The adsorption of phosphate ion onto natural reed ( Arundo donax) was studied in this work. The effect of phosphate initial concentration, adsorbent dose, pH, temperature, and salt addition on adsorption uptake was investigated. The results showed that the adsorption uptake is directly proportional to the phosphate ion initial concentration and inversely proportional to the adsorbent's dose and temperature. A maximum adsorption capacity of 16.2 mg/g was observed at neutral pH. The addition of sodium and potassium chlorides has decreased the adsorption uptake. The adsorption isotherms agree better with the Langmuir model. The negative values of (ΔG) and (ΔH) obtained from the thermodynamic study, indicted that the adsorption process is spontaneous and exothermic. The experimental adsorption data were analyzed using three kinetic models: pseudo-first order, pseudo-second order, and intra-particle diffusion model. The pseudo-second-order model presented the best fit with a determination coefficient ( R²) higher than 0.99 and a minimum normalized standard deviation.

Ultrasound is widely used to disinfect drinking water and wastewater due to its strong physical and chemical effects on microorganisms. The aim of this study was to investigate the effect of ultrasound on the destruction of Mycobacterium strain 6PY1. Ultrasound waves (20 kHz or 612 kHz) were used to treat aqueous suspensions of Mycobacterium at different volumes, initial bacterial concentrations, and power densities. At the same power density and the same exposure time, sonication at high frequency resulted in a lower destruction of Mycobacterium sp. 6PY1 (35.5%) than sonication at low frequency (93%). The percentage of removal was not significantly affected by the volume of the irradiated suspension (150-300 ml) or the initial cell concentration (2.15 x 10(-3)-1.4 x 10(-2)mg protein L(-1)). At low frequency, the removal percentage of Mycobacterium sp. 6PY1 increased with increasing the power density, with a constant level reached after a certain power density. At high frequency, the removal percentage of Mycobacterium sp. 6PY1 increased with increasing the power density. The mechanism of cell killing was investigated by examining the effects of OH() radical scavengers such as sodium carbonate. At high frequency the presence of sodium carbonate suppressed the removal process. However, at low frequency the removal process was not affected, thus indicating that OH() radicals have a negligible role in this case. The latter result was supported by ten time's H(2)O(2) production at high frequency greater than that at low frequency.

In the present study, activated sludge has been utilized for the removal of triadimenol pesticide from water. The maximum adsorption capacity was 42.9 mg triadimenol per gram activated sludge obtained at 298 K. The equilibrium data were fitted to Langmuir Freundlich models and it was found that Freundlich model best fit these data with regression coefficient R²=0.947. The kinetic data showed that the rate of triadimenol adsorption is increased with increasing the initial concentration and mixing speed, while decreased with increasing temperature. The two-resistance mass transfer model based on the film resistance homogeneous solid-phase diffusion was used to fit the experimental data. A computer program has been developed to estimate the theoretical concentration–time- dependent curves and to compare them with the experimental curves by means of the best-fit approach. The model predicts that the external mass transfer coefficient k_f was affected by varying the initial triadimenol concentration, the agitation speed and temperature, whereas the diffusion coefficient D_e was affected by the initial triadimenol concentration and temperature.