ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Innovative approach to treating waste waters by a membrane capacitive deionisation system

Miša Biro* and Darinka Brodnjak Vončina

^aCIVIS d.o.o., Radvanjska cesta 87, 2000 Maribor, Slovenia

E-mail: misa.biro@civis.si

Abstract: The application of membrane capacitive deionisation was investigated for treating model water samples and real waste waters from the textile industry. For the pre-treatment of waste waters, nanofiltration was integrated in order to prevent scaling and fouling of membranes and electrodes during membrane capacitive deionisation. Different conditions were applied when treating water samples with membrane capacitive deionisation with the aim of optimising conditions for high desalination efficiency and, consequently, for conductivity reduction. The conductivity of waste waters with high salt concentrations was reduced to the required value, below 1.5 mS cm⁻¹.The desalination rates achieved as much as 95 %, depending on the initial conductivity and the different ions present in the water samples. In addition, chemometric characterisation of the samples was performed in order to determine the existence of significant correlations between the monitored parameters: the presence of various ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, Br⁻, F⁻, ${\text{SO}}_{\text{4}}^{\text{2}-},{\text{NO}}_3^{-}$), desalination and water recovery, the duration of each phase and the flow of the solution during each phase. A model for desalination rate prediction was designed using multiple linear regression. It was established that the model values accorded well with the experimental values - the differences between model and experimental values were less than 1 %.

Keywords: membrane capacitive deionisation – conductivity reduction – waste water treatment – chemometric characterisation – multiple linear regression

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0239

Chemical Papers 70 (5) 576–584 (2016)