02 Fakultät Bau- und Umweltingenieurwissenschaften
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3
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Item Open Access Batch studies of phosphonate and phosphate adsorption on granular ferric hydroxide (GFH) with membrane concentrate and its synthetic replicas(2020) Reinhardt, Tobias; Veizaga Campero, Adriana Noelia; Minke, Ralf; Schönberger, Harald; Rott, EduardPhosphonates are widely used as antiscalants for softening processes in drinking water treatment. To prevent eutrophication and accumulation in the sediment, it is desirable to remove them from the membrane concentrate before they are discharged into receiving water bodies. This study describes batch experiments with synthetic solutions and real membrane concentrate, both in the presence of and absence of granular ferric hydroxide (GFH), to better understand the influence of ions on phosphonate and phosphate adsorption. To this end, experiments were conducted with six different phosphonates, using different molar Ca:phosphonate ratios. The calcium already contained in the GFH plays an essential role in the elimination process, as it can be re-dissolved, and, therefore, increase the molar Ca:phosphonate ratio. (Hydrogen-)carbonate ions had a competitive effect on the adsorption of phosphonates and phosphate, whereas the influence of sulfate and nitrate ions was negligible. Up to pH 8, the presence of CaII had a positive effect on adsorption, probably due to the formation of ternary complexes. At pH > 8, increased removal was observed, with either direct precipitation of Ca:phosphonate complexes or the presence of inorganic precipitates of calcium, magnesium, and phosphate serving as adsorbents for the phosphorus compounds. In addition, the presence of (hydrogen-)carbonate ions resulted in precipitation of CaCO3 and/or dolomite, which also acted as adsorbents for the phosphorus compounds.Item Open Access Detoxification of pesticide-containing wastewater with FeIII, activated carbon and Fenton reagent and its control using three standardized bacterial inhibition tests(2017) Rott, Eduard; Pittmann, Timo; Wasielewski, Stephan; Kugele, Amélie; Minke, RalfDischarge of toxic industrial wastewaters into biological wastewater treatment plants may result in inhibition of activated sludge bacteria (ASB). In order to find an appropriate method of detoxification, the wastewater of a pesticide-processing plant in Vietnam was treated with three different methods (FeIII, powdered activated carbon (PAC), Fenton (FeII/H2O2)) analyzing the detoxification effect with the nitrification inhibition test (NIT), respiration inhibition test (RIT) and luminescent bacteria test (LBT). The heterotrophic ASB were much more resistant to the wastewater than the autotrophic nitrificants. The NIT turned out to be more suitable than the RIT since the NIT was less time-consuming and more reliable. In addition, the marine Aliivibrio fischeri were more sensitive than the nitrificants indicating that a lack of inhibition in the very practical and time-efficient LBT correlates with a lack of nitrification inhibition. With 95%, the Fenton method showed the highest efficiency regarding the chemical oxygen demand (COD) removal. Although similar COD removal (60–65%) was found for both the FeIII and the PAC method, the inhibitory effect of the wastewater was reduced much more strongly with PAC. Both the NIT and the LBT showed that the PAC and Fenton methods led to a similar reduction in the inhibitory effect.Item Open Access Influence of ammonium ions, organic load and flow rate on the UV/chlorine AOP applied to effluent of a wastewater treatment plant at pilot scale(2018) Rott, Eduard; Kuch, Bertram; Lange, Claudia; Richter, Philipp; Minke, RalfThis work investigates the influence of ammonium ions and the organic load (chemical oxygen demand (COD)) on the UV/chlorine AOP regarding the maintenance of free available chlorine (FAC) and elimination of 16 emerging contaminants (ECs) from wastewater treatment plant effluent (WWTE) at pilot scale (UV chamber at 0.4 kW). COD inhibited the FAC maintenance in the UV chamber influent at a ratio of 0.16 mg FAC per mg COD (kHOCl–COD = 182 M−1s−1). An increase in ammonium ion concentration led to a stoichiometric decrease of the FAC concentration in the UV chamber influent. Especially in cold seasons due to insufficient nitrification, the ammonium ion concentration in WWTE can become so high that it becomes impossible to achieve sufficiently high FAC concentrations in the UV chamber influent. For all ECs, the elimination effect by the UV/combined Cl2 AOP (UV/CC) was not significantly higher than that by sole UV treatment. Accordingly, the UV/chlorine AOP is very sensitive and loses its effectiveness drastically as soon as there is no FAC but only CC in the UV chamber influent. Therefore, within the electrical energy consumption range tested (0.13–1 kWh/m3), a stable EC elimination performance of the UV/chlorine AOP cannot be maintained throughout the year.Item Open Access Behavior of PBTC, HEDP, and aminophosphonates in the process of wastewater treatment(2019) Rott, Eduard; Happel, Oliver; Armbruster, Dominic; Minke, RalfTen times at intervals of 1–2 months, individual treatment stages of two wastewater treatment plants (WWTPs) were analyzed for the five quantitatively most widely used phosphonates. The total dissolved concentration of the investigated phosphonates in the influents was between 131 µg/L and 384 µg/L. The nitrogen-free phosphonates 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and 1-hydroxyethylidene(1,1-diphosphonic acid) (HEDP) accounted for an average proportion of 83–85%. Diethylenetriaminepenta(methylene phosphonic acid) (DTPMP) contributed with 13–14%, whereas aminotris(methylphosphonic acid) (ATMP) (≤15 µg/L) and ethylenediaminetetra(methylene phosphonic acid) (EDTMP) (≤11 µg/L) contents detected in the WWTP influents were comparatively low. The application of new analytical methods allowed the quantification of phosphonates in the solid fraction of the WWTP influents for the first time. High loads of phosphonates were determined (223–2555 mg/kg), indicating that 20%–80% of the phosphonates are present in the adsorbed state. The removal of total dissolved phosphonate by secondary clarification was between 69.7% and 92.4% (medians: 90.7% and 87.7%). In both WWTPs, HEDP (medians: 89.2% and 86.4%) was slightly better eliminated than PBTC (medians: 87.2% and 82.5%). In the sand filtration stage of a WWTP, the average removal was not further improved. In contrast, an additional removal of dissolved phosphonates could be achieved by activated carbon treatment (median: 96.4%). The proportion of phosphonate-P in the dissolved unreactive phosphorus fraction was consistently between 10% and 40% throughout all treatment stages.Item Open Access Application of natural clinoptilolite for ammonium removal from sludge water(2020) Wasielewski, Stephan; Rott, Eduard; Minke, Ralf; Steinmetz, HeidrunItem Open Access Influence of wastewater discharge on the occurrence of PBTC, HEDP, and aminophosphonates in sediment, suspended matter, and the aqueous phase of rivers(2020) Rott, Eduard; Happel, Oliver; Armbruster, Dominic; Minke, RalfSediment, suspended matter (SM), and water of a large river (Neckar; River1) and a small river (Körsch; River2) were analyzed for the phosphonates 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), 1-hydroxyethylidene (1,1-diphosphonic acid) (HEDP), aminotris (methylphosphonic acid) (ATMP), ethylenediaminetetra (methylene phosphonic acid) (EDTMP), and diethylenetriaminepenta (methylene phosphonic acid) (DTPMP). Ten samplings were performed at intervals of one to two months during one year, each covering the relevant matrices before and behind the discharge point of a wastewater treatment plant (WWTP). In River1, the total concentration of dissolved phosphonate did not change significantly (2.4–5.8 µg/L before vs. 2.5–6.6 µg/L behind WWTP; p = 0.9360). In River2, it increased significantly from <0.1–1.6 µg/L to 19–39 µg/L (p < 0.0001). Based on the median, the total phosphonate load in River1 sediment increased 1.9-fold (6.7–29.4 mg/kg before vs. 17.8–53.5 mg/kg behind WWTP; p = 0.0033) and in River2 by a factor of eight (1.8–5.0 mg/kg before vs. 18.1–51.4 mg/kg behind WWTP; p < 0.0001). This indicates that phosphonates discharged by WWTPs adsorb onto solid particles and accumulate in the sediment. In the case of River2, the SM load could reach values of 1000–1710 mg/kg behind the WWTP, presumably due to the introduction of insufficiently retained activated sludge particles of >2000 mg/kg phosphonate loads. In general, the nitrogen-free phosphonates PBTC and HEDP were most predominant in both dissolved and adsorbed form, of which HEDP had the highest adsorption affinity.Item Open Access Removal of emerging contaminants and estrogenic activity from wastewater treatment plant effluent with UV/chlorine and UV/H2O2 advanced oxidation treatment at pilot scale(2018) Rott, Eduard; Kuch, Bertram; Lange, Claudia; Richter, Philipp; Kugele, Amélie; Minke, RalfEffluent of a municipal wastewater treatment plant (WWTP) was treated on-site with the UV/chlorine (UV/HOCl) advanced oxidation process (AOP) using a pilot plant equipped with a medium pressure UV lamp with an adjustable performance of up to 1 kW. Results obtained from parallel experiments with the same pilot plant, where the state of the art UV/H2O2 AOP was applied, were compared regarding the removal of emerging contaminants (EC) and the formation of adsorbable organohalogens (AOX). Furthermore, the total estrogenic activity was measured in samples treated with the UV/chlorine AOP. At an energy consumption of 0.4 kWh/m3 (0.4 kW, 1 m3/h) and in a range of oxidant concentrations from 1 to 6 mg/L, the UV/chlorine AOP had a significantly higher EC removal yield than the UV/H2O2 AOP. With free available chlorine concentrations (FAC) in the UV chamber influent of at least 5 mg/L (11 mg/L of dosed Cl2), the total estrogenic activity could be reduced by at least 97%. To achieve a certain concentration of FAC in the UV chamber influent, double to triple the amount of dosed Cl2 was needed, resulting in AOX concentrations of up to 520 µg/L.Item Open Access Recovery of ammonium sulfate solution by regeneration of loaded clinoptilolite(2022) Wasielewski, Stephan; Rott, Eduard; Minke, Ralf; Steinmetz, HeidrunThe zeolite clinoptilolite (CLI) is known to be a very good ion exchanger, as it consists of a three-dimensional structure formed of AlO4- and SiO4 tetrahedral, which are connected by a common oxygen atom. The micropores formed by this structure (with free diameters in the range of 0.40 nm and 0.72 nm) are fine enough to allow cations and water molecules to enter and be exchanged. CLI is a suitable, inexpensive, and globally available material for removing ammonium from highly-concentrated wastewater and is proven to be selective in ammonium uptake and regeneration since no effect of the provenance of the ammonium (matrix-free NH4Cl solution or sludge water) could be found. However, regeneration of the clinoptilolite is necessary to recover the adsorbed ammonium for further use and restore its capability for ion exchange. Within this work, the method by which clinoptilolite, loaded with ammonium (q = 8.1-16.6 mg/g) from different sludge waters and ammonium chloride solution, can be regenerated to yield a stoichiometric ammonium sulfate solution (ASS), that could be used, e.g., as a fertilizer, was investigated. A regeneration solution containing Na2SO4 (0.25 n(Na2SO4)/n(NH4+ads)) with a varying NaOH ratio (0-2.14 n(NaOH)/n(NH4+ads)) was tested. To obtain a high ammonium concentration in the eluate, a large mass fraction ω of 284 g/kg of CLI in the regeneration solution was applied. The effects of different ammonium loads, different origins of the ammonium, and residual moisture on the necessary components of the regeneration solution, in which an ASS is obtained within a contact time of 10 min at 22 °C, were studied. A stoichiometric ASS from CLI loaded up to a maximum of 13.5 mg/g was obtained with a mixture of 0.25 n(Na2SO4)/n(NH4+ads) together with 0.8-1.0 n(NaOH)/n(NH4+ads) for dry CLI, and 0.75 n(NaOH)/n(NH4+ads) for CLI with residual moisture.