Leaching behaviour of mercury from hazardous solid waste generated by chlor-alkali industry

Y Busto,X Cabrera,F M G Tack

doi:10.1051/e3sconf/20130110008

Y Busto, X Cabrera + Show 1 more

Open Access

https://doi.org/10.1051/e3sconf/20130110008

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Abstract

Through the conventional chlor-alkali production process, highly mercury (Hg) contaminated waste sludge is produced. Improper handling and disposal of this sludge may cause an environmental hazard. The leaching behaviour of Hg of land disposed mercurial sludge, originating from a chlor-alkali plant that still is in operation, was investigated using the German DIN 38414-S4 test. The total mercury content of the samples was above 1500 mg/kg, allowing the material to be classified as hazardous and high mercury waste. Concentrations of Hg in the leachates were higher than 0.02 mg/l stipulated by the 1991 EEC Landfill Directive Draft as a maximum limit for a waste that is to be landfilled. Total Hg contents and leachability differed markedly between the samples, pointing to a heterogeneity in the production of the sludge. The more limited release of Hg from one of the samples might reflect an ageing effect, or might reflect a better quality of the stabilization process at the time of production. Results indicate that the approach used to stabilize the sludge has not been sufficiently effective, and warrant caution about existing disposal sites and future management of these mercury containing waste materials.

Highlights

Mercury-cell chlor-alkali plants (MCCaP) produce chlorine and caustic soda by electrolysis of brine, using mercury as the cathode
Large quantities of mercury are handled. This process is based on 19th century technology, MCCaPs around the world still account for roughly 15% of the global mercury demand, and are a significant source of local and global mercury pollution (Biester et al, 2002; Ulrich et al, 2007)
Mercury total contents differed by a factor of three, pointing to a marked variability in the production of mercurial sludge

Summary

Introduction

Mercury-cell chlor-alkali plants (MCCaP) produce chlorine and caustic soda by electrolysis of brine, using mercury as the cathode. This process is based on 19th century technology, MCCaPs around the world still account for roughly 15% of the global mercury demand, and are a significant source of local and global mercury pollution (Biester et al, 2002; Ulrich et al, 2007). This process is not anymore considered good industrial practice and is increasingly being replaced by more environmentally friendly technologies such as those involving the use of diaphragm and membranes cells (Mukherjee et al, 2004). Thousands of tons of mercurial sludge are currently stored in the surroundings of the plant, constituting a possible hazard to human health and environment

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