Taiga HIRAOKA

Study on the Biological Treatment of Bioethanol Wastewater

Takashi YAMAGUCHI

The bioethanol has been attracting attention as a petroleum alternative fuel and a global warming countermeasure. The bioethanol has the advantages of carbon-neutral and renewable. However, the bioethanol has the disadvantage of massive amount of waste generation in production process. The waste has fermentation waste, distillery waste and washing wastewater. The characteristics of the wastewater include high-strength organic matter and nitrogen, and takes on blackish brown including pigment of low degradability such as melanoidin or caramel.
I focus attention on a combination of biological treatment that remove organic and membrane treatment that remove pigment as a treatment process of this wastewater. In this study, I suggest UASB (Upflow Anaerobic Sludge Bed)/ DHS (Downflow Hanging Sponge)/ ASB(Anaerobic Sludge Bed) as a biological treatment system. I comprehend organic removal capacity and nitrogen removal capacity and discussed the applicability to the washing wastewater treatment.
The experiment consists of three phases and changed temperature condition and substrate composition. In the first phase, the system consists of UASB with effective Vol. 15.1L, DHS with sponge Vol. 9.7L and AFB with effective Vol.5.0L and operated it in methophilic condition. The system was operated by feeding distillery wastewater. Its purpose was cultivation of sludge and comprehends the treatment characteristics. In the second phase, the system consists of 1stUASB with effective Vol. 15.1 L, 2ndUASB with effective Vol. 6.6 L, DHS with sponge Vol. 9.7 L and AFB with effective Vol.5.0 L and operated it in a room temperature condition. The system was operated by feeding molasses wastewater or distillery wastewater. Its purpose was treatment performance investigation of organic carbon, nitrogen and color. In the third phase, the system consists of 1stUASB with effective Vol. 20.6 L, 2ndUASB with effective Vol. 17.8L, DHS with sponge Vol. 4.7 L and ASB (Anaerobic Sludge Bed) with effective Vol.17.8 L and operated it in 25 degrees condition. The system was operated by feeding simulated washing wastewater made from mixed of molasses, fermentation waste with distillery waste and diluted. Its purpose was investigation of organic carbon and nitrogen treatment performance.
As the treatment characteristics, the result of the experiment has found that 1) the UASB/DHS/AFB system has high BOD removal performance for this wastewater. 2) the system cannot remove COD derived from pigment of low degradability. 3) UASB has decoloration performance for this wastewater, but the system cannot remove color to produce the coloration in DHS. As the treatment performance, the result of the experiment has found that 1) COD and BOD removal by the UASB/DHS/ASB system was 90.1% and 99.3% and the last treated water met effluent standard of BOD. 2) Total nitrogen removal by the system was 81.1%

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