Reuse of dewatered aluminium-coagulated water treatment residual to immobilize phosphorus: Batch and column trials using a condensed phosphate

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 136; no. 2; pp. 108 - 115
• Main Authors: Babatunde, A.O., Zhao, Y.Q., Yang, Y., Kearney, P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-03-2008; Elsevier
• Subjects: Adsorption; Aluminium-coagulated water treatment residual; Applied sciences; Chemical engineering; Condensed phosphate; Disposal; Exact sciences and technology; General purification processes; Pollution; Reuse; Wastewater treatment; Wastewaters; Water treatment and pollution; Disposal; Adsorption; Aluminium-coagulated water treatment residual; Wastewater treatment; Condensed phosphate; Reuse; Water treatment; Particle size; Adsorption capacity; Modeling; Uptake; Continuous process; Amendment; Batchwise; Loading; pH; Waste water purification
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2007.03.013

The aluminium content in dewatered aluminium-coagulated water treatment residual (DAC-WTR) can lead to a high phosphorus (P) removal capacity. Therefore, DAC-WTR has been used as adsorbent/soil amendment to remove P in several studies, focusing mostly on orthophosphates (ortho-P). This study is concerned with extending such reuse of DAC-WTR to remove P using a condensed phosphate as the model P source. Using a 48
h equilibration time and a 1.18
mm (mean particle size): (1) P removal was found to increase with increasing DAC-WTR dosage, but specific uptake of P per mass of DAC-WTR was decreased. (2) A maximum adsorption capacity of 4.52
mg-P/g of DAC-WTR was obtained at a pH of 4.0.
In the continuous flow test, P removal efficiency decreased from 90 to 30% when loading was increased from 3.9 to 16.5
g-P/m
2
day. An average 45% removal efficiency was obtained after an intentional P loading surge. At the end of the continuous flow test, an operating removal capacity of 2.66
mg-P/g of DAC-WTR was determined which was 83.3% of the adsorption maxima obtained in the batch tests. There was no excessive loss of solids during the continuous flow test and aluminium content in the effluent remained below 0.1
mg-Al
3+/l. These results have demonstrated that dewatered DAC-WTR can further be used as a low-cost adsorbent media for condensed phosphate removal.