Study On Preparation Of Bioflocculant By Using Excess Sludge From Meat Processing Plant

With the continuous improvement of people's living standards,the market demand of meat products has increased,correspondingly,the production scale of the meat products has been enlarged,as the result the amount of sewage treatment and sludge production has increased in the meantime.The sludge,as a certain by-product of sewage treatment processes,contains a variety of organic matters,and the macromolecular organics within them possess the function of flocculation.As a result,the macromolecular organics within the sludge possess the ability to improve the biodegradability of wastewater and reduce the turbidity and the chroma of wastewater.By these ways it can provide a better nutritional condition for biological treatment,and improve the treatment efficiency eventually.In this research,the alkali-thermal treatment was used for the release of intracellular substances by cracking the cell wall,the best condition of the sludge cracking treatment has been selected,and the continuous operational sludge cracking device was designed as well.For the bio-flocculant prepared by this experiment,the basic characteristics analysis and the active component of flocculation analysis had been carried out.To test the efficiency of the sample produced under the best condition,three simulated wastewater samples were used to perform flocculation experiments,by which the best flocculation condition and the flocculation efficiency were analyzed.The physical and chemical characteristics of excess sludge collected from the secondary sedimentation tank of a meat processing plant in Dalian,Liaoning Province were determined.The results showed that the total chemical oxygen demand(TCOD),soluble chemical oxygen demand(SCOD),soluble carbohydrate(SC)and soluble protein(SP)were 12768 mg/L,260.83 mg/L,27.43 mg/L and 6.71 mg/L,respectively.Zinc,nickel and copper were detected in the samples,with a content of 0.2773 mg/L,0.0702 mg/L and 0.0817 mg/L,respectively.In order to investigate the best experimental conditions for the hydrolysis of sludge with the alkali-thermal treatment,a single-factor experiment was performed.It was found that the best effect was achieved with a COD dissolution rate of 73.10% under the conditions of pH=14,reaction temperature of 30°C,and reaction time of 12 h.The bioflocculant sample was obtained from the supernatant of the resultant after centrifugation.The analysis of the prepared biological flocculant sample showed that the content of SCOD,SP and SC were 9302.4 mg/L,1576.45 mg/L and 808.74 mg/L,respectively.In addition,the flocculant has good thermal stability.After heating in 100°C water bath for 30 min,the flocculation rate of kaolin suspension was only 13.72% lower than that of the control group without heating.The active substances of the flocculant were extracted,concentrated,dried and then analyzed by infrared spectrum.The information on characteristic absorption peaks in the spectrum showed that the main active substances of the flocculants were carbohydrates.In order to investigate the flocculating performance of the bioflocculant sample,flocculation experiments were performed on Kaolin suspension,simulated Congo red dye effluent and simulated phenol-kaolin coking effluent.The results showed that the resultant,as a bioflocculant,had a remarkable effect on effluent disposal,with a flocculation rate of 98.39% for Kaolin suspension,90.48% for simulated Congo red dye effluent,and a COD removal rate of 9.80% for simulated phenol-kaolin coking effluent.