Investigation into the biological removal of sulphate from ethanol distillery wastewater using sulphate-reducing prokaryotes
- Authors: Smuts, Lizl
- Date: 2005
- Subjects: Sewage -- Purification -- Biological treatment , Prokaryotes , Sulfates , Distilleries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3941 , http://hdl.handle.net/10962/d1004000 , Sewage -- Purification -- Biological treatment , Prokaryotes , Sulfates , Distilleries -- Waste disposal
- Description: Ethanol production wastewater is known to be toxic, and is not easily biodegradable. It also consists of a variety of coloured components adding to the complex composition of this wastewater. Disposal of this wastewater into water courses is not recommended and yet is performed all over the world. Investigation of this wastewater found that there was a high concentration of sulphate which, in the presence of sulphate-reducing prokaryotes can cause sulphide corrosion of cement. The concentration of sulphate in the wastewater was approximately 2770 mg/L. It was also found that the wastewater pH was very low and discharge of the wastewater into the wastewater treatment works caused a negative impact on the overall quality of the final wastewater discharged to sea. It was found using FISH techniques that there were no sulphate-reducing prokaryotes present in the wastewaters but that a sulphate-reducing population existed on the sewer wall. An anaerobic contact process was designed to treat this wastewater targeting sulphate reduction to sulphide, to be converted into elemental sulphur and to increase the wastewater pH. The process did not achieve this aim and only approximately 20-30 % reduction in sulphate from the wastewater was achieved with little to no change in the pH. A 95 % reduction in sulphate concentration was needed in order to reach acceptable discharge limits. Sulphate reduction could not be carried out, even under ideal laboratory conditions. It was found that the barrier causing the digester failure was the high concentration of phenols present in the wastewater (3.3 g/L) together with the production of high concentrations of volatile fatty acids (on average 13 g acetic/L). These two components are known to cause digester failure, especially phenols, and phenols are usually only degraded by fungal species. It was concluded that the wastewater itself was not amenable to this method of biological treatment.
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- Date Issued: 2005
The development of the emerging technologies sustainability assessment (ETSA) and its application in the design of a bioprocess for the treatment of wine distillery effluent
- Authors: Khan, Nuraan
- Date: 2005
- Subjects: Technology assessment , Wine and wine making -- Waste disposal , Distilleries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3953 , http://hdl.handle.net/10962/d1004012 , Technology assessment , Wine and wine making -- Waste disposal , Distilleries -- Waste disposal
- Description: Emerging Technologies Sustainability Assessment (ETSA) is a new technology assessment tool that was developed in order to compare emerging processes or technologies to existing alternatives. It utilizes infoIDlation modules, with the minimum use of resources such as time and money, in order to deteIDline if the process under development is comparatively favourable and should be developed beyond the early conceptual phase. The preliminary ETSA is vital in order to identify the gaps in the existing information and the specific methodologies to be used for data capture and analysis. The use of experimental design tools, such as Design-Expert, can facilitate rapid and efficient collection of necessary data and fits in well with the rationale for the ETSA. Wine distillery effluent (vinasse) is the residue left after alcohol has been distilled from fennented grape juice. It is an acidic, darkly coloured effluent, with a high COD and polyphenol content. The most popular method of disposal of this effluent, land application, is no longer viable due to stricter legislation and pressure on the industry to better manage its wastes. Although the ability of whiterot fungi to degrade a number of pollutants is well-known, fungal treatment of wine distillery effluent is still in the conceptual phase. The perfoIDlance of the fungal remediation system was assessed experimentally in terms of COD removal and laccase production using Design-Expert. Although Pycnoporus sanguine us was found to be most efficient at COD removal (85%) from 30% vinasse, laccase production was low (0.021 U/I). The optimum design for economically viable fungal treatment used Trametespubescens. This fungus was able to remove over 50% of the COD from undiluted vinasse while producing almost 800U/l of the valuable laccase enzyme within three days. Since the effluent from the fungal system did not meet the legal limits for wastewater disposal, a two-stage aerobicanaerobic system is suggested to improve the quality of the effluent prior to disposal. The ETSA was used to assess the fungal technology in relation to the two current methods of vinasse treatment and disposal, namely land application and anaerobic digestion. Based on the ETSA, which considered environmental, social and economic impacts, the fungal system proved to be potentially competitive and further development of the technology is suggested.
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- Date Issued: 2005