E. Rott, R. Minke, H. Steinmetz
Jun 1, 2017
Citations
2
Influential Citations
57
Citations
Journal
Journal of water process engineering
Abstract
Abstract Phosphonates are to be removed from industrial wastewater before they reach municipal wastewater treatment plants or surface waters. Industrial wastewaters contaminated with the phosphonates 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), 1-hydroxyethylidene-(1,1-diphosphonic acid) (HEDP), nitrilotrimethylphosphonic acid (NTMP), ethylenediamine tetra(methylene phosphonic acid) (EDTMP) and diethylenetriamine penta(methylene phosphonic acid) (DTPMP) can be subdivided into: (1) mostly clear concentrates with a high water hardness, and (2) organically polluted wastewaters, for instance from the paper and textile industries. Our own flocculation experiments with FeIII and AlIII salts showed that, at a pH of 7.5, the adsorption affinity of polyphosphonates onto iron hydroxides and aluminum hydroxides significantly decreases with an increasing number of C-P bonds (HEDP > NTMP > EDTMP > DTPMP). In comparison to pure water spiked with phosphonates, the total P removal from concentrates occurred at similar and even lower flocculant dosage concentrations (s = 4–8) (s is the molar ratio of dosed metal concentration to total P concentration in the raw sample). In organically polluted industrial wastewaters, the formation of flocks, and therefore the total P decrease, only occurred after exceeding a certain flocculant concentration, which varied strongly depending on the wastewater type (s = 0.6–86). Below that concentration, the flocculant underwent complexation, and no elimination could be observed. For most of the wastewaters, the required s values for at least 80% total P decrease were very similar for both FeIII and AlIII. Furthermore, Ca(OH)2 as flocculant turned out to be an effective tool for total P removal and simultaneous softening of calcareous concentrates.