Study On Extract Lactose From Whey By Crystallization And Membrane Filtration Process

The raw materials of the experiment is whey which is waste liquid of casein in production,the lactose recycling were studied by the method of crystallized and membrane filtration.Through the single factor and the orthogonal text,the major effect factor and the process parameter of the crystallization method were studied,the main technical process and the parameter of lactose product by crystallization has determined;the lactose's physics and chemistry target were determinate more overall by the national standard method;The membrane filtration method has determined the material and the structural style of the nanofiltration,the system's running technology was studied,and analysised the composition changes of permeate and concentrate liquid during the process of operation.The results are as follows:1.During the experiment which product lactose by crystallization method,take the whey which is waste liquid of casein in production as the raw material,we can get lactose after removal of whey protein and concentration crystallization.2.Through the single factor test,determined pH,soaking time and crystallization of concention as the main impact factors and then using L9(34)orthogonal test, take the recovery and the physical and chemical properties of lactose as the basis,screened out the best process parameter were:pH is 6.8,soaking time is 40 minute,and crystallization of concentration is 50Bx.3. Whey assumes the light yellow green, after the concentration the color can deepen, let the lactose assumes the transparent crystal shape, must carry on decolorization processing to the lactose concentrated liquid.By using L9(34)orthogonal test,take the decoloration rate of lactose as the basis, screened out the best process parameter of activated carbon decolorizing:activated carbon dosage 2%,heating temperature 80℃and adsorption time 30min.4.Follow the best process parameter above,we can recover 5.782g lactose every 250mL whey,means that the recovery of lactose which comes from whey by crystallize method can reach to 44.48%Lactose produced by crystallization has the lactose's unique sweet taste, no pasty and nasty smell,assumes the white crystalline state;The moisture content,the ash, the chloride,the lactose content respectively is:2.06%,1.32%,1.9%,92.8%, the lactose proceed by the experiment accords the national standard's requirements.5.Produce lactose membrane parting method,using the intermittent type operation in movement pressure1.0MPa,and the temperature under 50℃.The filtration time is 20 hours in each cycle,the biggest loading design is 1.6ton per hour;The biggest feeding liquid volume is 32M3;nanofiltration concentration multiple is 4;watering quantity of nanofiltration is 20% of the material fluid volume.The system's designed clean time is 90 to120 minutes each time,plus the top material's switching time,the plan is 4.0 hours.Clean one time each batch.6.After the whey treated by the nanofiltration membrane,94.44% of the lactose was intercepted in the concentration fluid, 86.51 % of the chloride was separated,the salt content in lactose was reduced. We can get the cream colored lactose powder after spray drying,the powder pellet is exquisite,has the sweet taste which the lactose uses especially,the sensory indexes accord to the GB requirements,the lactose content is 83.68.7.We can get 0.051 Kg powdered lactose per 1 Kg whey after spray drying,means that 51Kg powdered lactose can be produced every ton whey;if 30t whey can produced one day,1530kg powdered lactose can be produced everyday.Lactose content is 5.85% in whey,and then we can get 1755 Kg lactose in 30t whey,by using the nanofiltration membrane technology the recovery rate of lactose can reach to 87.18%.In summary,uses the membrane method to recycle the lactose which comes from whey,the operation is simple but the purity is low;and the crystallization method's is the lactose's purity is high but the recovery rate is low,moreover the operation process is complex. Therefore,in the practical production process,we should use the membrane filtration method to extracte primarily,and then use the crystallization method to purified the lactose,to improve the lactose content in the product,improve the economic efficiency of the enterprise.