Charcoal powder for eliminating trace substances from sewage water

Abstract

The invention relates to finely ground charcoal powder, characterized in that the particle size (measured according to ISO 13320) is at least d50 < 10 μm, the specific surface area (measured according to ISO 9277) is at most 600 m2 / g, the trace-substance elimination capacity in at least 30 min of contact time is at least 15%, the SAC254 decrease in at least 30 min of contact time is at least 20%, and the global warming potential (GWP100, determined according to ISO 14040) is less than 1 Mg CO2 eq per Mg charcoal powder. The finely ground charcoal powder is used in sewage treatment for adsorption or elimination of trace substances.

Description

[0001]23-04-2024-37913301-HauP Po +-0013 PCT / DE2024 / 000029 Charcoal powder for the removal of trace substances. The present invention describes the use of finely ground charcoal powder with a very low greenhouse gas potential (GWP) for the removal of trace substances from pre-treated wastewater from sewage treatment plants. Residues of organic chemicals, such as pharmaceuticals, cleaning agents, rust inhibitors, pesticides, or similar micropollutants, enter municipal wastewater every day. Conventional sewage treatment plants can hardly eliminate such residues, which is why, according to the state of the art (EP 3 957 608 A1), these plants are retrofitted with activated carbon (AC) absorbers. The published patent application CH715008A2 discloses activated carbon in the form of granulated activated carbon (GAC) with a particle diameter typically in the range of 100 to 2000 pm or in the form of powdered activated carbon (PAC) with a particle diameter typically in the range of 3 to 100 pm.Despite the successful cleaning results, the use of GAC and PAH must be re-evaluated under the conditions of climate change. Activated carbons are predominantly made from fossil coal sources, such as lignite and hard coal. Bio-based activated carbons also on the market are made from coconut shells, bamboo or wood. Regardless of the raw material, activated carbons are produced in two process steps. In the first process step, coconut shells, bamboo or wood are pyrolytically degassed to form coal or coals. After cooling, an energy-intensive heating process, after which the coal is activated, takes place. During activation, the pore space, measured by the specific surface area according to BET (ISO 9277), increases from < 200 m2 to > 600 m2. Common activated carbons have specific surface areas of 900 - 2500 m. 2It is generally assumed that the adsorption capacity of AC increases with the specific surface area. Due to the complex thermal treatment and transport, coconut shell or bamboo charcoal from East Asia, hard coal from Australia or South America, activated carbons have a high GWP. According to Gu Cu, 2-04-2024-37S13301-HauPtP t- 0014 PCT / DE2024 / 000029 Bergman, Anderson, Alanya-Rosenbaum, cycle assessment of activated carbon from woody biomass", Wood and Fiber Science, 229-243), the GWP, considered over a period of 100 years (GWPioo), for AC from wood, if the synthesis gas from pyrolysis is used for activation, is 7.63 kg carbon dioxide equivalents (CO2 eq) per kilogram of AC and activated carbon from hard coal 18.28 kg CO2. eq / kg AK. Bayer (Bayer, Heuer, 2005). "Economical and ecological comparison of granular activated carbon (GAC) adsorber Water Res., 1719-28) state GWPioo of kg CO2 eq / kg GAC from hard coal.When using PAHs to remove trace substances in wastewater treatment plants, a rough guideline of 0.5 Mg PAH per 1,000 population units (PE) per year can be assumed. A wastewater treatment plant with 250,000 PE consumes 125 Mg PAH / year. This corresponds to a GWPioo of PAH from hard coal of 2,285 Mg CO2 eq / year. The present invention aims to significantly reduce the GWPioo compared to the state of the art by using finely ground, thermally activated charcoal powder with the same treatment performance, thus reducing the burden on the environment. Unexpectedly, it was found that ground charcoal powder with particle sizes of 90% 10 pm (percentile d90 < 10 pm), preferably with a particle size d50 < 10 pm (measured with Malvern Mastersizer according to ISO 13320), preferably a powder from coal from a wood gasification plant, particularly preferably powder from a wood gasification plant, the raw material in particular softwood pellets wood gasification wood pellets coal, HHPK), but a low specific surface area (according to ISO 9277) of only 400 m.2Use as an alternative to PAHs with approximately the same efficiency for trace substance removal. The table shows a comparison of the UV light absorption of HHPK d90 < 10 pm with five commercial activated carbon powders made from coconut shells or hard coal. The carbons were stirred into 5 mg, 10 mg, and 20 mg of wastewater from a wastewater treatment plant at 100 rpm for 30 minutes. An aliquot was then measured at 0.45 pm and the absorption at 254 nm. Trace substance absorption is a sum parameter measured by UV light absorption. At a measuring wavelength of 254 nm, the spectral absorption coefficient is converted to extinction per meter, 25-04-2024-37913301-HauP - 00iS PCT / DE2024 / 000029 Result information SAK254 In the SAK254, organic carbons (DOC) are measured, but it is a good measure of the contamination of water with organic Tab.Addition of coal powder wastewater to the 30 min stirring 100 revolutions / min, over 0.45 pm and determination of the spectral absorption coefficient 254 nm extinction / m (SAK254 [m Ref. = Reference. As can be seen from the table, HHPK d90 < 10 pm absorbs the trace substances significantly better than PAH B from PAH AC from coconut and PAH D from hard coal (difference of 9.9%), and 85% compared to PAH from hard coal (difference of 11.6%). In wastewater treatment plants, various concepts for the use of activated carbons are used with regard to application sites and residence times. A common method involves the addition of water-dispersed carbon to the treatment stage with a residence time of 5,600 min, preferably 20,120 min, and particularly preferably 30,600 min.Since trace substances absorbed on the coal and the coal itself may remain in the wastewater, Fe) or aluminum salts, ( For capacity reasons, the shortest possible residence time of the coal in the water should be aimed for, which in practice leads to residence times of 60 min. Table 2 shows the HHPK d90 < 10 pm in comparison to two PAHs used in practice (PAH PAH G) using the SAK254 and the elimination of the KomS B 2F:7s-04-2024-37S 3301-HauP i 0016 PCT / DE2024 / 000029 Since the SAK254 is only a non-specific sum parameter in real wastewater, trace substance elimination was investigated with 7 model substances which are considered representative of the trace substance contamination of wastewater. The 7 model substances were selected by the Baden-Württemberg Competence Center for Trace Substances (KomS) and are B The concentration of the coal was 20 The trace substance elimination is Total parameter of dissolved organic carbon (DOC) below 0.45 pm.KomS 1H-benzotriazole, 4H+5H benzotriazole, metoprolol, carbamazepine, diclofenac, rbesartan, hydrochlorothiazide Tab.2 of the percentage reduction of SAK254 and trace substance elimination (KomS B) dependence of the contact time of the carbon powder (20 in water. As can be seen from Table 2, both the SAK254 and the elimination of the substances from the KomS B are higher than those of the comparison PAH F and G after the first 30 min of contact time (HHPK d90 < 10 pm). After 60 min, HHPK d90 < 10 pm and PAH G are equivalent, while PAH F is still below this. Only after 240 min do the PAH FG adsorb and eliminate better (HHPK d90 < 10 pm). Unexpectedly, it was shown that a somewhat coarser particle distribution of the HHPK with particle sizes d50 < 10 pm also results in a high elimination of trace substances or a reduction in SAC254, as shown in Table 3. A somewhat coarser 2S-04-2024-37913301-HauP tPos 0017 PCT / DE2024 / 000029 particle distribution results in both a higher grinding throughput and lower energy consumption, and is therefore desirable. The percentage reductions in SAC254 and trace substance eliminations in Tables 2 and 3 are comparable, as the measured values ​​in Table 2 were obtained using the test substances of the B, and the measured values ​​in Table 3 were obtained using actual wastewater treatment plant water.Tab.3 of the percentage reduction of SAK254 and the trace substance elimination dependence of the contact time of the coal powder (20 mg / I) in the wastewater treatment plant water. However, the effects of the coals are comparable with each other. HHPK d50 < 10 pm (Table 1) in the period of 60 min for SAK254 with 34.3% higher values ​​for PAH F with 19.7% and PAH G with 28.5%. The trace substance eliminations are comparable, with HHPK d50 < 10 pm after 60 min 22.4%, while PAH F only 12.1% and PAH G 17.2%. Even after 1440 min (24) SAK254 has a reduction of 44.5%, while PAH F is at 33.6%. 1 / 4less, and PAH G with 48.9%, 1 / 10 more reduction. The order of trace substance elimination is maintained. After 24 h, the trace substance elimination of HHPK d50 < 10 pm was 29.3%. The values ​​of PAH F were just below 22.4%, while PAH G were just above 36.2%. In addition to the laboratory-scale stirring tests, tests were carried out at a municipal wastewater treatment plant with HHPK d90 < 10 pm and PAH H, whereby PAH H is a PAH from hard coal (Table 5). The information on the water quality parameters in Table 5 refers to the measurements of HHPK d90 < 10 pm. In addition to flocculation, the coal particles and trace substances adhering to them were removed from the purified water through an ultrafiltration membrane. 2S-04-2024-378i 3301-HauP tPos t-0018 PCT / DE2024 / 000029 The coal addition the effluent of the secondary clarifier and upstream of the ultrafiltration membrane.A coal powder suspension was fed into the inlet pipe in front of the membrane. The concentration in the wastewater was 20. The coal powder suspension was mixed with fresh water (100) and a pre-weighed amount of coal (kg), which corresponds to a concentration of 10. The flocculant dosage was added in front of the ultrafiltration membrane. Tab. 4 Specification of HHPK d90 < 10 pm and PAH H. To assess the water quality after the carbon powder treatment, the chemical oxygen demand (COD), the DOC, the total phosphorus content (PO4), the orthophosphate content (PO4), the SAC254 and the percentage removal of trace substances were determined. The values ​​are shown in Table 5. Table 5 Water quality parameters after treatment with conventional powdered activated carbon (PAH H) on May 12, 2020 and May 17, 2020 as well as with HHPK d90 < 10 pm on November 18, 2021, November 23, 2021 and November 24, 2021. The CSB in both test periods (May 2020 and November 2021) was constant on average 21. The DOC, however, was when using HHPK 23-04-2024-37813301-Ham Pos - 0019 PCT / DE2024 / 000029 d90 < 10 pm with an average of 7.3 mg / l slightly higher use of PAH H with 6.4 The total phosphate and orthophosphate contents of the measurements in November 2021 are slightly higher than the measurement on May 17, 2020, but significantly below the measurement on May 12, 2020. The SAK254 values ​​were significantly higher when using HHPK d90 < 10 pm with an average of 17.4 mg / l when using PAH H with an average of 11.8 mg / l Thus, the measurements with HHPK d90 < 10 pm are based on slightly more heavily contaminated wastewater. Compared to a PAH HHPK d90 < 10 pm conventionally used in wastewater treatment plants with advanced treatment stages for trace substance removal, the percentage of trace substance removal with PAH H is just under 44%. HHPK d90 < 10 pm thus represents a 35% greater reduction in trace substances compared to PAH H.The GWP100 of HHPK < 10 pm (collectively HHPK d90 and d50 < 10 pm) is composed of individual GWPioo, such as input loads, emissions from HHPK production, grinding to HHPK < 10 pm and the output load, each based on one ton (Mg). A flat rate distance of 330 km was assumed for the input loads. The GWPioo associated with this distance was obtained from the German Freight Forwarders' Association and estimated at 0.08 Mg CO2. Emissions from HHPK production are considered emissions from the pyrolytic conversion of biofuels, which do not produce greenhouse gases; however, energy expenditures in the upstream chain of 0.16 Mg CO2 must be taken into account (Memmler, Schrempf, Hermann, Schneider, Pabst, Dreher, 2014). Climate Change 29 / 2014, Emissions balance of renewable energy sources - Determination of avoided emissions in 2013. Dessau-Roßlau: Federal Environment Agency).For the grinding of mills operated with a mix of electricity from the municipal utilities and their own photovoltaics, 0.01 Mg CO2 is estimated. For the outgoing freight, an average distance of 415 km is assumed with a CO2 load of Mg (German Freight Forwarders and Association). Total for HHPK < 10 pm a GWPioo of 0.35 Mg CO2 Mg HHPK < 10 pm. HHPK < 10 pm saves compared to AK from 7.28 Mg CO2 eq / Mg AK and 17.93 Mg CO2 eq / Mg AK from hard coal. Since the emission of CO2 is now priced in summer 2022 it was according to EEX (price development) on average 85 E / Mg, this results in additional, Hau 2S-04-2024-37913301-HAuP 0020 PCT / DE2024 / 000029 significant economic advantages of several 100 E / Mg HHPK < 10 pm compared to PAH from wood but especially compared to PAHs from resources.

Claims

Hau2S-04-2024-37S 13301—HauPtPos 0022 PCT / DE2024 / 000029 Patent claims Finely ground charcoal powder, characterized in that particle size (measured according to ISO 13320) at least d50 < 10 pm, specific surface area (measured according to ISO 9277) at most 600 m2 Trace substance elimination capacity at least 30 min contact time at least 15%, the SAK254 reduction at least 30 min contact time at least 20% and the greenhouse gas potential (GWPioo, according to ISO 14040) less than Mg CO2 eq per Mg charcoal powder Charcoal powder according to claim characterized in that particle size (measured according to ISO 13320) d90 < 10 pm Charcoal powder according to the claims and characterized in that the charcoal is made from softwood Charcoal powder according to the claims and characterized in that the coal from wood pellets is charcoal powder according to the claims and characterized in that the charcoal from a wood gasification plant is charcoal powder according to the claims 5 characterized in thatthat its greenhouse gas potential GWPioo is less than 0.5 Mg CO2eq per Mg charcoal powder. Use of a charcoal powder according to claims 6 in wastewater treatment, characterized in that the charcoal powder, determined according to SAK254, contains at least 20%, preferably at least 40% and particularly preferably at least 60% of the trace substances contained in the wastewater. Use of a charcoal powder in wastewater treatment according to claims, characterized in that the charcoal powder, determined, 2S-04-2024-37913301-HauP + 0023 PCT / DE2024 / 000029 according to DOC, at least 15%, preferably at least 30% and particularly preferably at least 45% of the trace substances contained in the wastewater. Use of a charcoal powder according to claims 7 and characterized in that the charcoal powder concentrations of 20 50, preferably of 10 20 mg / l and particularly preferably of 3 10 mg / l wastewater are used for trace substance adsorption or elimination. Process for wastewater treatment, to which the charcoal powder according to claims 9 is introduced into the wastewater and before its precipitation is adsorbed for at least 5 minutes, preferably at least 20 minutes and particularly preferably at least 30 minutes for trace substance adsorption or elimination. Process for wastewater treatment according to claim 7, characterized in that the charcoal powder concentrations of 20 50, preferably of 10 20 mg / l and particularly preferably of 3 10 mg / l wastewater used for trace substance adsorption or elimination

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