Abstract
In this research, the removal of cadmium (Cd) from simulated wastewater was investigated by using a fixed bed bio-electrochemical reactor. The effects of the main controlling factors on the performance of the removal process such as applied cell voltage, initial Cd concentration, pH of the catholyte, and the mesh number of the cathode were investigated. The results showed that the applied cell voltage had the main impact on the removal efficiency of cadmium where increasing the applied voltage led to higher removal efficiency. Meanwhile increasing the applied voltage was found to be given lower current efficiency and higher energy consumption. No significant effect of initial Cd concentration on the removal efficiency of cadmium but increasing the initial concentration would be given higher current efficiency and lower energy consumption. The results established that using a pH value lower than three results in a sharp decrease in the removal efficiency as well as using a pH value higher than seven results in decreasing the removal efficiency. Using a mesh number higher than 30 gave a lower removal efficiency. The best operating conditions were found to be an applied potential of 1.8 V, an initial Cd concentration of 125 ppm, and a pH of 7. Under these operating conditions with the using a stack of stainless with mesh number 30 as a packed bed cathode, a complete removal efficiency of Cd(100%) was obtained at a current efficiency of 83.57% and energy consumption of 0.57 kWh/kg Cd.
Highlights
Pollution of the environment by heavy metals such as cadmium, lead, cobalt, nickel, zinc, and copper is a serious environmental and health hazard since these metals are toxic and nonbiodegradable
We investigated the removal of cadmium using a new design of microbial electrolysis cells (MECs) composed of a fixed bed of parallel stainless steel screens as a cathode and porous graphite as an anode with the using locally soil material as a source of bacteria
4.CONCLUSIONS The results of the present work confirmed the possibility of the complete cadmium removal from simulated wastewater using a fixed bed bio-electrochemical reactor
Summary
Pollution of the environment by heavy metals such as cadmium, lead, cobalt, nickel, zinc, and copper is a serious environmental and health hazard since these metals are toxic and nonbiodegradable They have the affinity to bio-accumulate through the food chain even at low concentrations leading to many diseases and disorders (Amarasinghe and Williams, 2007; Choi, et al, 2014). The harmful effects of cadmium involve acute and chronic metabolic disorders, such as emphysema, renal damage, hypertension, and testicular atrophy (Choi, et al, 2014) Various industrial processes, such as smelting and refining of nonferrous metals, battery manufacturing, electroplating, and inorganic pigment industry, result in cadmium contamination in wastewater streams (Kurniawan, et al, 2006). Traditional biological processes are considered as an alternative strategy to physical-chemical processes for cadmium removing via different mechanisms such as bio-sorption, enzymatic reduction, bio-mineralization, and precipitation (Bai, et al, 2008; Pagnanelli, et al, 2010)
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