Verwijdering van organische microverontreinigingen uit huishoudelijk afvalwater, waaronder medicijnresten, staat sterk in de belangstelling om de oppervlaktewater kwaliteit te verbeteren, de drinkwaterbronnen te beschermen en te voldoen aan toekomstige EU richtlijnen. In minder dan vijf jaar is AdOx, een technologie waarin adsorptie en oxidatie word en gecombineerd, ontwikkeld tot een veelbelovende techniek. Ten opzichte van referentietechnieken zijn de CO2-voetafdruk klein en de kosten laag. De Nederlandse richtlijn van 70% verwijdering wordt gehaald. Ondanks het gebruik van ozon resulteert AdOx niet in bromaat vorming en oxidatiebijproducten in het behandelde afvalwater. Er is nog veel ruimte voor verdere optimalisatie.@en

Organic micropollutants (OMPs) that occur in the aquatic environment at trace levels are emerging concerns to society. Domestic wastewater is an important source. OMPs end up in surface water and groundwater via conventional municipal wastewater treatment plants (WWTPs), penetrating drinking water. Comprising pharmaceuticals, personal care products, pesticides, industrial chemicals, and other compounds, OMPs are persistent in water and can lead to adverse effects on human health under longterm exposure. As WWTPs are not designed to remove OMPs, various post-treatment technologies have been developed to remove OMPs from wastewater effluents over the last decades, including activated carbon adsorption, ozonation, and membrane filtration. However, the performance of these technologies is significantly influenced by natural organic matter (NOM). In the combined application of ozonation and activated carbon adsorption, the operational costs and the environmental impact are relatively high because of the off-site thermal treatment of the exhausted carbon. The AdOx technology aims to establish a new barrier by applying sequential adsorption and oxidation to remove OMPs from municipal wastewater effectively. As an alternative adsorbent for activated carbon, zeolite possesses uniform pores (0.6-1.0 nm) that appropriately match the molecules of OMPs. This uniform framework can potentially exclude the large molecules of most NOM fractions in wastewater. This innovative technology, selective adsorption of OMPs on zeolite granules followed by on-site ozone-based regeneration of the granules loaded with OMPs, can lead to the next generation of OMPs removal, characterized by high removal efficiencies, low costs, and low environmental impacts....@en

AdOx is een combinatie van een adsorptieproces en een oxidatietechniek. Een veelbelovende technologie om medicijnresten uit afvalwater te halen. En winnaar van de Waterinnovatieprijs 2021, categorie Gezond Water en Gezonde Bodem.@en

Organic micropollutants (OMPs) that occur in the aquatic environment are an emerging concern. Adsorption by granular zeolites and regenerating exhausted zeolites by gaseous ozone is an innovative and advanced treatment technology for removing OMPs from wastewater treatment plant (WWTP) effluent. In this study, WWTP effluent spiked with eleven OMPs at 4–5 µg/L was treated by this combined technology, which included five steps in each cycle. The five steps comprised 1) selective adsorption of OMPs from WWTP effluent for five days by a zeolite granules fixed-bed column, 2) pre-backwash of the column, 3) drying of the column, 4) in-situ regeneration of the column with gaseous ozone 5) post-backwash of the column. The removal efficiency of eight OMPs (sotalol, metoprolol, propranolol, trimethoprim, clarithromycin, carbamazepine, methyl-benzotriazole, and benzotriazole) reached between 70 % and 100 % in six cycles. The adsorption of sulfamethoxazole and diclofenac was less favourable. In each cycle, less than 8 % of dissolved organic carbon (DOC) was removed from the WWTP effluent. The effect of the natural organic matter (NOM) on the adsorption of OMPs was negligible. Ozone consumption during regeneration was reduced by around 70 % by increasing pre-backwash duration from 30 min to 1 h. Ozonation directly with ozone gas can effectively regenerate the zeolite granules in the column under low ozone consumption.@en

Continuous development of industry and civilization has led to changes in composition, texture and toxicity of waste water due to the wide range of pollutants being present. Considering that the conventional wastewater treatment methods are insufficient for removing micropollutants and nutrients to a high level, other, alternative, treatment methods should be used to polish wastewater treatment plant effluents. In this study we developed an alternative, polishing concept for removal of ammonium and micropollutants that could potentially be incorporated in existing wastewater treatment plants. We demonstrated a method to use high silica MOR zeolite granules as an adsorbent for simultaneous removal of the micropollutant sulfamethoxazole (SMX) and ammonium (NH4+) ions from aqueous solutions. At an initial NH4+ concentration of 10 mg/L the high silica zeolite mordenite (MOR) granules removed 0.42 mg/g of NH4+, similar to the removal obtained by commonly used natural zeolite Zeolita (0.44 mg/g). However, at higher NH4+ concentrations the Zeolita performed better. In addition, the Langmuir isotherm model showed a higher maximum adsorption capacity of Zeolita (qmax, 4.08 mg/g), which was about two times higher than that of MOR (2.11). The adsorption capacity of MOR towards SMX, at both low (2 µg/L) and high (50 mg/L) initial concentrations, was high and even increased in the presence of NH4+ ions. The used adsorbent could be regenerated with ozone and reused in consecutive adsorption–regeneration cycles with marginal decrease in the total adsorption capacity.@en

Removal of contaminants of emerging concern (CECs) from municipal wastewater is becoming more and more important. On-site regeneration of exhausted adsorbents can be the key to practical applications. In this study, ozone-based regeneration of granular zeolites loaded with acetaminophen (ACE) was investigated. The adsorption capacity of ACE was 90 mg/g. After adsorption and breakthrough in column tests, granular zeolites were drained and dried for regeneration. Water content in granules is the main factor that limits the regeneration performance by affecting the gaseous ozone transfer rate. Ozone-based regeneration of fully dried granular zeolites (0% water content) is the most efficient, whereas fully wet granules (40% water content) have poor regeneration efficiency. Various ozone concentrations and gas flow rates were applied. With the same total mass of ozone dosed (900 mg), the regeneration efficiency increased by increasing the ozonation duration up to 50 min. The longer the regeneration time, the deeper the gaseous ozone can diffuse into the inner pores of zeolites to decompose the adsorbed ACE. The effect of gaseous ozone on the adsorption capacity of zeolites and the effect of the intermediates accumulation on the long-term adsorption capacity recovery rate were also investigated. It was found that gaseous ozone did not influence the adsorption of ACE on zeolites. The adsorption capacity of ACE decreased 7% after three adsorption-regeneration cycles. This can be explained by the accumulation of undissolved intermediate breakdown products adsorbed on the granules.@en

Advanced technologies to remove organic micropollutants (OMPs) from municipal wastewater have gained much attention over the last decades. Adsorption by zeolites is one of these technologies. In this study, the regeneration performance of well-tailored granular zeolites loaded with OMPs was evaluated. The selected OMPs were categorized into three groups due to the adsorption performance: high, medium and low adsorbance. Gaseous ozone was directly applied to regenerate dried zeolite granules at an ozone concentration of 30 mg/L and a gas flow rate of 0.2 L/min (0.04 m/s). For the high and medium adsorbing OMPs, 45 min of ozonation was long enough to fully restore their adsorption capacity. For the low adsorbing OMPs, the regeneration efficiency reached 60% after 60 min of ozonation. Interestingly, their recovered adsorption capacities firstly decreased and subsequently increased along with the ozonation duration. The dramatically decrease was most probably due to the presence of the transformation products generated from the ozonation of some selected OMPs. In seven sequential adsorption-regeneration cycles, the adsorption capacity for 75% of the selected OMPs was fully recovered at an ozonation duration of 60 min in each regeneration. The assumed accumulation of the ozonation transformation products only influenced the adsorption of low adsorbing OMPs in 7 cycles.@en