Purification of Industrial Waste Water Applying Thermal Methods and Comparison with Biological Treatment

Abstract

AbstractIndustrial effluents can still respond to biological treatment if they contain high proportions of organic matter, provided that they can be mixed with other effluents that have a lower pollutant load so that the maximum permissible organic carbon in the entire water treatment plant is not exceeded. However integrated treatment consisting of a prior physical stage followed by a biological stage may be cheaper than biological treatment alone. The results depend on the nature and concentration of pollutants. In fact, purely physical treatment may even be the most economic of all for many effluents polluted by organic matter. In many cases, physical methods may be an absolute necessity. For instance, the pollutants may not be completely biodegradable and may not respond to chemical pretreatment. Alternatively, the effluent to be treated may contain valuable substances whose recovery is essential for the economics of the process concerned. Important physical methods for realizing this aim include thermal processes, e. g. evaporation, crystallization, distillation, rectification and extraction. They may be applied singly or combined. Obviously, these methods may also be resorted to for recovering substances formerly regarded as waste. If a significant improvement is to be achieved in the ecological situation and if industrial production capacity expands according to expectation, these substances may well be regarded in future as resources, and their recovery may become imperative.