Application of Hellenic Natural Zeolite in Thessaloniki industrial area wastewater treatment

Abstract

The treatment of wastewater (initial pH 7.7) from Sindos industrial area of Thessaloniki (Greece) with different proportions (0.1, 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4 g) of Hellenic natural zeolite (HENAZE), resulted in overflowed clear water of pH 7.4–7.3, free of odours and improved by 69–76% for the chemical oxygen demand, 54–70% for nitrate (), over than 97% for the P₂O₅ content, 33% to over than 50% for Pb and 77% to over than 88% for Cr. The treatment process gave also as precipitate an odourless and cohesive zeosludge which is suitable for safe disposal. The HENAZE comprises very high-quality HEU-type zeolitic tuff, containing 86 wt.% HEU-type zeolite (clinoptilolite-heulandite), 4 wt.% mica + clay minerals, 5 wt.% quartz + cristobalite + tridymite, and 5 wt.% feldspars. The HENAZE cannot be used as feed additive for animals and consequently as nutrition supplements, since it contains SiO₂ minerals (quartz, cristobalite, tridymite), while chemically, is suitable for use as soil conditioner, since the concentration of trace elements (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) are lower than the maximum allowable concentrations for agricultural soils.

Keywords:

• HEU-type zeolite
• Clinoptilolite
• Heulandite
• Hellenic Natural Zeolite
• Wastewater purification
• Water quality

Acknowledgements

The authors wish to thank the GEO-VET N. Alexandridis & Co. O.E., for the supply of the HENAZE sample. E. Tziritis would like to thank the Research Committee of the Aristotle University of Thessaloniki for partly financing his post-doc research, a part of which is presented in this paper.