Research On The Advanced Treatment Of DMAC Wastewater Produced From Hollow Fiber Membrane

Dimethyl acetamide(DMAC) was an important reaction solvent for producing hollowfiber membrane,so it will produce DMAC wastewater which was of high COD, hightoxicity,and was soluble with water at free percentage generates in the production process.The direct discharge of the wastewater can cause serious environmental pollution. The objectof this research was0.5%DMAC wastewater (COD was about3200mg/L), and thefeasibility and process conditions of wastewater treatment to deal with this type of wastewaterwere studied in this topic.This study adopted the Fenton oxidation method to deal with0.5%DMACwastewater.When under the optimum condition:0.25mol/L H2O2,12.5mmol/L FeSO4·7H2O,pH was3.0, reaction time was1hour, and H2O2using quadratic dosing, the COD removalrate was about51%,and the COD of effluent wastewater was about1600mg/L,which was stillfar from the industrial wastewater emission standard. Then static adsorption of activatedcarbon method was used to treat the wastewater unable to discharge(COD was about1600mg/L). Combing the laboratory experiment with the practical engineering applicationand economic feasibility analysis, we obtained the following optimum condition: the dosageof activated carbon was40g/L, Operating temperature was25℃, reaction time was2hour, pHwas7.Under the optimum condition,COD of effluent wastewater was235mg/L, the CODremoval rate was85.3%,and the adsorption isotherm accorded with the Freundlich equation,and adsorption kinetics curve entirely fitted the pseudo secondary adsorption dynamicsequation. Two-level dynamic adsorption of activated carbon was used to treat DMACwastewater of which COD was1600mg/L and the flow rate of influent was5mL/min.Afterthe two tandem level adsorption column, the COD of effluent wastewater was reduced to86.7mg/L. By determining the breakthrough curve of active carbon adsorption column, we knew that the absorption capacity of activated carbon was60-80L wastewater perkilograms.Activated sludge method was studied to treat the wastewater and both the sludgeand the microbial community grew well under the condition that the temperature was25℃,pH was7, DO was2-3mg/L,and aeration time was8h every day. By adding the proportion ofexperiments, we concluded that when the quantity of DMAC wastewater was8.0%(volumefraction), the COD of effluent wastewater was106.7-156.2mg/L, the treatment capacity ofdomestication sludge reached its limit. Therefore the highest dosing of DMAC wastewatershould be8.0%.Overall consideration of the treatment effect, processing costs and other aspects ofdifferent methods treating DMAC wastewater suggested that using the activated sludgemethod could not only reach the final emission standard,but also reduce the investmentoperation cost.Therefore, in practical engineering, when the quantity of DMAC wastewater issmall, the DMAC wastewater with initial concentration of3200mg/L can be transported to thenear sewage treatment plant where it is mixed with urban sewage according to the proportionof8:100,and then they are treated together by activated sludge method.