Study On Pretreatment Of Organic Wastewater Containing Salts And Preliminary Design Of Technology

Dyestuff industry develops rapidly in our country, whose products were mainly used in textile, woodwork, leather, food, paint, etc. The Dyestuff industy is a manufacture with wide varieties and complex processes, and the wastewater contains a lot of organics and salts, which is of big chroma, high CODCr, high toxicity and difficult to be biodegraded. Nowadays, the dyes wastewater treatment is still a big problem in our country, so the wastewater treatment research has important practical value.This paper focuses on the treatment of wastewater with high salt and nitrogenous organic compound, which was discharged by a cationic dyes chemical plant Combining with the conditions of the cationic dyes chemical plant, the discharge condition of wastewater, the method of dye technology and the existing wastewater treatment system were investigated. In view of the methyl alcohol, nitrogenous organic compound and salt contained in the wastewater, we proposed an treatment scheme that combine physico-chemical treatment with biologic-chemical treatment.We adopt continuous side distillation tower and liquid-liquid extraction tower to separate the cationic dyes wastewater. The wasterwater will be discharged into the biologic-chemical treatment system after the pretreatment.The continuous side distillation was simulated by Aspen plus, and the conditions of simulation such as the plate number, feed location, top product quantity, side product quantity and reflux ratio were studied. The experimental apparatus of continuous side distillation was established, and experimental study was carried out on the basis of theoretical simulation data. The experimental results showed that the content of methanol at the top is 98.72% and the CODCr of side output is 2000ppm, under the conditions of that tower height was 1800mm, input height was 1300mm, onput height was 160mm, feeding speed was 5g/min, top distillation flow rate was 0.4g/min, side distillation flow rate was 3.6g/min, and reflux ratio was 5.5.The aqueous solution contains salt and nitrogenous organic compound from the bottom of the continuous side distillation was separated by liquid-liquid extraction to remove the nitrogenous organic compound, and the CODCr of evaporated liquor was 1280mg/L. The basis for model process package designing was provided by the simulation and experiment results. By the preliminary experiment research, the relevant parameter was gained to draw the process flow diagram and layout drawing, determine the main equipment table, control instrument table and complete the design of the craft bag.The craft bag mainly included design basis, process instructions, process operating conditions, material balance, process flow diagram, main equipment and control instruments, etc.Through laboratory test and wastewater treatment system filed research, proposed the cationic dye wastewater treatment process and method, using continuous side distillation sepration+liquid-liquid extraction+hydrolysis acidification+biological contact oxidation+ biological carbon filter, to ensure that the sewage treatment discharge standard was reached.