The effect of constructed wetland with different filling materials integrated with fuel cell on wastewater removal and bioelectric generation potential

In the Ph.D. thesis research, wastewater treatment and simultaneously bioelectricity generation was evaluated by designing fuel cell integrated with up-flow constructed wetland with different filling materials. The aim of this study was to investigate the effect of different filler materials on the wastewater treatment process and bioelectricity production potential in CW - FC systems and to determine the most efficient filler type for higher wastewater treatment and higher bioelectric production performance. In this context, four mesocosm scale CW - FCs were established and the systems were tested by giving synthetically formed wastewater at appropriate concentrations. In the study carried out under natural conditions, four different filling materials (peat, sand, zeolite and volcanic cinder) were used and the potentials of these materials in integrated systems for wastewater treatment and bioelectricity generation were revealed. In the experiments carried out on integrated systems for 120 days, it was found that the CW-FC system with zeolite filling material operates at a higher efficiency in terms of both wastewater cleaning and bioelectricity potential than other systems. In this context, the average nitrate, ammonium, chemical oxygen demand and total phosphorus removal of the zeolite-based integrated system were determined as 81.1%, 93.1%, 92.1%, and 96.7%, respectively. It was introduced that the efficiency of the zeolite filler in the integrated system results from a wider specific surface area, a more porous composition, and a different framework structure. Besides, it was determined that the zeolite-based CW- FC produces a higher level of bioelectricity than the integrated systems established with other filling materials during the working period and the mean output voltage, power density, and Coulombic efficiency was recorded as 1,008 ± 0,14 V, 15 1 mWatt / m2 and 1.64% respectively. In light of these data, it was found that the catalysis of the electron flow was increased by facilitating the degradation of the organic substrate in the CW-FC integrated system of the zeolite used. As a result, the use of zeolite as a filling material in integrated systems indicates that peat, volcanic slag, and fine sand achieve higher treatment efficiency and higher bioelectric production than integrated systems.