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HighlightsØ Different chemicals were compared for the coagulation and flocculation of brewery wastewater.Ø Carbon nanotubes can be used as heterogeneous coagulants in the pretreatment of brewery wastewater.Ø Ferric chloride was a more effective coagulant than both functionalised and pristine CNTs. AbstractCoagulation and flocculation treatment processes play a central role in the way wastewater effluents are managed. Their primary function is particle removal that can impart color to a water source, create turbidity, and/or retain bacterial and viral organisms. This study was carried out to investigate whether carbon nanotubes (CNTs) can be used as heterogeneous coagulants and /or flocculants in the pretreatment of brewery wastewater. A series of experiments were conducted in which the efficiencies of pristine and functionalised CNTs were compared with the efficiency of traditional ferric chloride in a coagulation/flocculation process. Turbidity and chemical oxygen demand (COD), including the zeta potential were used to monitor the progress of the 2 coagulation/flocculation process. Both pristine and functionalised CNTs demonstrated the ability to successfully coagulate colloidal particles in the brewery wastewater. Overall, ferric chloride was found to be a more effective coagulant than both the pristine and functionalised CNTs.

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A novel approach to modeling mass transfer in rotary kilns or rotating cylinders is explored. The movement of gas in the interparticle voids in the bed of the kiln is considered, where particles move concentrically with the geometry of the kiln and gas is entrained by these particles. The approach considers a di erential section along the length of a rotary kiln where the gas concentration in the freeboard is assumed to be uniform in that section. A reactor modelling approach has been used to derive e ectiveness factors for the bed as a function of bed ÿll, reaction kinetics and rotation speed. In many cases, the entrained gas becomes depleted within the bed, leading to a simpliÿed model for the bed e ectiveness factor. Experimental data conÿrms the validity of this model for slower rates. At faster rates, mass transfer can be much higher than the model predicts, indicating that other mechanisms, such as dispersion or di usion are also important in these conditions. ?