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Alum residuals were collected from a water treatment plant and used for improving the photocatalytic degradation of humic acid (HA) by combinations of zinc oxide (ZnO) and powdered residuals from a water purification plant (PRWPP). The influence of operating conditions such as initial humic acid concentration, pH, irradiation time, PRWPP to ZnO ratio, catalyst dose, and light illuminance have been investigated. The optimum PRWPP to ZnO ratio was 10:90. Using the prepared composites instead of bare ZnO raised the HA removal efficiency from 85.5% to 97.8%, and from 38% to 48.1% at catalyst doses of 1.2 g/l and 0.4 g/l, respectively. Moreover, it reduced energy consumption from 210.4 to 166.2 Wh per mg of HA. An artificial neural network model (ANN) was developed to predict the removal efficiency under different operating conditions. The optimum ANN structure yielded a coefficient of determination (R2 = 0.993). A modified Langmuir-Hinshelwood pseudo-first-order model was used for describing the degradation kinetics at different initial concentrations of HA. HIGHLIGHTS Adding PRWPP enhanced the removal efficiency, reduced the ZnO dosage, and reduced the energy consumption.; PRWPP addition had a positive outcome on the environment, and its impact was confirmed using an ANN model.; HA photocatalytic degradation was found to be dependent on catalyst dosage, initial HA concentration, pH, retention time, and light illuminance.;

Lettuce plants were grown under sandy soil conditions in the private farm of Ahmed Orabi organization, Cairo Governorate Egypt, between 15th November 2009 and 15 January 2010. The experiment was conducted to assess the effects of different nitrogen sources, slow release N (urea-formaldehyde) and fast release N (urea) containing fertilizers at the rates of 0, 60, 90 and 120 kg N ha-1 applied alone or combined with potassium sulphate, on lettuce plant yield. Results indicated that application of different sources of N alone or combined with potassium sulphate gave the highest fresh dry weight per plant and total lettuce yield per hectare compared with the control. The highest dry weight of lettuce was achieved with the combination of urea and potassium sulphate. Although fertilization made with the combination of urea and potassium sulphate resulted in the highest P, K, Zn and Mn contents in lettuce plant, fertilization with urea alone gave the highest N and Fe contents. The lowest content of nitrate in lettuce plants was recorded with the fertilization of urea only or with the combination of urea and potassium sulphate. Application of the combination of urea and potassium sulphate induced the highest protein content in plants. The results indicated that application of urea-formaldehyde as a slow release nitrogen fertilizer solely or combined with potassium sulphate significantly improved yield and yield quality of lettuce plants grown in sandy soil.