Phosphorus Removal from Wastewater Using Oven-Dried Alum Sludge

Abstract EN

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 105C∘ for 24 h and then cooled at room temperature.

The sludge particles were then crushed to produce a particle size of 0.5–4.75 mm.

Two modes of operation are used, batch mode and fixed bed mode, in batch experiment the effect of oven-dried alum sludge doses 10–50 g/L, pH of solution 5–8 with constant initial phosphorus concentration of 5 mg/L, and constant particle size of 0.5 mm 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 (Co) 5 and 10 mg/L, particle size 2.36 and 4.75 mm, influent flow rate (Q) 6 and 10 L/hr, and bed depth (H) 0.15–0.415 m 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 50 g/L with different pH).