Variations In Molasses Wastewater Oxidatied By Hydrogen Peroxide

Oxidation treatment has been employed to treat molasses alcohol wastewater (MAWW). However, the effect of hydrogen peroxide oxidation under alkaline conditions and ivariations of system in the oxidation process need to be investigated. In this paper, hydrogen peroxide was employed to treat the MAWW which was pretreated by CaO. The components'variation of wastewater was observed in the oxidation process. The main contents and results are as follows:1.Determination of Molecular Weight (MW) of MAWW using the gel permeation chromatography. The result showed that MW of the pretreated MAWW was 18,000 ~ 38,000 and the distribution of organic matter were over this range. The oxidation conditions were determined by the MW and its distribution: without adjusting pH value of the CaO-pretreated MAWW, the reaction temperature was 15℃, the hydrogen peroxide dosage was 4 % (V/V) and the reaction time was setted at 12 h. The MW of oxidized MAWW was 16,000 ~ 35,000. The MW and its distribution were less affected by the change of oxidation conditions, which have effects on the content of organic pollutants. It confirmed that hydrogen peroxide decomposed chemical bonds of organic matter and removed pollutant under alkaline condition.2. Change of chemical oxygen demand (COD) of wastewater sample. The COD value increased firstly and then decreased as the dosage of H2O2 increased. The change of temperature has little impact on the COD value of wastewater over the range of 15～35℃. The initial pH has great impact on COD value,which was higer within pH=4～10, middle within pH=11～12 and lowest at pH=12.69. The results show that hydrogen peroxide oxidation has capacity to remove COD of wastewater under alkaline conditions, but less effective, so the use of oxidative degradation of COD alone is not feasible.3. Spectral scanning of wastewater samples in the visible—near-UV region and investigation of the colourity changes of wastewater sample, A560nm and A273nm value as an indetactor. 560 nm was the center of color intensity and 273 nm was UV absorbance peak of wastewater sample. The peak position and height of absorption curve and A560nm and A273nm values of the wastewater samples oxidated by hydrogen peroxide were changed but the 273nm absorption peak remained.4. Change of Tatol Nitrogen (TN) and Amino Nitrogen oncentration of wastewater samples. TN and Amino Nitrogen concentration of wastewater samples were decreased as the dosage of hydrogen peroxide increased, but the change of Amino Nitrogen concentration was little, which was likely resulted from -NH2 and NH3 in dynamic equilibrium under alkaline condition. Therefore, it was hardly to determine the contribution of hydrogen peroxide oxidation on Ammonia Nitrogen removal. The temperature has little effect on TN and Amino Nitrogen concentration. TN concentration has a little change within pH=4~6, increased in pH = 7 and decreased within pH = 8 ~ 12.69. With the change in pH value, slight fluctuation was found on the Ammonia Nitrogen curve, but the change of their value was very small.