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Sedimentation tanks have a vital role in the overall efficiency of solid particles removal in treatment units. Therefore, an in-depth study these tanks is necessary to ensure high quality of water and increasing the system efficiency. In this work, an experimental rectangular sedimentation tank has been operated with and without a baffle to investigate the system behaviour and effectiveness for the reduction of solid particles. Turbid water was prepared using clay, which was collected from the water treatment plant of Al Maqal Port (Iraq), mixed with clear water in a plastic supply tank. Raw and outflow samples were tested against turbidity after plotting a calibration curve between inflow suspended solids versus their corresponding turbidity values. The key objective was to assess the impact of different flow rates, particle concentrations, heights and positions of the baffle on the system efficiency. Findings showed that the tank performance was enhanced significantly (p < 0.05) with the use of a baffle placed at a distance of 0.15 of tank length with height equal to 0.2 of tank depth. Higher removal efficiency (91%) was recorded at a lower flow rate (0.015 dm³·s-1) and higher concentration (1250 mg·dm-3), as the treatment efficiency enhanced by 34% compared with the operation without a baffle. Placing the baffle in the middle of the sedimentation tank produced the worst results. System efficiency for solids removal reduced with increasing baffle height. Further research is required to evaluate the efficiency of an inclined baffle. [ABSTRACT FROM AUTHOR]

Drinking water contamination by fluoride component (F-) is considered as a main public problem in Basra city. The current study highlights on the removal of (F-) from drinking water using effective and low cost materials namely, banana shell and new technical that prepared from orange shell loaded with Zirconyl chloride solutions (Z-r4 (O-H)8 (H2-O)16] C18 (H2- O)12) to develop active adsorption sites for fluoride . High removal efficiency of 94.4 was achieved using fixed bed column loaded (Zc-dejr) under optimum operating conditions, 15.1 ppm of feed concentration, 4.5 pH of feed solution and 4 cm of bed depth. Result of breakthrough profile showed that Thomas was coincided well with the experimental data. Two model, Pseude first order and Pseudo second order where used for finding the mechanism of adsorption kinetics for fluoride (F-) removal by two-bio adsorbents. The result showed that the external adsorption besides to the intra-particle diffusion contributes to the rate influential step. Lagmaier model gives the better result model for the two adsorbents then Temkin isotherm model (TIM). The final concentration of fluoride in treated water with the banana shell adsorbent was 1 mg/l, and with the new solution (Z-r4 (O-H)8(H2-O)16] C18 (H2-O)12 ) was 0.5 mg /l which is acceptable with the standard World Health Organization (WHO). [ABSTRACT FROM AUTHOR]