Phosphorus Removal Using Lignite Fly Ash

• Published in: Energy sources. Part A, Recovery, utilization, and environmental effects Recovery, utilization, and environmental effects, 2015-04, Vol.37 (7), p.735-741
• Main Authors: Masto, R. E., Verma, R., Ram, L. C., Selvi, V. A., George, J., Sinha, A. K.
• Format: Article
• Language: English
• Subjects: adsorption; fly ash; lignite; phosphorus; precipitation
• ISSN: 1556-7036; 1556-7230
• DOI: 10.1080/15567036.2011.592927

Phosphorus (P) release to surface waters leads to serious pollution. The 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 solid-liquid ratio, maximum carrying capacity, etc. need to be yet optimized.