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Environ Sci Pollut Res (2016) 23:2461424623 DOI 10.1007/s11356-016-6851-6
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Web End = GLOBAL POLLUTION PROBLEMS, TRENDS IN DETECTION AND PROTECTION
Electrochemical wastewater treatment: influence of the type of carbon and of nitrogen on the organic load removal
Annabel Fernandes1 & Joo Coelho1 & Lurdes Ciraco1 & Maria Jos Pacheco1 &
Ana Lopes1
Received: 29 January 2016 /Accepted: 9 May 2016 /Published online: 20 May 2016 # Springer-Verlag Berlin Heidelberg 2016
Abstract Boron-doped diamond (BDD) and Ti/Pt/PbO2 anodes were utilized to perform the electrodegradation of synthetic samples containing humic acid in the presence of different organic and inorganic carbon-containing and nitrogen-containing compounds. The influence of the chloride ion in the degradation process of the different synthetic samples was also assessed. The results showed that the anodic oxidation process can efficiently degrade recalcitrant compounds such as humic acid. The presence of carbonate in solution enhances the nitrogen removal, whereas it hinders the oxidation of the organic compounds. When organic nitrogen is present, it is converted to NH4+, which in turn is oxidized to nitrate and to volatile nitrogen compounds. Hydroxyl radicals are more prone to oxidize the organic nitrogen than the ammonium nitrogen. The presence of chloride enhances the organic matter and nitrogen removal rates, BDD being the anode material that yields the highest removals.
Keywords Persistent organic pollutants . Humic acid . Electrochemical treatment . BDD anode . Ti/Pt/PbO2 anode .
Chloride influence . Nitrogen removal
Introduction
Electrochemical technologies have shown high efficiency in the elimination of persistent pollutants, and several studies have reported their application in wastewater treatment (Chen 2004; Anglada et al. 2009; Sirs and Brillas 2012; Brillas and Martnez-Huitle 2015; Fernandes et al. 2015). In particular, anodic oxidation (AO) has demonstrated its high potential for the degradation of persistent organic pollutants, especially when boron-doped diamond (BDD) anodes are used. This anode material presents exceptional properties and, when applied in electrochemical reactors, generates hydroxyl radicals that have a high oxidation potential and are non-selective oxidants, leading to the complete mineralization of the organic compounds (R) present in wastewaters (Eq. 1 and 2) (Brillas and Martnez-Huitle 2015).
BDD H2OBDD OH
H e 1
BDD OH RBDD CO2 H2O H e 2
However, the high cost of BDD electrodes and the energy...