Majeda Khraisheh

This paper investigated the removal of humic substances (HS) from drinking water supplies by adsorption onto granular activated carbon (GAC), iron-coated alumina (AAFS) and ferric oxihydroxide (β-FeOOH). The determination of the rate limiting step of the adsorption process was tested using the pseudo-first and second order kinetic models. Two mixing speeds were considered namely; 200 and 300 rpm. Disintegration (attrition) of the adsorbents occurred above 300 rpm while 200 rpm represented the minimum mixing speed required to keep the solution in suspension. During the first few minutes of adsorption at 300 rpm, strong instantaneous adsorption was observed. Among the three adsorbents, AAFS showed the least affinity for the HS with no instantaneous adsorption at all at 200 rpm. Furthermore, the pseudo-first order model failed to represent the whole range of data while the second order model was the best fit for all the experimental range considered in this study.

Selected biodegradable municipal solid waste fractions were subjected to fifteen different pre-hydrolysis treatments to obtain the highest glucose yield for bio-ethanol production. Pre-hydrolysis treatments consisted of dilute acid (H₂SO₄, HNO₃ or HCl, 1 and 4%, 180 min, 60°C), steam treatment (121 and 134°C, 15 min), microwave treatment (700 W, 2 min) or a combination of two of them. Enzymatic hydrolysis was carried out with Trichoderma reesei and Trichoderma viride (10 and 60 FPU g⁻¹ substrate). Glucose yields were compared using a factorial experimental design. The highest glucose yield (72.80%) was obtained with a pre-hydrolysis treatment consisting of H₂SO₄ at 1% concentration, followed by steam treatment at 121°C, and enzymatic hydrolysis with Trichoderma viride at 60 FPU g⁻¹ substrate. The contribution of enzyme loading and acid concentration was significantly higher (49.39 and 47.70%, respectively), than the contribution of temperature during steam treatment (0.13%) to the glucose yield.