The liquid effluents released from several industries including the pulp and paper industries contain phenol and phenolic compounds. The hazardous phenols and their chlorinated phenolic derivatives from pulp and paper...The liquid effluents released from several industries including the pulp and paper industries contain phenol and phenolic compounds. The hazardous phenols and their chlorinated phenolic derivatives from pulp and paper industries bear the potential to exert deleterious effects on the human health and aquatic ecosystems, if they are released untreated in the environment. Biodegradation of phenolic compounds in the effluent streams from pulp and paper industries is an important eco-friendly method for the removal of toxicity in industrial waste water, while the minimization of formation of these toxic compounds require several in-plant biotechnological techniques such as biopulping and biobleaching. Present paper reviews, the biochemical pathways involved in degradation of phenols and chlorophenols through microorganisms. Various biotechnological strategies involved in minimization and biodegradation of phenol and phenolic compounds and their related environmental engineering aspects such as utility of different bioreactor configurations have been discussed for the treatment of pulp and paper mill effluents.展开更多
A numerical method for predicting fiber orientation is presented to explore the flow properties of turbulent fiber suspension flowing through a stock pump impeller. The Fokker-Planck equation is used to describe the d...A numerical method for predicting fiber orientation is presented to explore the flow properties of turbulent fiber suspension flowing through a stock pump impeller. The Fokker-Planck equation is used to describe the distribution of fiber orientation. The effect of flow-fiber coupling is considered by modifying the constitutive mode.The three-dimensional orientation distribution function is formulated and the corresponding equations are solved in terms of second-order and fourth-order orientation tensors. The evolution of fiber orientation, flow velocity and pressure, additional shear stress and normal stress difference are presented. The results show that the evolutions of fiber orientation are different along different streamlines. The velocity and its gradient are large in the concave wall region, while they are very small in the convex wall region. The additional shear stress and normal stress difference are large in the inlet and concave wall regions, and moderate in the mid-region, while they are almost zero in most downstream regions. The non-equilibrium fiber orientation distribution is dominant at the inlet and the concave wall regions. The flow will consume more energy to overcome the additional shearing losses due to fibers at the inlet and the concave wall regions. The change of flow rates has effect on the distribution of additional shear stress and normal stress difference. The flow structure in the inlet and concave wall regions is essential in the resultant rheological properties of the fiber suspension through the stock pump impeller, which will directly affect the flow efficiency of the fiber suspension through the impeller.展开更多
文摘The liquid effluents released from several industries including the pulp and paper industries contain phenol and phenolic compounds. The hazardous phenols and their chlorinated phenolic derivatives from pulp and paper industries bear the potential to exert deleterious effects on the human health and aquatic ecosystems, if they are released untreated in the environment. Biodegradation of phenolic compounds in the effluent streams from pulp and paper industries is an important eco-friendly method for the removal of toxicity in industrial waste water, while the minimization of formation of these toxic compounds require several in-plant biotechnological techniques such as biopulping and biobleaching. Present paper reviews, the biochemical pathways involved in degradation of phenols and chlorophenols through microorganisms. Various biotechnological strategies involved in minimization and biodegradation of phenol and phenolic compounds and their related environmental engineering aspects such as utility of different bioreactor configurations have been discussed for the treatment of pulp and paper mill effluents.
基金Supported by the National Natural Science Foundation of China （51309118）, the National Key Technology R＆D Program of the Ministry of Science and Technology of China （2011BAF14B01）, the Postdoctoral Science Foundation of China （2013M531282） and the Doctorate Program of Higher Education of China （20120101110121）.
文摘A numerical method for predicting fiber orientation is presented to explore the flow properties of turbulent fiber suspension flowing through a stock pump impeller. The Fokker-Planck equation is used to describe the distribution of fiber orientation. The effect of flow-fiber coupling is considered by modifying the constitutive mode.The three-dimensional orientation distribution function is formulated and the corresponding equations are solved in terms of second-order and fourth-order orientation tensors. The evolution of fiber orientation, flow velocity and pressure, additional shear stress and normal stress difference are presented. The results show that the evolutions of fiber orientation are different along different streamlines. The velocity and its gradient are large in the concave wall region, while they are very small in the convex wall region. The additional shear stress and normal stress difference are large in the inlet and concave wall regions, and moderate in the mid-region, while they are almost zero in most downstream regions. The non-equilibrium fiber orientation distribution is dominant at the inlet and the concave wall regions. The flow will consume more energy to overcome the additional shearing losses due to fibers at the inlet and the concave wall regions. The change of flow rates has effect on the distribution of additional shear stress and normal stress difference. The flow structure in the inlet and concave wall regions is essential in the resultant rheological properties of the fiber suspension through the stock pump impeller, which will directly affect the flow efficiency of the fiber suspension through the impeller.
