Study On The Treatment Process Of The High-concentration Part Of Caramel Pigment Wastewater

Caramel pigment wastewater is a kind typical high-concentration organic industrial wastewater which produced from the caramel pigment production processes and characterized by intensive color and high chemical oxygen demand(COD).This study involves the high concentration caramel pigment wastewater treatment,including the analysis of caramel wastewater,the research of wastewater treatment technology,the optimization of process parameters for the treatment technology,the analysis of wastewater which treated by ultrasound-Fenton(US-Fenton)process.A series of results are followed through the experiments and analysis:(1)The result of basic examination of wastewater,IR,UV-Vis,NMR,GC-MS and LC-MS indicated that:The caramel pigment wastewater is a kind high concentration organic wastewater characterized by intensive color,high COD and bio-refractory;the wastewater contains many unsaturated chemical bonds,conjugated groups and some groups characterized by high electron density;these groups were rich and had complex chemical structures,including ring structure and long chain structure,resulting in the intensive color and high COD property of caramel wastewater.(2)A technology treating the caramel wastewater was designed and studied according to the property of caramel wastewater and the characteristic of industry wastewater produced from the caramel pigment production processes.The technology included a simple pretreatment process of wastewater with coagulation-flocculation,an ultrasound-Fenton(US-Fenton)treatment process and an sequencing batch reactor activated sludge(SBR)process.The wastewater color and COD changed from approximately 270,000 Hazen unit,90,OOOmg/L respectively to 200 Hazen unit,300mg/L respectively after the technology was used to treat the caramel wastewater.(3)In the the coagulation-flocculation section,the high concentration caramel wastewater got a result that wastewater color removal and wastewater COD removal efficiency reached 83.3%and 44.3%with the final color and COD were 4300 Hazen unit and 5000mg/L under the optimum conditions.(4)In ultrasonic-Fenton section,the coagulation-flocculation treated caramel wastewater was oxided by ultrasound-Fenton,the wastewater final color and COD were 400 Hazen unit and 1500mg/L under the optimum conditions,color and COD removal efficiency reached 87.6%and 79.9%within 5min with which the process achieved maximum treatment effect.(5)The comparison information of IR and UV-Vis indicated that:the IR absorbance peaks and the corresponding functional groups have changed or disappeared when the caramel wastewater went through the US-Fenton process;while the UV-vis results showed that the UV-Vis absorbance peak height at 276nm gradually decrease until a constant during the US-Fenton process,and there was no other UV-Vis absorbance peak coming about during the US-Fenton process.(6)The comparison information of GC-MS and LC-MS indicated that:The wastewater composition has changed after the US-Fenton process.The main material 9-Octadecenamide disappeared completely after a US-Fenton process.(7)A SBR activated sludge treatment system which could handle ultrasound-Fenton treated wastewater were cultured.The SBR treatment system could worked under load of the influent COD of 1500 mg/L,the processing period of 6h.The effluent wastewater COD and color from the SBR system were 300mg/L and 200 Hazen unit.