Search

The objective of this study is to develop by chemical synthesis of hydroxyapatite, an adsorbent powder to be used for the decontamination of waters by metal ions. Moreover, the effectiveness of chitosan produced from shrimp waste to flocculate turbid suspensions produced from the previous treatment is evaluated. The study of adsorption of Cu and Zn on hydroxyapatite showed a removal efficacy of 88-95% with relatively fast kinetics. Between the two metals, copper presents the higher adsorbing tendency. However, the use of hydroxyapatite, as an adsorbent, generates turbid suspensions which are hardly settleable. For this reason we evaluated the effectiveness of chitosane to flocculate the hydroxyapatite turbid suspensions. The outcome of this study is the great efficacy exhibited by the chitosan to remove the turbidity of various samples of hydroxyapatite of different fractions. The elimination rate after 30 minutes of settling in all cases exceeds 98%. The effect of the dose of chitosane and the effect of pH on the coagulation-flocculation process were studied and the respective results show that the optimal doses range from 0.2 to 2 mg of chitosane/ L corresponding at optimal pH between 6 and 7.

In this paper, application of electrocoagulation using common iron electrode to a simulated photovoltaic wastewater after precipitation with lime (Ca(OH)2) was investigated. Electrocoagulation process delivers the coagulant in situ as the sacrificial anode corrodes, while the simultaneous evolution of hydrogen at the cathode allows pollutant removal by flotation. Several working parameters, such as initial pH, applied potential and distance between the electrodes, were studied in an attempt to achieve higher fluoride removal efficiency. The optimum conditions for the process were identified as pH = 6, the distance between electrodes = 1 and an applied potential of 30 V. Furthermore fluoride removal is under the direct discharge standards.Results showed high effectivenessof the electrocoagulation method in removing fluoride from aqueous solutions.

Chitosan is a natural polymer prepared from crab, shrimp and lobster shells. It has been used as coagulant in water treatment to avoid the human health problems caused by the residual aluminum and chemical polymers in water. In this study, the raw water from Keddara dam characterized by low turbidity was treated using chitosan as primary flocculant and as coagulant aid with aluminum sulfate. The result shows that chitosan was not too efficient as alum, if it is used as primary coagulant for treating Keddara raw water. However, when chitosan was applied as coagulation aid agent with aluminum sulfate, highest turbidity removal (97%) was carried out with 0.2 mgl-1of chitosan after 45 minutes of settling time. The organic carbon contribution on the coagulation flocculation performance is negligible because chitosan is used in small doses. Hence, chitosan could be used as natural coagulant aid for drinking water treatment with lowest risks of organic release.

In this study, the effective performance of electrocoagulation process in the treatment of water solution that is loaded with orthophosphate was investigated using sacrificial iron electrodes. Various operating parameters (e.g., pH, current intensity and supporting electrolyte concentration) were studied in an attempt to achieve a higher removal capacity. Results obtained with synthetic wastewater revealed that the most effective removal of orthophosphate could be achieved when the pH was kept between 5 and 8. The optimum concentration of supporting electrolyte was found to be 2 g/L, which was adjusted using proper amount of NaCl with the orthophosphate concentration of 10 mg/L. In addition, the increase of current intensity, in the range 0.6–2.0 A, enhanced the treatment rate without affecting the energy consumption. The method was found to be highly efficient and relatively fast compared to conventional existing techniques