02.10.2015 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
Phosphorus Flows 2
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
Pathways of German sewage sludge Source: DESTATIS 4
What does thermal treatment mean? Sewage sludge ash concentration of P Lehrmann (2012) 5
Monitoring of German Sewage Sludge Ashes Project financed by the German Ministry for the Environment (2012/2013) UFOPLAN FKZ 3711 33 321 24 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
Main components of sewage sludge ash Element [%] Min Max Median Al 0.7 20.2 5.2 4.8 Ca 6.1 37.8 13.8 10.5 Fe 1.8 20.3 9.9 9.5 K <0.006 1.7 0.9 0.9 Mg 0.3 3.9 1.4 1.3 Na 0.2 2.6 0.7 0.6 P 1.5 13.1 7.3 7.9 S 0.3 6.9 1.5 1.0 Si 2.4 23.7 12.1 12.1 Ti 0.1 1.5 0.4 0.4 7
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 7.9 300.1 18.8 13.4 municipal 9.1 122.2 10.9 7.8 mixed 4.8 155.9 7.3 5.2 industrial 2.3 22.0 0.6 0.4 * 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
P output of the 24 mono-incineration facilities 50000 Amount of ash (t/a) Aschemenge Aschemenge [t/a] 40000 30000 20000 10000 0 12 10 12 7 22 21 17 23 2 16 13 15 9 5 8 Anlage facility number 14 25 19 3 11 4 6 20 26 1 Phosphorgehalt P mass fraction (%) Phosphormenge [t/a] 2250 2000 1750 1500 1250 1000 750 500 Amount of Phosphormenge P (t/a) 8 6 4 2 0 12 7 Phosphorgehalt [%] 22 21 17 23 2 16 13 15 8 14 25 19 3 11 4 6 20 26 1 9 5 250 0 12 7 22 21 17 23 9 5 2 16 13 15 8 14 25 19 3 11 4 6 20 26 1 Anlage facility number facility number Anlage 9
P-bioavailability of sewage sludge ash Phosphorus soluble in neutral ammonium citrate (P NAC ) [%] Min Max Median P NAC 10.2 82.6 32.4 26.2 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
Anteil [mg/kg] mass fraction Heavy metals in sewage sludge ash 450 400 350 300 250 200 150 100 50 0 Ni Pb As Element 20 23 12 6 21 22 3 5 7 19 1 18 25 26 16 17 14 11 15 9 4 2 8 13 Smart sludge incineration to decrease heavy metal content limit value fertilizer ordinance (DüMV) 11
Variability of Pb mass fractions during 1 year Pb [mg/kg] 500 400 300 200 100 0 Limit German Fertilizer Ordinance 2011 2013 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 1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 19 22 25 26 12
Variability of Hg mass fractions during 1 year Hg [mg/kg] 4 3 2 1 Limit German Fertilizer Ordinance 2 4 5 7 9 11 12 13 14 15 17 19 25 26 0 2011 2013 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
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 10 8 1 5 2 13 Ash [t/a] 204,564 167,244 19,972 114,485 83,000 233,244 P [t/a] 10,043 9,437 1,863 6,185 3,807 12,718 14
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 5 309 mg U/kg P 2 O 5 TSP 24 mg/kg 125 mg/kg 54 mg Cd/kg P 2 O 5 275 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., 2015 15
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
Recovery Technologies 17
Processes for P-recovery from waste water EU FP 7 project 2012-2015 www.p-rex.eu Full-scale Demo Lab/Pilot
Processes for sewage sludge and ash treatment Petzet, S., Peplinski, B. and Cornel, P., 2012. 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, 3769-3780. 2.8 t wet residue (67% water) ~0.92 t dry matter 9.4 t water 0.6 t H 2 SO 4 0.3 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, 2007 19
Leachphos, acidic ash leaching Pilot study 2012-13 by BSH (40 t ash) BSH Umweltservice Medium scale pilot plant by FHNW 20
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
Mephrec, metallurgical treatment of sludge and/or ash Pre-Pilot trial 2008 1.5 t briquettes Pilot plant planned in Nuremberg, Germany: 0.5 t/h briquette 1000 h operation time 22
ASH DEC, thermochemical ash treatment (Removal of As, Cd, Hg, Pb, Zn) Pilot plant 2008-2010 1500 t ash (MgCl 2 -additive) CaNaPO 4 (Sewage sludge) Pilot study 2014 in P-REX 4 t ash (Na 2 SO 4 -additive) 23
ASH DEC process (BAM/Outotec) 4 day industrial production of 2 t product for P-fertilizer 1. 2. 1. 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
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 09.09.2015 Phosphorus Fertilizer from Sewage Sludge Ashes by thermochemical treatment - Benefits and Challenges
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
LCA results Impacts Credits P recovered [%] 70 81 81 81 97 97 98 27
Process cost Liquor Sludge Ash 28
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
Thank you for your attention Christian Adam christian.adam@bam.de + 49 30 8104-5670 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: www.p-rex.eu 30