Anaerobic-SBR Treatment Of Soybean Oil Refinery Wastewater And Acetic Acid Recovery

Soybean oil refining wastewater has classic characteristics of huge quantity, high organic concentrations and easy to be degraded.Treating in traditional ways may waste a large number of potential energy. This paper takes wastewater from a soybean oil processing plant as study object, adopting pretreatment + anaerobic+ sequencing batch reactor SBR to treat wastewater, explore the effect of the entire process and the feasibility of acetic acid generation.Pretreatment with adding the acid, to make the oil and impurities in the water to aggregate, the mainly removed particle size from wastewater is 10-100 μm. This portion of particles gather more material and rise out of the water. By removing this part of the material, oil in waste water can be removed more than 77%, and COD can be removed more than 44%. Then the waste water will flow into the intermittent flow operation of high temperature anaerobic digestion, and the effect of different organic loading on removal efficiency was investigated. After anaerobic difestion COD removal rate is up to 79%.Volatile organic acids test showed that mainly volatile acid in anaerobic reactor water is acetic acid. Portion of propionic acid was detected. Concentrations of ther volatile organic acids are low. In high temperature anaerobic digestion, at first, most of macromolecular organic matter in waste water is converted into acetic acid, a small fraction is converted to propionic acid and other volatile organic acids, then utilized by anaerobic bacteria. The maximum of gas production is 18 m L for each cycle. Microbial community analysis in genus level shows that predominant bacteria in those 4 reactor is Dechloromonas Treponema Sporanaerobacter Desulfosporomusa Caloramator Desulfovibrio.COD can fully up to standard after treatment in SBR. After processing, chemical oxygen demand(CODs) can drop below 500 mg/L after treatment. Volatile organic acids test shows in waste water acetic acid is dominant, and maximum concentration is about220 mg/L, which is suitable for the recycling of acetic acid in the later stage. Acetic acid recycled wastewater can reach the plant’s water quality standards( CJ343-2010 wastewater quality standards for discharge to municipal sewers).The comparison between BES-SBR and SBR reactor shows that COD removal of BES-SBR is fast and better than that of SBR, but bioelectrochemistry has negative effects for acetic acid accumulation. High throughput sequencing test showed more exoelectrogens are found in BES-SBR than in SBR, which indicates that microorganisms can electron transfer extracellular should be responsible for a lower acetic acid accumulation BES-SBR than SBR, because most of exoelectrogens use acetic acid as substrate.