| The types of industrial wastewater are as numerous as the types of industries. As a result, it is impossible to apply a comprehensive method of treatment. Many industries are in need of process modifications in order to comply with the constant changes in regulations of aqueous waste discharge into open water and sewage systems.The contamination of our environment by industrial waste has been known for some time however, little or no attention has been given to the printing industry, in particular the currency printing industry, which uses significant quantities of surfactants and dyes as well as generating highly alkaline wastewater. The purpose of this research was to provide a thorough study of the aqueous process streams at the British - American Banknote Inc. (BA Banknote Inc. a local currency printing industry), to identify locations for process optimization and to develop possible improvements.The design of the existing ultrafiltration unit at BA Banknote Inc. is not capable of performing at optimum capacity to recycle the highly alkaline wastewater. In order for the ultrafiltration unit to perform at an optimum condition, the solution passing through should be at a pH of 10. However, the subsequent flocculation step in the process will only be at an optimum condition when the solution passing through is at a pH of 12. The most common method of pH adjustment is the use of strong acids and bases, but these lead to a build-up of salts in the system. Hence, development of a temporary pH adjustment process using CO2 gas to reduce the pH prior to the ultrafiltration unit and N2 gas to raise the pH afterwards was attempted. This involved development of a computer model which can predict the concentration of the carbonated species, the rate constants for the reaction CO2 (g) &hArr CO2 (aq), and the rate of pH change (concentration of H + ion) as a function of temperature. The determined rate constants provided the apparent activation energy of -47 kJ/mol and -27 kJ/mol for the forward and reverse reactions respectively, of dissolution of CO2 in water. Subsequently, mass transfer calculations were performed in order to assess the validity of the model assumed in obtaining the numerical data. Results indicate reasonable agreement between the fluxes of CO2 entering the water and those found from mass transfer calculations.In the past few years, concern has increased about chemicals (surfactants, dyes, pesticides, etc) in the environment which have effects on the reproductive systems. Reports indicate that the majority of these industrial pollutants have a rather poor biodegradability and are capable of oestrogenic activity on various forms of life. Moreover, in certain water chlorination/disinfection steps, these chemicals can result in the formation of potentially carcinogenic compounds.Another objective of this study was thus to develop an analytical method for fast and efficient routine analysis of the process streams for the purpose of quality control and environmental monitoring. An analytical method using Capillary Electrophoresis (CE) has been developed which is capable of fast (under 8 minutes) analysis of the surfactant Turkey Red Oil at any stage of the process Gas chromatography-Mass Spectrometry (GC-MS) methods normally require an analysis time of 3 hours or more. However, the sensitivity of the developed method is not satisfactory enough to monitor the level of surfactants in the effluent streams entering the environment. |
