Phosphate removal from wastewater using spent alum sludge

Abstract

A small-scale continuous flow system, which allows recycling of effluent, has been set up to study the phosphate adsorption ability of air-dried alum sludge from wastewater effluent, and the variation of nitrogen species in wastewater associated with phosphate removal. Initial phosphate removal was rapid, with phosphate levels being reduced by approx. 55% in the first 20 minute of the experiment. The variation of nitrogen species present in the wastewater showed a negative correlation with the concentration of phosphate. Thus, the concentration of ammonia increased from 0 ppm to 16 ppm, while the concentration of nitrate increased from 0 ppm to 98 ppm in the first 20 minutes; nitrite concentrations were found to be insignificant. Very similar phosphate removal patterns and changes in nitrogen species concentrations were exhibited for different batches of alum substrate; the adsorption capacity of spent alum was found to be approx. 0.30–0.33 mg phosphate per 1 g of air-dried spent alum.

Constructive Approaches Toward Water Treatment Works Sludge Management: An International Review of Beneficial Reuses

“…As regards major pollutants in wastewaters, extensive studies have been conducted into the feasibility of using waterworks sludge as an adsorbent for phosphorus removal in wastewaters (Huang and Chiswell, 2000;Zumpe et al, 2002;Georgantas and Grigoropoulou, 2005;Kim et al, 2003;Babatunde et al, 2005 andYang et al, 2006a&b). The basic idea is that the abundant amorphous aluminium and ferric ions in waterworks sludge can become valuable for phosphorus removal in wastewaters since such ions have been demonstrated to enhance the processes of adsorption and chemical precipitation that aids phosphorus immobilization (de-Bashan and Bashan, 2004).…”

Characteristics and mechanisms of phosphate adsorption on dewatered alum sludge

“…In other instances, conjunctive evidences from literature have also shown that alum sludge can help remove phosphorus in wastewater. This is attributed to the abundant aluminum ions in the alum sludge, which enhance the processes of adsorption and chemical precipitation that help to remove such pollutants from wastewater [5][6][7]. However, an in-depth understanding of the mechanisms and characteristics of phosphorus adsorption by the alum sludge is crucial to its effective utilization as an adsorbent material.…”

Reuse of Aluminum‐based Water Treatment Sludge to Immobilize a Wide Range of Phosphorus Contamination: Equilibrium Study with Different Isotherm Models

“…Overall, this study provides a comparison of the four commonly used adsorption isotherms models to best describe P adsorption onto Al-WTS. It should be noted that past studies have extensively demonstrated the effectiveness of Al-WTS for P immobilization (1,(7)(8)(9)(10)(11). Therefore, the input of this study lies in exploring the best isotherm which could be employed in designing and predicting adsorption process in future and large scale application.…”