Abstract: Constructed wetlands (CWs) have evolved as some of reliable wastewater treatment technologies. Various types of CWs differ in their main design characteristics and in processes responsible for pollutant removal. Classification of CWS is based on the type of vegetation used and hydrological parameters involved and can thus be classified as free water surface or subsurface flow systems. Further, subsurface flow systems can be classified according to flow direction as vertical or horizontal. This study considers horizontal subsurface flow constructed wetlands (HSFCWs) which introduces the mechanistic, dynamic compartmental model-Constructed Wetlands 2D (CW2D). The model has successfully been utilized to evaluate the performance of vertical flow constructed wetlands and is being tested on HFCWs. An outdoor pilot scale HSFCW system was established in Nakuru, Kenya. CW2D was calibrated, validated and used to simulate hydraulic performance of HSFCW system. The model was used in predicting effluent concentrations of the main greywater pollutants. In general, the results obtained showed a good match with the measured data. CW2D is an effective tool for evaluating the performance of CWs and can provide insights in treatment problems at an existing CW. The same methodology can be used to optimize existing systems.Abstract: Constructed wetlands (CWs) have evolved as some of reliable wastewater treatment technologies. Various types of CWs differ in their main design characteristics and in processes responsible for pollutant removal. Classification of CWS is based on the type of vegetation used and hydrological parameters involved and can thus be classified as free wate...Show More
Abstract: In this work, activated carbon was prepared from apricot stone (ASAC) waste to remove the toxic heavy metal ions (Aluminum ions and zinc ions) from aqueous solutions. The effect of different parameters such as PHs, adsorbent dose, the initial heavy metal ions concentration and contact time were investigated. Adsorption isotherm, kinetics and thermodynamics of metal ions on ASAC were studied. Equilibrium data were fitted to the Langmuir and Freundlich isotherm models. Langmuir isotherm provided the best fit to the equilibrium data with maximum adsorption capacity. Kinetic studies were also undertaken in terms of pseudo-first-order and pseudo-second-order kinetic models for heavy metal ions on ASAC. The adsorption process follows the pseudo- second order kinetic with high coefficients correlation. The thermodynamic parameters ∆G°, ∆H° and ∆S° determined, showed that the adsorption of heavy metal ions onto ASAC was feasible, spontaneous and endothermic. The results showed that ASAC is an efficient adsorbent for the adsorptive removal of heavy metal ions from aqueous solutions.Abstract: In this work, activated carbon was prepared from apricot stone (ASAC) waste to remove the toxic heavy metal ions (Aluminum ions and zinc ions) from aqueous solutions. The effect of different parameters such as PHs, adsorbent dose, the initial heavy metal ions concentration and contact time were investigated. Adsorption isotherm, kinetics and thermo...Show More
