Pretreatment Of Wastewater With High Concentration Of Formaldehyde By Recycling Of Ammonia

In this paper, composite process composed of condensation-activated carbon adsorption was researched experimentally for pretreatment of high-level formaldehyde wastewater. The influencing factors were investigated. The composite process was optimized through response surface method based on single factor test and analysis by response surface method obtained the optimum technological. The scale-up experimentation of the wastewater treatment was processed based on the data of lab trials. Based on lab tests, through technical and economic argumentation, the technique has been proposed to treat formaldehyde wastewater with high concentration by combining condensation and activated carbon adsorption. The design of the wastewater treatment process has the characteristics of operate easily, simple and efficient can realize organic compound reduction, recycling of ammonia, low cost and so on and has potentially real application. The main research conclusions are as follows:The research in the laboratory obtained the optimized process conditions of condensation and activated carbon adsorption was researched experimentally for pretreatment of high-level formaldehyde wastewater. The optimized process conditions of condensation was researched experimentally for pretreatment of high-level formaldehyde wastewater:the best reaction time was 5 h, the best reaction temperature was 31.4℃,the best oscillation frequency was 139.5 r/min, the best ammonia concentration was 3.54%,the ratio of liquid to materials 1:6.The removal efficiency of formaldehyde was reached 86.383%,under above conditions. The optimized process conditions of activated carbon adsorption was researched experimentally for pretreatment of high-level formaldehyde wastewater:the results of the static adsorption experiment showed that the best dosage of activated carbon was 7.736 g, the best absorption time 5 h, the best absorption temperature was 27 "C.The removal efficiency of formaldehyde was reached 98.85%,under above conditions. The results of the dynamic adsorption experiment showed that the best treatment capacity of activated carbon was 16.67 mL/g and the velocity of flow was 8 mL/min.The optimal technological scale-up process validation test, the conclusion can be drawn:the method of the small test can also be applied into the scale-up test.Process route was designed under optimum conditions which were determined on the basis of laboratory. According to the design of the process flow diagram and piping & instrument diagram, got the results of energy balance and mass balance.Based on the experimental results and the evaluation of the technical, it can be found that the combining technical of condensation-activated carbon adsorption can achieve the purposes of economical and efficient for the treatment of high concentrations of formaldehyde wastewater.