PHOSPHORUS FLOWS IN GERMAN SEWAGE SLUDGE ASHES AND POTENTIAL RECOVERY TECHNOLOGIES

Transcription

1 PHOSPHORUS FLOWS IN GERMAN SEWAGE SLUDGE ASHES AND POTENTIAL RECOVERY TECHNOLOGIES Christian Adam, Oliver Krüger, Hannes Herzel Mining the Technosphere 2015, Vienna University of Technology 1

2 Phosphorus Flows 2

3 Phosphorus in German waste water Waste water treatment in Germany: 9,600 waste water treatment plants 10 billion m 3 /a wastewater containing ~73,000 t/a P ~1.8 million tons sewage sludge containing ~65,000 t/a P Agriculture in Germany: Ca. 560,000 t/a P taken up by plants and removed from soil by harvest Most of P returned to soil in form of farm fertilisers Ca. 140,000 t/a P applied in form of mineral fertilisers based on phosphate rock Relevant amount of P in relation to fertilizer consumption Part of it already recycled in form of sewage sludge application on field 3

4 Pathways of German sewage sludge Source: DESTATIS 4

5 What does thermal treatment mean? Sewage sludge ash concentration of P Lehrmann (2012) 5

6 Monitoring of German Sewage Sludge Ashes Project financed by the German Ministry for the Environment (2012/2013) UFOPLAN FKZ of 26 mono-incineration facilities Monthly sampling 252 samples Municipal, industrial and mixed sludges Amount of ash~ 300,000 t/a Collection quota: >97 % 6

7 Main components of sewage sludge ash Element [%] Min Max Median Al Ca Fe K < Mg Na P S Si Ti

8 P mass fractions in ash of the different facilities mono incineration facilities sorted by P mass fraction Median mass fraction (%) Ash (kt/a) P (kt/a) Substi -tution (%)* total municipal mixed industrial * Theoretical potential for substitution of 140 kt P in P-rock based fertilizers in Germany industrial mixed municipal Smart sludge incineration Separation of industrial and municipal sludge before incineration 8

9 P output of the 24 mono-incineration facilities Amount of ash (t/a) Aschemenge Aschemenge [t/a] Anlage facility number Phosphorgehalt P mass fraction (%) Phosphormenge [t/a] Amount of Phosphormenge P (t/a) Phosphorgehalt [%] Anlage facility number facility number Anlage 9

10 P-bioavailability of sewage sludge ash Phosphorus soluble in neutral ammonium citrate (P NAC ) [%] Min Max Median P NAC bioabailability of P in sewage sludge ashes is poor P-bearing mineral phases: whitlockite Ca 3 (PO 4 ) 2 aluminium phosphate AlPO 4 Peplinski et al. (2011) 10

11 Anteil [mg/kg] mass fraction Heavy metals in sewage sludge ash Ni Pb As Element Smart sludge incineration to decrease heavy metal content limit value fertilizer ordinance (DüMV) 11

12 Variability of Pb mass fractions during 1 year Pb [mg/kg] Limit German Fertilizer Ordinance Sep Okt Nov Dez Jan Feb Mär Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan Feb Mär Apr Mai Jun Jul Aug Sep Okt Monat

13 Variability of Hg mass fractions during 1 year Hg [mg/kg] Limit German Fertilizer Ordinance Sep Okt Nov Dez Jan Feb Mär Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan Feb Mär Apr Mai Jun Jul Aug Sep Okt Monat 13

14 Sewage Sludge Ash and fertilizer ordinance (DüMV) SSA generally permitted as fertilizer, but some ashes show heavy metal mass fractions higher than limit values of the fertilizer ordinance => further treatment necessary Above limit of DüMV Ni Pb As Hg Cd total Facilities Ash [t/a] 204, ,244 19, ,485 83, ,244 P [t/a] 10,043 9,437 1,863 6,185 3,807 12,718 14

15 Sewage Sludge Ash compared to conventional fertilizers SSA contains less Cd and U compared to P-rock or TSP: Cadmium Uranium P-rock 13 mg/kg 89 mg/kg 46 mg Cd/kg P 2 O mg U/kg P 2 O 5 TSP 24 mg/kg 125 mg/kg 54 mg Cd/kg P 2 O mg U/kg P 2 O 5 Ash 3 mg/kg 23 mg Cd/kg P 2 O 5 6 mg/kg 40 mg U/kg P 2 O 5 Source: Kratz et al.,

16 Pathways of German sewage sludge ashes (from mono-incineration) Construction (7 Facilities) Mine filling (9 Facilities) Copper mill (1 Facility) Landfilling (4 Facilities) Fertilizer (1 Facility) 19,972 t (7%) 104,167 t (35%) 84,139 t (29%) 11,500 t (4%) Krüger and Adam (2012) Results of own survey 74,013 t (25%) 16

17 Recovery Technologies 17

18 Processes for P-recovery from waste water EU FP 7 project Full-scale Demo Lab/Pilot

19 Processes for sewage sludge and ash treatment Petzet, S., Peplinski, B. and Cornel, P., On wet chemical phosphorus recovery from sewage sludge ash by acidic or 1.0 t ash alkaline leaching and an optimized combination of both. Water Res. 46, t wet residue (67% water) ~0.92 t dry matter 9.4 t water 0.6 t H 2 SO t NaOH (100% NaOH) 12w-% P 4.0 Mg Al-, Fe-, Ca-P product (80% water, 20% SO 3, 10% Na 2 O) ~0.8 t dry product 4.8 t waste water Modified from:christian Schaum, PhD Thesis, TU Darmstadt,

20 Leachphos, acidic ash leaching Pilot study by BSH (40 t ash) BSH Umweltservice Medium scale pilot plant by FHNW 20

21 EcoPhos, acidic ash leaching ESPC 2; De Ruiter, 2015 (EcoPhos was not a participant in P-REX but took part in the LCA study) 21

22 Mephrec, metallurgical treatment of sludge and/or ash Pre-Pilot trial t briquettes Pilot plant planned in Nuremberg, Germany: 0.5 t/h briquette 1000 h operation time 22

23 ASH DEC, thermochemical ash treatment (Removal of As, Cd, Hg, Pb, Zn) Pilot plant t ash (MgCl 2 -additive) CaNaPO 4 (Sewage sludge) Pilot study 2014 in P-REX 4 t ash (Na 2 SO 4 -additive) 23

24 ASH DEC process (BAM/Outotec) 4 day industrial production of 2 t product for P-fertilizer No removal of Cu, Cr, Ni, U (Only dilution) 2. Removal (via off-gas): As 61% Cd 80% Hg 68% Pb 39% Zn 9% Ash Product without removal (calculated) Product (measured) Limit German fertilizer ordinance (Outotec / Herzel et al. 2015) 24

25 recycling products tested in pot experiments Sewage sludge Precipitation-/Crystallisation Sludge 1 Sludge 2 Sludge 3 liquid dewatered Fe-rich, dewatered Cryst 1 Cryst 2 Cryst 4 Products from ash treatment Raw ash BAM/MgCl 2 BAM/Na-variant BSH LeachPhos Therm 1 Therm 2 Therm 3 Therm 4 Therm 5 Reference TSP Phosphorus Fertilizer from Sewage Sludge Ashes by thermochemical treatment - Benefits and Challenges

26 Dry Matter Yield (g/plant) Results of greenhouse pot experiments (DMY maize) sludges struvites ash products Soil 1 (ph 7.1) Soil 2 (ph 4.9) BAM MgCl 2 BAM Na-Var. BSH Leach Phos Raw ash P-product 26

27 LCA results Impacts Credits P recovered [%]

28 Process cost Liquor Sludge Ash 28

29 Summary Sewage sludge ash: High P mass fraction (up to 13 %) and high recovery potential Challenges: 1. heavy metals 2. P-bioavailability P-recovery from ash Technologies can recover 70-90% of P Products have a good fertilization performance The processes can have positive effects on the environment 0-3 transition cost per capita and year (+2 if additional monoinc. required) 29

30 Thank you for your attention Christian Adam Bundesanstalt für Materialforschung und prüfung (BAM) Division 4.4 Thermochemical Residues Treatment and Resource Recovery Recovery potential of German sewage sludge ash. Krüger, O., Adam, C. (2015) Waste Management Complete survey of German sewage sludge ash. Krüger, O., Grabner, A., Adam, C. (2014) Environmental Science and Technology. Sewage sludge ash a promising secondary phosphorus source for fertilizer production. Herzel, H., Krüger, O., Hermann, L., Adam, C. (2015) Science of the Total Environment Thermochemical treatment of sewage sludge ash with sodium salt additives for phosphorus fertilizer production - analysis of underlying chemical reactions. Stemann, J., Peplinski, B., Adam, C. (2015) Waste Management Comparative review of ash processes. P-REX deliverable D4.1. Herzel, H.; Adam, C.; Hermann, L.; Mallon, J.; Schaaf, M.; Eicher, N.; Stemann J. (2015):, available for download here: 30