New area for distillation: wastewater treatment

Abstract

The protection of our environment is an actual and global problem in our time and the wastewater treatment is its important part. It is based on biological treatment. In certain cases, however, due to special regulations, the biological tools are not allowed and other options should be considered and selected. The incineration is an alternative but impact assessment studies show that it can make a serious burden upon the environment as well as it might be an expensive solution. Physico-chemical tools can mean a realistic alternative in such cases. In case of wastewater containing organic solvents (ethanol, ethyl-acetate, toluene, halogenated solvents, etc.), that is typical for wastewaters of medicine and fine chemical industries, the distillation is a powerful tool to remove the volatile polluting compounds. These volatile organic compounds (VOC) can contribute significantly to the chemical oxygen demand (COD) of the wastewater. This contribution we call VOC-COD. The Adsorbable Organically Bound Halogens (AOX) can be removed also with distillation. Industrial case studies show that the distillation offers a realistic alternative and the recovered solvents can be also utilised. The COD can be reduced in certain cases below the emission limit (1000 mg/lit) and the AOX, after the physico-chemical treatment, is less than 8 mg/lit.

Comparison of pervaporation models with simulation of hybrid separation processes

“…crude oil processing, process wastewater treatment, etc. ); however it has a great energy demand as a huge drawback in an environmental point of view [19][20]. In case of alcohol dehydration, pervaporation is more efficient in that range of feed concentration where distillation is very inefficient, while at higher feed water concentrations distillation is the more reasonable choice.…”

Comparison of air and steam stripping: removal of organic halogen compounds from process wastewaters

“…This is the reason why the AOX removal is so important, and our industrial case study focuses on the removal of AOX compounds with stripping. Of course, if stripping is applied, the VOC content is also reduced (Koczka and Mizsey 2010), but in this research, this is out of scope and we just focus on the AOX removal in agreement with the industrial procedure.…”

Physicochemical treatment of pharmaceutical process wastewater: distillation and membrane processes

“…A number of physicochemical methods are suitable for treating process wastewater, which primarily remove the organic solvents and reduce the chemical oxygen demand [11]. The selection of these methods depend on many factors, such as:…”

“…Hereafter, applicability, advantages and disadvantages of the main physicochemical methods are described. The main physicochemical methods are: absorption [12], adsorption [12], ion exchange [12], extraction [12], evaporation [11], wet oxidation [13], distillation and membrane processes.…”