Phosphorus treatment of secondary municipal effluent using oven-dried alum residual

Abstract

This study aims to investigate the effectiveness of alum residuals generated during drinking water treatment for adsorption of phosphorus from secondary municipal effluent. Bench-scale experiments (batch and fixed bed column tests) were conducted using oven-dried alum residuals. Experimental results observed maximum phosphorus removal of 91%–98% using alum residual concentrations of 4 g/L to 16 g/L. Oven-dried alum residual was a more effective adsorbent for orthophosphate phosphorus than total phosphorus. Effluent pH levels were suitable for surface water disposal with little or no lime addition. Aluminum leaching from oven-dried alum residual was not high enough to cause toxicity for aquatic species in surface water. Oven-dried alum residuals were also able to adsorb organic matter. The results indicated that oven-dried alum residuals have potential to provide a low cost technological solution for small- and medium-sized municipalities.

Keywords:

• BOD₅
• alum residuals
• fixed bed column test
• Freundlich isotherm
• Langmuir isotherm
• fraction leaching
• pore volume processed

Acknowledgments

The authors want to acknowledge the Canadian Water Network and the Natural Science and Engineering Research Council for their financial support and our partner municipality in Atlantic Canada for supplying secondary municipal effluent and technical insight.