Conventional flighted rotary drums usually have flights parallel to the rotating axis, which cannot facilitate the axial motion of the materials in the drum. Here, a new type of horizontal rotary drum with inclined flights and beads was designed. Inclined flights are used to facilitate the axial movement of beads and material, while beads are used as fillers to increase the gas-liquid contact area and to crush the solid materials. We simulated the drum and studied the axial motion of fillers using the discrete element method (DEM). To improve the mass and heat transfer performance, we optimized the distribution of beads in the active phase. The effects of the rotational speed, joint angle, and inlet flow rate in the drum were investigated systematically. The individual effects were evaluated in terms of the mass of particles in the active phase (MAP) and passive phase (MPP), the percentage of the active phase occupied by the particles (OAR), and the axial speed (AS). The response surface methodology (RSM) was used to investigate the significant effects of the interaction between the parameters. The maximum MAP value can be obtained by the following parameters: a rotational speed of 37 rpm, joint angle of 139°, and inlet flow rate of 7.83 kg/s. The interaction between rotational speed and inlet flow rate is the most significant for MAP. The joint angle and inlet flow rate have a significant interactive effect on AS. Besides, the rotational speed, joint angle and inlet flow rate show an interactive effect on OAR and AS. Based on the optimization results, the effect of the inclined angle on the axial motion of beads was also evaluated. The axial motion of the beads occurs mainly in the active phase. Compared to the drum without inclined flights, the drum with inclined flights has an enhanced axial speed increased by 26%. This study will be helpful for the design and optimization of drums with inclined flights.

In this paper, refined sugar wastewater (RSW) is treated by electrodialysis (ED) coupled with an upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR). The salt in RSW was first removed by ED, and then the remaining organic components in RSW were degraded by a combined UASB and MBR system. In the batch operation of ED, the RSW was desalinated to a certain level (conductivity < 6 mS·cm⁻¹) at different dilute to concentrated stream volume ratios (V_D/V_C). At the volume ratio of 5:1, the salt migration rate J_R and COD migration rate J_COD were 283.9 g·h⁻¹·m⁻² and 13.84 g·h⁻¹·m⁻², respectively, and the separation factor α (defined as J_COD/J_R) reached a minimum value of 0.0487. The ion exchange capacity (IEC) of ion exchange membranes (IEMs) after 5 months of usage showed a slight change from 2.3 mmol·g⁻¹ to 1.8 mmol·g⁻¹. After the ED treatment, the effluent from the tank of the dilute stream was introduced into the combined UASB-MBR system. In the stabilization stage, the average COD of UASB effluent was 2048 mg·L⁻¹, and the effluent COD of MBR was maintained below 44–69 mg·L⁻¹, which met the discharge standard of water contaminants for the sugar industry. The coupled method reported here provides a viable idea and an effective reference for treating RSW and other similar industrial wastewaters with high salinity and organic contents.

In this study, a new type of rotary dryer filled with inert alumina ceramic bead (ACB) fillers was introduced to treat the industrial wastewater, e.g., the high-salt wastewater and landfill leachate. Numerical simulations based on the Discrete Element Method (DEM) on the motion trajectory of ACB fillers in the rotary dryer were conducted, and the parameters of flight structure, rotational speed, and filling degree on the dynamic behavior of ACB fillers were optimized. Under various rotational speeds and filling degrees, the experimental results fit the numerical-simulated results very well. The optimized flight configuration was the straight flights with a length of 65 mm, and the optimized rotational speed and filling degree were 35 rpm and 15%, respectively. Under the optimized condition, both the response variables, the mass of particles in the airborne phase (MAP) and the percentage of occupied area in the airborne region (OAR), have the optimal values, in which the dryer will have a better drying performance. Besides, the lower-right area of the drum is empty which is convenient for the installation of the inlet pipe. The drying experiments of industrial wastewaters were also studied using this ACB filled rotary drum dryer under the optimized conditions. Under the optimal operational conditions, the evaporation capacities of the high-salt wastewater and landfill leachate could reach as high as 49.7 kg/h and 90 kg/h, respectively. This study highlights the integration of evaporation and drying processes of this novel ACB filled rotary dryer and provides an efficient and zero-liquid-emission strategy for the thermal treatment of industrial wastewater.

The removal of dissolved organic matter (DOM) from seawater before the reverse osmosis (RO) processes is crucial for alleviating organic fouling of RO membranes. However, research is still insufficiently developed in the comparison of the effectiveness of integrating coagulation with ultrafiltration (UF) or sand filtration (SF) in the pretreatment stage of seawater reverse osmosis (SWRO) for the removal of DOM. In this study, we investigated the effect of pretreatment technologies on RO fouling caused by DOM in seawater, including the integration of coagulation and sand filtration (C-S pretreatment) and the integration of coagulation and ultrafiltration (C-U pretreatment). Both integrated pretreatments achieved comparable DOM removal rates (70.2% for C-U and 69.6% for C-S), and C-S exhibited enhanced removal of UV-absorbing compounds. Although C-U was more proficient in reducing the silt density index (below 2) compared to C-S (above 3) and improved the elimination of humic acid-like organics, it left a higher proportion of tyrosine-protein-like organics, soluble microbial by-product-like organics, and finer organics in the effluent, leading to the formation of a dense cake layer on RO membrane and a higher flux decline. Therefore, suitable technologies should be selected according to specific water conditions to efficiently mitigate RO membrane fouling.

The separation of a toluene/methanol/water ternary mixture is a difficult task due to the toluene/water and toluene/methanol azeotropes. In this article, low-energy pervaporation is proposed for the separation of the ternary azeotrope toluene–methanol–water. This work investigates the effects of feed temperature, feed flow rate, and vacuum on pervaporation and compares the energy consumption of pervaporation with that of distillation. The results showed that at the optimized flow rate of 50 L/h and a permeate side vacuum of 60 kPa at 50 °C, the water and methanol content in the permeate was about 63.2 wt.% and 36.8 wt.%, respectively, the water/ methanol separation factor was 24.04, the permeate flux was 510.7 g/m²·h, the water content in the feed out was reduced from 2.5 wt.% to less than 0.66 wt.%, and the dehydration of toluene methanol could be realized. Without taking into account the energy consumption of pumps and other power equipment, pervaporation requires an energy consumption of 43.53 kW·h to treat 1 ton of raw material, while the energy consumption of distillation to treat 1 ton of raw material is about 261.5 kW·h. Compared to the existing distillation process, the pervaporation process consumes much less energy (about one-sixth of the energy consumption of distillation). There is almost no effect on the surface morphology and chemical composition of the membrane before and after use. The method provides an effective reference for the dehydration of organic solvents from ternary mixtures containing toluene/methanol/water.

Potassium phosphate (K₃PO₄) is a common inorganic compound with broad applications in agriculture and industry. Although the traditional thermal method of preparing K₃PO₄ by reacting phosphoric acid with potassium hydroxide can obtain high-quality products, it consumes a lot of energy and has high costs. This study explores the process of preparing K₃PO₄ by Electrodialysis metathesis (EDM). This process uses sodium phosphate (Na₃PO₄) and potassium chloride (KCl) as raw materials and can prepare K₃PO₄ continuously. Under the optimized conditions (operating voltage of 8 V, 0.35 mol/L Na₃PO₄ and 1.05 mol/L KCl in raw flow with the rate of 30 mL/min), the product purity of K₃PO₄ reaches more than 97%, the energy consumption is 1191 kW·h/t, and the cost is about 8314 CNY/ton. Compared with traditional methods, EDM has the advantages of low cost, simple operation, and high utilization rate. This study shows that EDM technology has significant potential in preparing K₃PO₄.