Abstract
The main aim of this chapter is to conduct a simple literature review on treatment wastewaters from pharmaceutical and related industries and establish efficacies of electrochemical treatment technique in removing selected pollutants form raw wastewater. Synthetic (simulated) wastewaters were prepared using standard methods. Fractional factorial (2K - P -1) experiments were utilized at random to determine influence of selected factors (separation distance between the electrodes, volume of the wastewater used, applied current, temperature of the wastewater, treatment time, concentration of the pollutant, concentration calcium of hypochrite (Ca(OCl)2) added and depth of the electrode into the wastewater used) on efficiency of electrochemical process in removing Biochemical Oxygen Demand concentration at five (BOD5). Industrial wastewaters were collected from industrial sources within the country (Nigeria). The industrial wastewaters collected were subjected to electrochemical treatment and chemical treatments individually and in combinations under specified treatment conditions.
TopBackground
Carbon resin electrodes were developed from used dry cells (Oke et al., 2007a, b and c). Electrolysing equipment was developed from local materials. Synthetic (simulated) wastewaters were prepared using procedures and methods specified in APHA (1998). Fractional factorial (2K - P -1) experiments were utilized at random to determine influence of selected factors (separation distance between the electrodes, volume of the wastewater used, applied current, temperature of the wastewater, treatment time, concentration of the pollutant, concentration calcium of hypochrite (Ca(OCl)2) added and depth of the electrode into the wastewater used) on efficiency of electrochemical process in removing Biochemical Oxygen Demand concentration at five days (BOD5) as follow-up on previous study (Oke et al., 2007c). The choice of the parameters to be studied was done on the basis of the theoretical data about several factors that determine the efficiency of an electrochemical method and the scarce knowledge concerning carbon-resin / aluminium electrodes. An electrochemical treatment plant on a laboratory scale using public electricity source was setup (Figures 1a and b). BOD5 determinations in wastewaters were carried out following procedures in APHA (1998) using respirometric method (CAMLAB HACH, model number 2173B BOD manufactured by Hach Chemical Company). The procedures and steps were repeated for blanks (to serve as controls). Efficacies of the system were computed using equation (1) as follows:
Key Terms in this Chapter
Electroflotation: Is a process of floating of pollutants to water surface by tiny bubbles of hydrogen and oxygen gases generated from water electrolysis. Electroflotation module consists of electroflotator with insoluble electrodes, tanks for alkali and flocculant solutions, pumps, rectifier, sludge collecting system (Skimmer).
Electrochemical Treatment Technique: Any process either caused or accompanied by the passage of an electric current and involving in most cases the transfer of electrons between two substances—one a solid and the other a liquid
Electrodeposition: Is a process that uses an electric current to reduce dissolved metal cations so that they form a thin coherent metal coating on an electrode.
Emerging Pollutants (EPs): Synthetic or naturally occurring chemicals that are not commonly monitored in the environment, but which have the potential to enter the environment and cause known or suspected adverse ecological and (or) human health effects.
Electrocoagulation: Is a broad-spectrum treatment technology that removes total suspended solids (TSS), heavy metals, emulsified oils, bacteria and other contaminants from water (is a technique used for wash water treatment, wastewater treatment, industrial processed water, and medical treatment).
Electrophoretic Deposition: Is a term for a broad range of industrial processes which includes electrocoating, cathodic electrodeposition, anodic electrodeposition, and electrophoretic coating, or electrophoretic painting.
Chemical Oxygen Demand: Amount of oxygen required to oxidize both organic and inorganic substances in wastewaters.
Ozonation Treatment: Oxidation process that requires the use of ozone.