A Study On Treatment Of Furfural Wastewater With Iron Filings Filtering- Multistage Hydrolytic/Aerobic Processes

Furfural is an important chemical material, which is widely used in organic synthesis, remedy and pesticide processing. The principle of the furfural producing is that high-content poly-pentose corn-core as raw materials is heated at high temperature under the catalyst of dilute sulfuric acid or dilute hydrochloric, the poly-pentose hydrolyze and become pentose, then under the same catalytic condition, pentose dehydrate and become furfural. During the producing of the furfural, the there are 20 tons wastewater discharged when 1ton furfural produced. CODcr of this kind of wastewater is 8000-12000mg/l, pH is 2-3. In the wastewater, there is 2.0%-3.0% organic acid and adehyde. If this kind of wastewater is discharged directly without proper treatment, it will make the receiving water seriously polluted, so it has obvious economic and environment benefits to seek some feasible techniques to treat the furfural wastewater and improve the receiving water quality. Generally, both physico-chemical method and biochemical method are used in the furfural wastewater treatment just now. Physico-chemical method includes extraction-distillation process, catalytic-oxidation process, electro-dialysis and feton's process. The biochemical method includes anaerobic filter, anaerobic biological treatment, UASB reactor and fixed cultured-bacteria degradation. In this paper, "iron filings filtering -multi-stages hydrolytic/aerobic process"is used to treat furfural waste water. The objective of the research is to investigate the feasibilities of this process and its performance, then provide the design index for the engineering application. The principle of the iron filings in waste water treatment is that the iron filings constitute galvanic battery with carbon, the pollutant is removed because the chemical reactions take place on the cathode and sorption and flocculation of galvanic battery. The pretreatment of iron filings filter has been widely used in the dyeing wastewater, arsenical and fluorine wastewater, the oil industry wastewater, the galvanization wastewater treatment and so on. The hydrolysis/aerobic process is composed of the hydrolysis reactor and the oxygen reactor, which is not only used in the low pollution concentration city sewage treatment, but also used in the dye wastewater, the paper-making wastewater, the coked wastewater treatment and so on. Multi-stages hydrolysis/aerobic process has been efficiently used in the starch wastewater, gasification wastewater treatment, which provide the foundation of the study in furfural wastewater treatment. The iron filings filter -multistage hydrolytic/aerobic process is composed of two parts, one is pretreatment method, which includes the iron filings filtering, the alkalizing adjusts the pH value and the coagulation precipitating, and another is biochemical treatment methods, including hydrolysis/aerobic reactor and two contact oxidation reactors. After being filtered by the iron filings, the effluent CODcr of the multi-stages hydrolysis/ aerobic process is 138mg/l, when the influent CODcr reaches as high as 5745mg/l,which can achieve the Integrated Wastewater Discharge Standard (GB 8978-1996) level 2 (CODcr 150mg/l) In order to confirm the feasibility of the iron filings filter multi-stages hydrolysis/ aerobic process in furfural wastewater treatment, the process was applied to an actual engineering in Jilin province. The process can also get high performance in the practical engineering. In the condition of influent CODCr being 11346 mg/l, effluent CODcr is 129mg/l, which can achieve Integrated Wastewater Discharge Standard (GB 8978-1996) level 2(CODcr 150mg/l). Iron filings take very important parts in the process. After wastewater being pretreated by iron filings, CODcr reduces from average 9795mg/l to 8087mg/l, the removal efficiency is 17.4%.The wastewater pH rises from 2.56 to 3.73, the average furfural content in the wastewater drops from 0.075% to 0.017%, furfural removal efficiency is 77.3%. During the furfural wastewater treatment, the massive Fe2+ was produced...