The Influence of Detention Time, Flow Rate and Particle Size in the Removal of "Copper" from Water Using Limestone Filtration Technology -Laboratory Scale—

Abstract

The concern over increasing needs for drinking water and awareness for development of systems to improve water quality both for drinking purposes and for effluents from wastewater treatment and industrial facilities have provided incentives to develop new technologies and improve performance of the existing one. Adsorption technology has many advantages over other treatment methods such as simple design, low investment cost, limited waste production, etc. Synthetic water with a dosing of artificial copper solution (Cu No3) was passed through a PVC column (15 cm diameter, 100 cm length) containing limestone as a filter media in three different sizes, using three different hydraulic rates, and three initial influent copper concentrations (7.04, 4.39, 1.72) ppm .For this study, three experiments have been conducted; continuous batch and field experiment. The up flow roughing filtration is the suitable technique to recover heavy metals present in aqueous solutions, without the need of adding further substances. The filtration results demonstrated that the smaller size of filter media (3.75) mm gave higher removal efficiency (93.75 – 98.80) % than larger filter media (9.50) mm which gave removal efficiency of (67.61 – 94.0) %. This is due to the large specific surface. The smaller size of limestone achieved the longer detention time (49) min, so the removal of Cu was more than (90) % for the (50) min of experiment. At lower flow rate (0.16) L/min, the removal efficiency was higher than at higher flow rate (0.77) L/min. At high flows, there is a reduced period of surface contact between the particles and copper solution. This study also involved three different batch experiments .The removal efficiency was (93- 97) % for the three types of limestone which indicates the importance of limestone media in the removal process. This also indicates that the removal efficiency was increasing with the increase of the limestone volume. Field experiment has been conducted using wastewater from Al- Dura Electric Station on the three types of limestone so that to ensure the laboratory tests. It was achieved good removal efficiency range from (87.5) % to(97.5) % at the high adsorbent dose .To calibrate the physical model, a computer program of multiple regressions is used to assess the relative importance of the predicted variables. The partial correlations indicate that influent concentration of copper, surface loading (flow rate), and detention time are the most important variables while the size of limestone is not important as others.