University of Stuttgart, Germany
Title: Organophosphonates: Environmental problems related to them and possible solutions for their elimination from industrial wastewater
Biography: Eduard Rott
Organophosphonates - mainly PBTC, HEDP, NTMP, EDTMP and DTPMP - are increasingly gaining attention of environmental authorities and scientists. These compounds are used in a wide range of industrial and household applications due to their excellent complexing properties. Organophosphonates are associated with various environmental issues. For example, phosphate, which has an eutrophication effect on water bodies, can be formed by their abiotic degradation. In addition, they are associated with heavy metal remobilization in waters, make it more difficult to comply with strict P discharge targets in wastewater treatment plants (WWTPs), and in individual cases interfere with the operation of WWTPs due to complex formation. It is estimated that in 2012, with a consumption of 49,000 t/a in Europe, organophosphonates were discharged at 9000–18,600 t/a into European waters via inadequately purified industrial wastewater and municipal WWTPs. The elimination of organophosphonates specifically from industrial wastewaters is therefore strongly recommended. Wastewater contaminated with organophosphonates can be roughly divided into two categories. On the one hand, there are concentrates, e.g. from membrane filtration and cooling water treatment, where phosphonates are used as antiscalants and hardness stabilizers. On the other hand, there are mainly organically contaminated wastewaters containing phosphonates from industrial cleaning agents or, e.g., from paper and textile industries, where phosphonates are used as bleach stabilizers. This wide variety of possible wastewater matrixes requires different approaches in terms of the objective to eliminate organophosphonates from industrial wastewater. The presentation will compare different wastewater treatment processes (precipitation/flocculation with FeIII or Ca(OH)2, (photo-)Fenton, UV/FeII, filtration) and will present the effects of the wastewater matrix on these processes. For example, the presence of CaII promotes the adsorption of phosphonates on iron hydroxides. Furthermore, organophosphonates can impede the precipitation of iron hydroxides due to their complexing properties.