Study On Improving Performances Of Sludge Protein Foaming Solution By ⁶0Coγ-ray/H₂O₂ And Chemistry Methods

Sludge contains large amounts of recyclable material, containing higher content protein which can be used to produce condensate protein solution after hydrolysis, filtration, concentration and other processes. To replace propagation proteins, the obtained protein can be used for foaming agent of foam concrete and foam fire extinguishing agent. However, except for price advantage, the protein still is difficult to compete with propagation proteins foaming agent because it has some defects such as odor, color depth, and inferior foamability. In order to improve these disadvantages of sludge protein solution, the research, using ⁶⁰Coγ-ray/H₂O₂ method and chemistry method on improvement in performances of sludge protein foaming solution, was perfomed. The main contents were listed:In chemistry method, to take foamability and sensory quality as objective functions, the influences of the concentration of the protein solution, temperature, pH value and various additives on the each objective values were studied by single-factor experiments. The effective significance of various factors on performances of protein solution was analyzed and the process conditions were optimized by the orthogonal experiment. Results showed that the performances of the sludge protein solution were desirable when the concentration of the sludge protein solution was 25% （300mL）, temperature 50℃, pH value 12, tea polyphenols 0.4g,β-Cyclodextrin 0.8g, sugar 0.5g and operation time 40min. Under the conditions, the foamability was 22.7cm, the foam stability 22.2cm, the decolorization percentage 43.1% and the sensory score 4.19.⁶⁰Coγ-ray/H₂O₂ method, improving performances of sludge protein foaming solution, was more feasible than either ⁶⁰Coγ-ray alone or H₂O₂ alone. And the significant influence of the factors such as concentration of the protein solution, pH value, H₂O₂ additive amount and irradiation dose on various objective functions of the sludge protein solution was researched by orthogonal experiments. The experimental results indicated that the effect of H₂O₂ on foamability was remarkable; the effects of pH on foam stability, decolorization percentage and sensory quality were remarkable, whereas the effects of protein solution concentration on each objective value were all not prominent. The optimization process conditions were obtained by using multi-objective optimization, and the results as follows: pH value was 8.7,H₂O₂ 0.4% （volume ratio） and irradiation dose 2.0kGy,under this condition, the decolorization percentage was 64.1401%, the foamability 22.1520cm, the foam stability 20.5116cm and the sensory score 3.2070. The reaction mechanism of action processes by the ⁶⁰Coγ-ray alone, the H₂O₂ alone and the ⁶⁰Coγ-ray/H₂O₂ were analyzed, degradation kinetics model of colored compound was deducted. The existence of synergetic effect on ⁶⁰Coγ-ray/H₂O₂ method was demonstrated, aggrandizement factorial was 14.29.Finally, the feasibility study on the improved protein foaming solution by ⁶⁰Coγ-ray/H₂O₂ method and chemistry method were carried out. The researches demonstrated that they were both feasible to improve performances of sludge protein solution. But the cost of chemistry method was higher. To take social benefit, economic benefit, environmental benefit and process into consideration, ⁶⁰Coγ-ray/H₂O₂ method possessed marked advantage.