The Study On Conversion Of Formaldehyde And Crotonaldehyde By Hydrolytic Acidification With Sodium Dodecyl Sulfate

The aldehyde wastewater is a typical toxic organic wastewater that is difficult to degrade.If wastewater had not been treated and discharged into a biological treatment unit,the toxic organic matter in wastewater will impact the biological treatment unit,affecting the effect of biological treatment.Hydrolytic acidification is a common treatment process,which has a certain detoxification effect on aldehydes.Studies show that sodium dodecyl sulfate(SDS)can promote hydrolytic acidification.In this study,the influence of substrate concentration,sludge concentration and pH on hydrolytic acidification of wastewater containing formaldehyde or crotonaldehyde were investigated.Under optimal hydrolytic acidification conditions,the single aldehyde system,the mixed aldehyde system and the system containing SDS were set.The effects of mixed aldehydes and SDS on the performance of hydrolytic acidification were revealed,by comparing the variations of degradation of crotonaldehyde and formaldehyde,acid-production,butyrate kinase content,microbial diversity,extracellular polymeric substance(EPS),soluble microbial products(SMP).Results:1.The optimum conditions of hydrolytic acidification toxicity experiments were food/microor-ganism(F/M)of 1.47-2.21,sludge concentration at 2.42-4.84 g/L and pH among 7-9.2.In the single formaldehyde system,low concentration of formaldehyde can promote acid-production,but high concentration of formaldehyde can inhibit acid-production.In the single crotonaldehyde system,acid-production was inhibited.The addition of formaldehyde and crotonaldehyde promoted the secretion of EPS and SMP.3.SDS was added to mixed aldehyde systems.The results shown that SDS promoted the secretion of butyrate kinase,the production of acid,the degradation of formaldehyde and crotonaldehyde,the secretion of EPS and SMP,the resistance to toxic substances,and microbial activity.4.The addition of SDS increased the abundance of hydrolytic acidification bacteria,thus promoting hydrolytic acidification.With the increase of aldehyde concentration,the microbial diversity decreased and some microorganisms were inhibited,while Firmicutes and Bacteroidota that resistant to harsh environment were promoted.Firmicutes and Bacteroidota contained a large number of hydrolytic acidifying bacteria,which promoted the hydrolysis acidification.Compared with single aldehyde,the mixed aldehyde system promoted hydrolytic acidification due to the growth of hydrolytic acidification Firmicutes bacteria resistant to harsh environment promoted.