Phosphorus removal from wastewater using oven-dried alum sludge

Abstract

The present study deals with the removal of phosphorus from wastewater by using oven-dried alum sludge (ODS) as adsorbent that was collected from Al-Qadisiya treatment plant (Iraq); it was heated in an oven at 105 C°for 24h and then cooled at room temperature. The sludge particles were then crushed to produce a particle size of 0.54.75mm. Two modes of operation are used, batch mode and fixed bed mode, in batch experiment the effect of oven-dried alum sludge doses 1050g/L, pH of solution 58 with constant initial phosphorus concentration of 5mg/L, and constant particle size of 0.5mm were studied. The results showed that the percent removal of phosphorus increases with the increase of oven-dried alum sludge dose, but pH of solution has insignificant effect. Batch kinetics experiments showed that equilibrium time was about 6 days. Adsorption capacity was plotted against equilibrium concentration, and isotherm models (Freundlich, Langmuir, and Freundlich-Langmuir) were used to correlate these results. In the fixed bed isothermal adsorption column, the effect of initial phosphorus concentration (C o) 5 and 10mg/L, particle size 2.36 and 4.75mm, influent flow rate (Q) 6 and 10L/hr, and bed depth (H) 0.150.415m were studied. The results showed that the oven-dried alum sludge was effective in adsorbing phosphorus, and percent removal of phosphorus reaches 85 with increasing of contact time and adsorbent surface area (i.e., mass of adsorbent 50g/L with different pH). Copyright © 2012 Wadood T. Mohammed and Sarmad A. Rashid.