The marble dust as a harmful industrial waste of marble fabrication was evaluated as aneconomical and efficient green adsorbent for Acid Red-1 dye and lead ions. The XRD, XRF, particle size, surface area and zeta-potential measurements were used to characterize the marble dust. The removal efficiency was optimized by studying several parameters such as pH, temperature, contact time, adsorbent dose and initial concentration. The optimum removal was achieved at pH 6, 20C after 60 min in the presence of 2.5g/L marble dust. The rates of adsorption were found to follow the pseudo-second-order model. The results showed better fitting to Freundlich isotherm. The thermodynamic studies revealed that the adsorption process is spontaneous, exothermic and favorable at low temperature. The free energy (∆G°), enthalpy (∆H°), and entropy (∆S°) changes were calculated to predict the nature of adsorption.The removal efficiency was improved by calcination of the marble at 700C. Application for textilewastewater showed high removal efficiency up to 99.9%of inorganic and organic pollutants. The product of treatment was used in the concrete and bricks manufactured, so there is nogeneration of second-order pollutants.

Every year, a large amount of mineral processing wastewater is discharged from various industries into the environment which is considered a challenging task not only because of its large volume, but more importantly, its hazardous components, while its reuse as feedwater without proper treatments causes great harm to the final product of these industries. Cost-effective methods are required to treat a wide range of industrial wastewater in a diverse range of conditions. In this study, a combined hydrocyclone-electrocoagulation system is tried to treat the wastewater for industries with high water consumption and high pollutants such as paper industry, iron and metal forming industry, and marble industry. The effects of the hydrocyclone operational parameters, such as feed inlet pressure and diameter, vortex finder diameter, apex diameter, and feed solids content, were investigated. In the case, wastewater of paper industry, the following optimum conditions (P = 4.5 bar, ! " = 15.8 mm, ! # = 6 mm, ! $ = 4 mm and % & = 2.3%) were achieved. An overflow of about 90.58% water recovery and 21.45% solid at 75.92% separation efficiency was obtained. The results showed that the hydrocycloneelectrocoagulation treatment has efficiently treated the three different types of industrial wastewater. The chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solid (TS), total suspended solids (TSS), colour and turbidity, were reduced sharply and met the effluent discharge or reuse standards. Also, compared with the hydrocyclone-treated wastewater, the hydrocyloneelectrocoagulation-treated wastewater was found to be more enhanced.

The present paper proposes a new simple strategy to build underwater robots using cheap off-the-shelf components. The proposed strategy successfully achieves real-time operation without requiring expensive special purpose hardware/software. The simple geometry of the proposed design makes it possible to derive an accurate dynamic model of the robot. The dynamic model, hardware/software preprocessing of webcam images, multi-feature Kalman based combining as well as neural networks are used to compensate for the limited sensors and computational resources.