The Study On Biodegradation Of Industrial Formaldehyde Wastewater Using Sequencing Batch Reactor Processing

In this dissertation, the biodegradability of industrial formaldehyde wastewater discharged from one chemical company was studied. The research mainly focused on the biodegradability of industrial formaldehyde wastewater in anaerobic sequencing batch reactor (ASBR), the biodegradability in aerobic sequencing batch reactor (SBR), and the biodegradation using ASBR combined with SBR. The following conclusion was drawed from the research:(1) After ASBR was started up with low sludge load, the removal rate of CODcr was75%and the removal rate of formaldehyde could reach98%. When sluge load increased, the removal rate of CODcr decreased while the removal rate of formaldehyde stayed stable. The optimal conditions of ASBR should be pH7.2and HRT18hours.(2) After SBR was started up within10days, activated sludge could adapt to the toxicity of industrial formaldehyde wastewater and maintain the removal rate of CODcr when the sludge load increased. It was found that the biodegradability of industrial formaldehyde wastewater could be stable when sludge load was221.8mg/(L·d、277.3mg/(L·d)、332.7mg/(L·d) but the biodegradability became worse with the times of experiments increasing when sludge load was443.6mg/(L·d) and554.5mg/(L·d). The aerobic biodegradation of CODCr and formaldehyde was a zero order reaction when the influent volume was6mL or9mL.When sludge load was332.7mg/(L·d) and temperature was changed from15℃to35℃, the removal rate of CODCr did not changed too much(Q10=1.05), but the removal rate of formaldehyde was changed more(Q10=1.37).(3) Combined ASBR and SBR, under the optimal conditions of ASBR sludge load554.5mg/(L·d), pH7.2, HRT18hours and SBR HRT5hours, pH7.2, amount of aeration0.35L/min, the concentration of CODCr in the effluent could reach below60mg/L, the removal rate of CODcr was92%, and the concentration of formaldehyde below1mg/L, the removal rate of formaldehyde99.7%.(4) It was found that the nonbiodegradable materials in the industrial formaldehyde wastewater mainly were formaldehyde, chloroform and n-dedocyl aldehyde by using Purge&Trap-GC-MS testing the influent and the effluent of different reaction time.