OPTIMIZATION OF DONNAN DIALYSIS FOR ALUM RECOVERY USING BOX BEHNKEN DESIGN

Dennis Asante-Sackey,Emmanuel Kweinor Tetteh,Lingam Pillay,Sudesh Rathilal

doi:10.12955/cbup.v6.1286

Dennis Asante-Sackey, Emmanuel Kweinor Tetteh + Show 2 more

Open Access

https://doi.org/10.12955/cbup.v6.1286

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Abstract

Most potable water treatment plants use aluminium salts as coagulants. This generates a lot of treatment residue which consist of a high amount of aluminium in the residue matrix. Recovery of the alum-coagulant from the potable water treatment for reuse provides direct process and economic advantages. Donnan Dialysis is an ion exchange process that has a proven advantage in coagulant recovery. The commercial application of this process requires bench scale optimization before implementation. In this study, a response surface methodology is applied to the Donnan system. Incorporated with the Box-Behnken experimental matrix, the main and interactional effects of input variables for optimum alum recovery was determined. The Nafion 117 cation exchange membrane was used. Using experimental results, the quadratic statistical module generated was significant with a low P-value (<0.001). The statistical prediction from experimental results shows that high recoveries of 85-96% can be achieved.

Highlights

Coagulation is an integral physico-chemical process mostly deployed in conventional or hybrid potable water and wastewater treatment for the removal of particulates, natural organic matter, microorganisms, inorganic ions and metal complexes as larger flocs for subsequent removal through a solid/liquid separation chain such as clarification, sedimentation and filtration (Jiang, 2015; Teh & Wu, 2014)
Potable water treatment (PWT) generates residue streams with enormous quantities produced during coagulation
An estimated yearly average of 100,000 tons of residue is generated by a potable water treatment plant whilst a global estimated average of 10,000 tons per day is generated by treatment plants (Ahmad et al, 2016)

Summary

Introduction

Coagulation is an integral physico-chemical process mostly deployed in conventional or hybrid potable water and wastewater treatment for the removal of particulates, natural organic matter, microorganisms, inorganic ions and metal complexes as larger flocs for subsequent removal through a solid/liquid separation chain such as clarification, sedimentation and filtration (Jiang, 2015; Teh & Wu, 2014). The wide use of mineral coagulants is cost effective for the removal of contaminants. Most of these treatment facilities use hydrolytic salts of aluminium and iron as coagulants due to their relatively low cost, market availability and easy storage with alum as a dominating coagulant (Niquette et al, 2004). Potable water treatment (PWT) generates residue streams with enormous quantities produced during coagulation. Sustainable management strategies for residue produced have generated environmental pollution, health risks and economic impact concerns. The residue management method exposes soil surface and underground water, to contamination through rain water runoff, leaching and infiltration. These occurrences results in the increased cost of disposal per volume per area of land (Babatunde & Zhao, 2007)

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