Phosphorus recovery at existing WWTP's - a step change from waste separation to fertilizer production

Transcription

1 Phosphorus recovery at existing WWTP's - a step change from waste separation to fertilizer production Peter Balslev, Suez Water (AS), Denmark Manchester July 4-5th

2 Agenda Phosphogreen Background for problems & solution Background of concept (partnership) Technology Concept & pictures Cases from Aarhus and Herning Circular economy

3 4 Problems Piping Digester wall 50 m 3 "sand" in digester

4 Problems (continued) Scaling in old pumps 5

5 And scaling in new pumps Problems (continued)

6 Mass balance, 0% recovery - before situation" Pct. of inlet total-p FeCl 3 inlet outlet WWTP 4 4% Pre-dewater Return sludge Digester 5 rejekt Final dewat. Sludge 96 96% 7

7 Concept background Partnership and development in Denmark Objective Providing a full value-chain for P recovery solution Challenge In 2010 Aarhus Water (Denmark) experienced problems with heavy struvite formations in digester, pipes etc. A partnership was formed to solve the problem and creat new values Process, design, technology Water utilities companies facing a challenge Agricultural Knowledge Centre approval of P product as fertilizer

8 Development Pilot testing Lab testing 3 steps up-scaling Full scale testing

9 Phosphogreen Functionality Process control Magnesium chloride is dosed flow proportional into the reactor inlet together with inlet reject water, dosing is regulated based on analysis of PO 4 weekly water outlet NaOH is dosed into the reactor controlled by ph measurement to keep ph value around 7.5, water recirculation Air lift pump secures internal recirculation as well as CO 2 stripping NaOH Internal recirculation pump secures up-flow velocity air inlet (centrates) MgCl 2 struvite extraction washing drying packaging

10 A stepwise change from removal to ressource recovery Chemical P-removal Primary precipitation Simultaneous P-removal Partly Bio-P process included in N-removal control Reduce return P-load from sludge dewatering Reduce precipitant Allow to strip P i digester More release of P from sludge dewatering More recovery Reduce more precipitant Better bio-p conditions Establish P-stripping before digester Reduce Struvite scaling issues

11 The chemical circle for P-removal No option for bio-p process High chemical bound P-content in sludge Chemical precipitation Me:P rel. >1 Low internal P-load Little P-release from digester sludge 95% of P in sludge

12 The bio-p circle for P-recovery Better conditions for bio-p process Lower chemical bound P-content in sludge Chemical precipitation Me:P <1 Include Bio-P Using process control 40% of P in fertilizer Higher internal P-load -> but recovered! More P-release from digester sludge 55% of P in sludge

13 Progression process towards P- recovery Chemical precipitation 0% rec. P-release from digester collected in recoveryprocess 20-35% rec. Prelease from biosludge and digester are collected in P-recovery process 40-50% rec.

14 15 Sludge analysis, Aaby WWTP 7.00% 6.00% 5.00% 4.00% 3.00% total-n Total-P 2.00% 1.00% Less P in sludge 0.00% sep-13 dec-13 jan

15 Results: Mass balance, 30% recovery - after situation, Aarhus case Pct. of inlet total-p FeCl 3 inlet outlet R/A 4 4% Pre-dewater Return sludge Digester Phosphogreen rejekt 36 Final dewater Sludge 66 66% 30% Struvite 16

16 Improved results: 45% recovery, Aarhus case - feasible Pct. of inlet total-p FeCl 3 inlet outlet WWTP 4 4% SSH Magnesium biosludge Digester P- recovery reject Decanter sludge % % 17

17 Quality of struvite and sludge, Aarhus plant Sludge Struvite 3 samples DM % 23,7 N % of DM 5,4 P % of DM 3,22 N % of sample 5,8 P % of sample 12,3 Mg % of sample 10,3 Land application in DK. Cd mg/kg 0,9 <0, Hg mg/kg 0,5 <0,1 0.8 Pb mg/kg 23 <0,2 120 Ni mg/kg 24,4 0,3 30 Cr mg/kg 17,1 <0,1 100 Zn mg/kg 580 2, Cu mg/kg 230 0, no heavy metals! Cd mg/kgp 28 <0, Hg mg/kgp 16 <0,8 200 Pb mg/kgp 714 <1, Ni mg/kgp 758 2,7 2500

18 Value making of PhosphorCare fertilizer PhosphoCare trademark in Denmark 2014 PhosphorCare Agricultural tests Corn and Rye growth tests Classification of PhosphorCare as fertilizer. Farm-tests for handling and use. Target: to form a consolidated method of how and where to use PhosphorCare Conklusion: PhosphorCare equals artificial fertilizer even though it is equally water soluble. PhosphorCare Approval 2014 Application for approval issued Q Approval from Danish national EPA and Ministry of agriculture and food obtained Q REACH registration Q Sales channel Kongerslev Kalk has signed a 2 year agreement with Aarhus Vand and Herning Vand for the distribution and sales of PhosphorCare Aarhus Vand and Herning Vand is open for new water companies to join their sales group Photo: Kongerslev Kalk s bag proposition

19 Application of Phosphogreen TM in the process line primary and/or secondary sludge anaerobic digestion dewatering sludge cake for disposal/ land application water back to the headworks application field: WWTP capacity > 40,000 PE biological phosphorus removal anaerobic digestion phosphorus conc. in digested sludge centrates 70 mg/l THP-processes - Cambi Phosphogreen TM struvite

20 Combined pre-dewatering and final dewatering reject primary sludge sludge cake for disposal anaerobic digestion dewatering secondary sludge from P-stripping tank dewatering water back to the headworks struvite Phosphogreen TM

21 Front view of reactors and plant

22 Bottom part of the reactor and recycle pump Recycle pump

23 Screening of struvite product Drying of struvite product

24 Drying of struvite product, test plant Åby

25 Silo and bagging of final product

26 Phosphogreen Summary Advantages of investment Innovative & effective reject water treatment solution Combines well with Anammox treatment Overall OPEX Cost advantage Green Image phosphorus recovery and reuse ROI ~7 years depending on plant The product is approx. 2 mm pellets ready for use as fertilizer P=12,5% N=5,5% Mg= 10% Value creation No or very reduced scaling problems Reduced chemical use for chemical P removal Reduced costs for sludge dewatering(polymer) Reduced energy uptake for nitrification Less sludge produced A fertilizer with high value: Struvite Residual sludge with better N:P balance

27 Our references: Aarhus, Denmark, ,000 PE Herning, Denmark, ,000 PE

28 Case for Phosphogreen Marselisborg WWTP Reject water treatment project ( PE)

29 Marselisborg WWTP Main Flow Diagram Primary sludge Aarhus bay Return sludge B SF Aarhus bay Aarhus bay Screenings Secondary sludge 23 Power and heat 28 RT Reject water 9 RB Sludge Sand Primary water flow Secondary water flow Sludge Biogas Sand and grease Screenings Chemicals New parts/flows 1: Catchment area pumps 2: Coarse screen 3: Overflow basin 4: Inlet pumping station 5: Inlet screen 6: Screening press 7: Grit chamber & grease trap 8: Grease tank 9: Sand washer plant 10: Chemical tank (PIX dosing) 11: Overflow tank 12: Primary clarifiers 13: Biological tanks (Nitrification/denitrification) 14: Secondary clarifiers 15: Intermediate pumping station 16: Sand filters 17: Outlet pumping station 18: Sludge thickeners 19: Sludge pre-dewatering 20: Sludge buffer/thickeners tanks 21: Anaerobic digesters 22: Gas storage tank 23: Gas treatment (activated carbon) 24: Gas boiler (standby) 25: Gas motors 26: Homogenizing/storage tanks 27: Final sludge dewatering 28: DEMON Anammox side-stream

30 Marselisborg WWTP Main Flow Diagram Primary sludge Aarhus bay Return sludge B SF Aarhus bay Hydrolysis P-rec. 1 Aarhus bay Screenings Secondary sludge 23 Power and heat 28 RT Reject water 9 RB P-rec.. 2 Sludge Sand Primary water flow Secondary water flow Sludge Biogas Sand and grease Screenings Chemicals New parts/flows 1: Catchment area pumps 2: Coarse screen 3: Overflow basin 4: Inlet pumping station 5: Inlet screen 6: Screening press 7: Grit chamber & grease trap 8: Grease tank 9: Sand washer plant 10: Chemical tank (PIX dosing) 11: Overflow tank 12: Primary clarifiers 13: Biological tanks (Nitrification/denitrification) 14: Secondary clarifiers 15: Intermediate pumping station 16: Sand filters 17: Outlet pumping station 18: Sludge thickeners 19: Sludge pre-dewatering 20: Sludge buffer/thickeners tanks 21: Anaerobic digesters 22: Gas storage tank 23: Gas treatment (activated carbon) 24: Gas boiler (standby) 25: Gas motors 26: Homogenizing/storage tanks 27: Final sludge dewatering 28: DEMON Anammox side-stream

31 32 Marselisborg WWTP New building

32 50% recovery - planned Pct. of inlet total-p FeCl 3 (Reduced) inlet 100 Primary sed outlet Stripping PO 4 WWTP % Magnesium Decanter Digester P-recovery reject Decanter sludge ~46% ~50% 33

33 Questions? Suez Water A/S Rugaardsvej 5, 8680 Ry, Denmark Phosphorgreen Tel: Mobile/Direct: mail; 34