| Furfural is an important furan-based platform compound,which can derive many high value-added chemical intermediates,which are widely used in pesticides,resins,pharmaceuticals,petroleum,chemical and aviation fuel alkanes and other fields.Furfural wastewater contains high organic matter concentration,strong acidity and high salinity,and its comprehensive treatment is relatively difficult.In this paper,the actual wastewater for the production of furfural was the object,and the anaerobic digestion enhanced by iron-carbon micro-electrolysis was the main research content,and the relevant design and operating parameters of the related process were obtained through batch tests and continuous tests.The research results have positive guiding significance for practical engineering applications,and have reference value for the treatment of similar types of wastewater.The main findings are as follows:1.The acidity of furfural wastewater is mainly caused by organic acids,and batch tests show that the anaerobic biodegradability of furfural wastewater after pH adjustment is good,reaching 93.25%,which is suitable for anaerobic biological treatment.Continuity tests showed that after 100 days of acclimation,the maximum volumetric load of reactor operation was 8.27 kg COD/（m3·d）,and the COD removal rate was stable at more than 88%.Kinetic analysis showed that the Grau secondary complex matrix degradation kinetic model was more suitable for simulating the matrix degradation process of furfural wastewater,b=0.9177,a=0.3273,ks=1.41 d-1,R2=0.9945.2.The pH and reflux ratio have a great influence on anaerobic biological treatment of furfural wastewater.When the influent pH is 6.8,the maximum influent COD that the reactor can operate normally is 19.5 g/L;When the influent pH is 5.05,the maximum influent COD is 13 g/L.This is due to the acid-base equilibrium system in the reactor,which together determine the pH in the reactor.Different reflux ratio tests show that when r>60,the reactor configuration is close to that of a fully mixed reactor.When 60>r>18,the reactor configuration is between push-flow type and complete mixing type,the influent COD load is 13.14 g/L,1.3 g/L is above,the removal rate is more than 90%,the gas production is 11 L/d,and the operation reactor is normal.When r<18,the reactor configuration was close to the push-flow type,there was a significant matrix concentration gradient in the reactor,the gas production gradually decreased from 11 L/d to 1 L/d,and the effluent COD also increased to 2.74g/L.The optimal reflux ratio is r=60,and the effluent COD is 0.62 g/L,which is slightly better than the effluent when r=120.For furfural wastewater with low pH and high load,a fully mixed reactor can adapt more effectively to volatile acidic shocks than a push-flow reactor.3.The effect of iron-carbon micro-electrolysis enhanced anaerobic biological treatment is obvious.The optimal conditions for iron-carbon microelectrolysis reaction were pH=3,COD=10 g/L,iron-carbon dosage of 900 g/500 m L,and the maximum removal rate of pollutants in batch test was 15.5%in 60 min reaction time.The long-term operation effect of iron-carbon microelectrolytic enhanced anaerobic biological process showed that the minimum pH of the influent was 4.46,COD=9.3g/L,the effluent pH=6.5,the effluent COD was below 0.6 g/L,and the removal rate was stable above 93%.The operation of furfural wastewater treated by iron-carbon micro-electrolysis enhanced anaerobic biological treatment was more stable,the sludge in the system showed better methanogenic performance,and the abundance of desulfurization bacteria Desulfobacterota and methanobacterium Methanobacterium increased significantly.Economic analysis shows that the operating cost of ordinary anaerobic digestion low pH is 8.78 yuan/t,and the operating cost of iron-carbon micro-electrolytic enhanced anaerobic digestion is 5.87～8.03 yuan/t,which can save8.54～33.1%compared with the cost,significantly save the cost of chemicals and increase the economic benefits of biogas power generation. |
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