Phosphorus Removal Using Lignite Fly Ash

development of technology for P removal offers the opportunity for abatement of environmental hazards and recycling. Fly ash is widely available and a cheap adsorbent; its alkaline properties make it interesting for precipitation of phosphates. An attempt was made to study the P removal ability of lignite fly ash. In order to determine the phosphate removal capacity of fly ash and the effect of adsorbent quantity (5 and 10 g per 100 ml), temperature (28 and 50°C), retention time (5 and 30 min) on P removal, sorption studies were conducted using phosphate solutions containing 20, 50, 100, 150, and 200 mg/l P. The results showed that the lignite fly ash was able to remove even 100% of 20 mg/l P at 10 g adsorbent with 30 min retention time at 28°C. The P removal capacity decreased with increase in P concentration; the removal was 86.51% at 200 mg/l P. The adsorbent quantity significantly influenced the P removal; the average removal was 94.81% at 5 g and 97.5% at 10 g. The Langmuir adsorption maximum was the highest for 5 g of fly ash–30 min equilibrium at 28°C (40.98 mg/kg). The adsorption maxima decreased with increase in temperature, however, the factor related to bonding energy has increased at 50°C. Altogether the study revealed that the lignite fly ash could be successfully used for instantaneous P removal at ambient conditions; however, other parameters like solidliquid ratio, maximum carrying capacity, etc. need to be yet optimized