Journal of Applied Research in Water and Wastewater
Volume:3 Issue: 2, Summer and Autumn 2016

Eggplant hull (EH) as a waste material was introduced as a new adsorbent through activation process followed by a chemical treatment method using H2O2 and NH3. For the first time, the EH adsorption was used for the adsorptive removal of mercury ion (Hg++) from aqueous solutions and the effects of different parameters, including pH of solution, contact time, temperature, and initial concentration, on the adsorption efficiency were studied. The results revealed that the EH, as an effective adsorbent, has high adsorption activity in higher pH values. The temperature study indicated the endothermic nature of the adsorption processes. Also, the Hg (II) adsorption by EH follows the pseudo first order kinetic model and both Langmuir and Freundlich isotherm models. However, Freundlich adsorption model fitted the experimental data better than Langmuir model. The maximum adsorption capacity of EH was obtained 147.06 mg/g which was higher than most conventional adsorbents. The surface activity of EH was estimated using iodine method as 300 mg/g.

Roll waves appear as successive transitions from super- to sub-critical flows by passing through moving hydraulic jumps. Such discontinuous periodic waves propagate in a staircase pattern at constant wave celerity. On the basis of nonlinear shallow water (NLSW) equations, a finite volume model is presented to study the evolution of roll waves in inclined steep channels. The numerical model exploits the total variation diminishing version of weighted average flux (TVD-WAF) explicit method to solve the homogeneous NLSW equations. An implicit trapezoidal time integration operator is implemented for the treatment of source term which includes contributions from both the channel slope and frictional resistance. The simulated surface profile and flow velocity are in well agreement with available analytical solution for roll waves. The time evolution of wave amplitude under different undisturbed Froude numbers are investigated numerically and compared with theoretical predictions. Temporal decay of initial disturbance is discussed in which case roll waves no longer form. The observed agreement implies the efficiency and accuracy of the present scheme for roll wave modeling.

Advanced oxidation technologies based on microwave and photocatalysis have a higher potential for the treatment of environmental persistence and reclariant compounds. The present work investigates the treatment of Bismarck Brown dye using effects of photocatalysis (UV) and microwave (MW) and their sequential combination. It has been observed that the sequential combination of MW followed by UV (MW/UV) has shown the higher performance as compared to the effects of MW and UV alone. The maximum degradation for MW/UV observed is (44.1±0.5 %). It was much higher than UV (9.2±0.08 %), and MW (30.8±0.6 %). The process efficiency was further increased in the presence of the catalyst such as hydrogen peroxide, zinc oxide, and titanium dioxide. The highest degradation was observed in the presence of titanium oxide (82.9±0.4 %) as a catalyst loading of 0.1 g/L in 100 min. Total organic carbon (TOC) measured for quantification of mineralization of BB-Y. The maximum removal of TOC was 38.2±0.32 % in a sequential combination of MW-UV (presence TiO2).

In particular, the inappropriate/inevitably discharge of dye-containing effluents is undesirable because of their color, resistant to the biological treatment systems, toxic, and their carcinogenic or mutagenic nature to life forms. About fifty percent of the washing dye liquor is discharged into the water environment. Fe3O4@SiO2@TiO2 nanoparticles, were prepared, characterized and tested as photocatalyst in the removal of Reactive Black B (RBB) dye by a photocatalytic process. The effect of photocatalyst concentration, pH and temperature in the photodegradation kinetics is discussed in terms of the Langmuir–Hinshelwood (L-H) model. SEM and TEM characterizations confirmed the Fe3O4@SiO2@TiO2 nanoparticel, revealed that the obtained particles a spherical morphology with sizes about 100 nm. The DRS pattern of Fe3O4@SiO2@TiO2 shows the energy band gap value of photocatalyst is 2.75 eV. The presence of Fe3O4, SiO2 and anatase TiO2 in the as-synthesis magnetic nanoparticle were confirmed by FTIR and XRD analysis. The Fe3O4@SiO2@TiO2 photocatalyst in combination with ultraviolet irradiation and under optimal conditions can destroy 100% of RBB after 120 min. Furthermore, the magnetic photocatalyst was efficiently separated from the solution with the help of a magnet and shown the capable of reusability up to 10 times without reducing their efficiency.

In this paper an attempt has been made to study the effects of floodplains width and discharges on flow field in prismatic compound channels. A three-dimensional Computational Fluid Dynamic (CFD) model is used to predict the velocity distribution, secondary flow circulation and boundary shear stress in prismatic compound channels with various floodplains widths. The ANSYS-CFX software and three different turbulence models, ,  Explicit Algebraic Reynolds Stress Models (EARSM) and Eddy Viscosity Transport, are used to solve Reynolds Averaged Navier-Stokes equations. The results of the numerical modeling were then compared with experimental data on prismatic compound channels with 100 mm, 200 mm, 300 mm, and 400 mm floodplain widths. The study shows that all turbulence models are capable to predict the depth-averaged velocity in prismatic compound channels, fairly well. However, to compare with the velocity distribution, discrepancy between experimental data and boundary shear stress calculated by numerical modeling are high. Also only  EARSM model is able to predict secondary flow circulations.

A comparative kinetic study of photocatalytic degradation of textile wastewater by UV/TiO2 and UV/ ZnO for removal of chemical oxygen demand (COD), and color was carried out. The effects of some parameters such as the initial concentration of catalyst, initial COD concentration and light intensity on the photocatalytic process were also examined. It was demonstrated that the COD removal by TiO2/UV and ZnO/UV was about 49 %, 33.3 %, and color removal was 30 % and 10 %, respectively. The experiment demonstrated that the photo-degradation efficiency of TiO2 was significantly higher than that of ZnO. On the other hand, the kinetic study shows that decomposition of chemical oxygen demand follows a first-order for processes. The rate of degradation is highly dependent on the initial concentration of TiO2, ZnO and light intensity. A comparison between experimental and calculated degradation rate constants shows that TiO2/UV process gives better results than photocatalytic treatment. Maximum degradation rate was achieved for TiO2/UV at optimum concentrations of TiO2.

When ammonia discharged into water resources, it has a negative effect on aquatic life as a major water pollutant. Therefore, removing of ammonia from wastewaters has become an essential need for last decades concurrent with developing in the industry and agriculture. Hence there are emerged various techniques for removing the solvated ammonia which among them membrane distillation (MD) is the powerful technique for wastewater treatment. In the thermally process of membrane distillation, only volatile molecules are transferred through hydrophobic membrane. The microporous membrane is a barrier for separation of permeate (cool side-liquid or gas phase) from feed (hot side-liquid or gas phase). The vapor pressure gradient is a propulsion force for migration volatile molecules into the permeate side. In this short review paper, we summarized the surveys about membrane distillation techniques in removal of solvated ammonia.