was still far away from the research objective. Therefore, it was proposed to establish an electrical system able to support adsorption phenomena. A combination technique was the choice. This technique was established by a combining a direct current (DC) field phenomena and adsorption phenomena (Electro-Adsorptive System). In this phase, various configurations of electrokinetic reactors were tested: 1). Electrode materials iron, aluminum, and carbon; 2) Constant voltage of 5, 10, 15, 20, 30V; 3). Time of applied electrical field from 9h to 24h; 4). Different types of synthetic adsorbents. Finally, an experimental comparison was conducted between synthetic and commercial adsorbents.

The results from the analytical tests were as follows: 1) 82 % removal of EE2 at pH between 7 to 10 using the individual formulated adsorbent from thermally treated hardwood residues (H1T1) (far from the objective with some disadvantages); 2) 99.99% removal of EE2 using the adsorbent made from chitin in electro-adsorptive system regardless electrodes types, which are a good indicator for electrode flexibility use but the disadvantage of this removal method is remaining particles of adsorbent in an aqueous solution; 3) 79% removal of EE2 using the commercial activated carbon adsorbent (CACA) made from coconut shell; 4) 99.99% removal of EE2 using the enhanced adsorbent made from NAM (H1T1)+chitin (ENAM) in electro-adsorptive system (the best method).
This study has shown the possibility of the EE2 removal by 99.99%. It is expected, that the developed system would be applied to water treatment facilities or to polish effluents before discharge into aquatic systems.