Study On Comprehensive Utilization Of Soybean Whey

Soybean whey was drained in the processes of soybean isolation protein, which wasproduced by alkali dissolution and acid sediment method. In whey total soluble solid wasabout3.1%, protein was about0.9%, total sugar was about1.2%; BOD5value was about8600mg/L, COD value was about17000mg/L. Most of whey was directly discharged, whichcaused resource waste and environment pollution seriously. Up to now, the wastewaterhanding problem was not resolved well. In order to recycle the wastewater, this paper studiedthe application of membranes in the treatment of soybean whey and the reclaimation ofsoybean whey protein and oligosaccharides, and water cycle.In the first place, in order to wipe off phytic acid, single factor experiment wasconducted to determine the optimal pretreatment conditions: pH9.0, time15min, temperature45-50℃.and it was centrifuged to supernate.The performance and operating conditions of UF using polyether sulfone UF-10membrane was investigated for treating soybean whey.The results showed that the optimalconditions of ultrafiltration concentrated soybean whey protein were concentation ratio5,pH4.5，pressure0.05MPa, temperature45℃. And under this condition, the contents ofsoybean whey protein in ultra-filtration concentrate was34.76g/L.the BOD5and COD fall to5700mg/L and14000mg/L, respectively; protein rejection coefficient was about80%, totalsugar permeate coefficient was also about80%, which achieved the separation of protein andsugar basically.The optimal decoloration by active carbon conditions of ultrafiltration permeate wasdetermined by orthogonal experiment: pH3.9, amount of powder active carbon1.1%,temperature53℃, time20min. Under this condition, the decoloration ratio was84.12%. andafter that, The results showed that the optimal conditions of were concentation ratio10,pressure0.6MPa, temperature45℃. And under this condition, the contents of soybeanoligosaccharides was33.67g/L. the BOD5and COD fall to55mg/L and150mg/L,respectively. At last, the nanofiltration permeate was treated by reverse osmosis, inorganicsalt and monosaccharide was wiped off and cycle water. The production engineering of comprehensive utilization of soybean whey: soy wheyprotein powder was achieved by soybean whey which pretreated passing through someprocess (ultrafiltration, dual-purpose evaporation, spray drying). soybean oligosaccharidespowder was also achieved by ultrafiltration permeate passing though some process(nanofiltration, dual-purpose evaporation, spray drying) nanofiltration permeate wasretreated by reverse osmosis, which can get reclaimed wastewater.