HELPING PHOSPHORUS RECOVERY BECOME MORE PROSPEROUS

Transcription

1 HELPING PHOSPHORUS RECOVERY BECOME MORE PROSPEROUS JIM FITZPATRICK SENIOR PROCESS ENGINEER

2 OVERVIEW Drivers and WWTP Sources EBPR and Struvite Recovery Recovery with Lower Effluent Limits 2

3 P-RECOVERY DRIVERS AND WWTP SOURCES 3

4 MORE MOUTHS TO FEED INCREASES THE NEED FOR PHOSPHORUS The phosphorus content of our land, following generations of cultivation, has greatly diminished. It needs replenishing. I cannot over-emphasize the importance of phosphorus not only to agriculture and soil conservation, but also the physical health and economic security of the people of the nation. Many of our soil deposits are deficient in phosphorus, thus causing low yield and poor quality of crops and pastures." -President Franklin D. Roosevelt,

5 HOW WILL WE MEET THE GROWING DEMAND? Recovery is part of long-term solution From S. Van Kauwenbergh. (2010), World Phosphate Rock Reserves and Resources. Presented at Center for Strategic and International Studies 5

6 PHOSPHORUS LINK TO HARMFUL ALGAL BLOOMS Lake Erie, 2011 Gulf of Mexico, 2007 (Courtesy of NASA) but much more complicated than just POTW effluent 6

7 P-RECOVERY IMPACTED BY P-REMOVAL AND BIOSOLIDS PROCESSING P-Removal Processes Chemical precipitation and hydroxide floc adsorption Enhanced biological phosphorus removal (EBPR) Media adsorption/ion exchange P-Recovery Alternatives Calcium phosphate precipitation Hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] and others Struvite precipitation MgNH 4 PO 4 6H 2 O Extraction from incinerator ash PhoStrip Struvite Precipitation Nutrient-Rich Digester Liquor Treated Digester Liquor 7

8 PHOSPHORUS WITH EBPR AND ANAEROBIC DIGESTION Primary Clarifiers Release from PAO Ohio WEA-AWWA 2014 Technical Conference & Expo Luxury Anaerobic Oxic Basins uptake EBPR Process by PAO Secondary Clarifiers Effluent P (0.5 1 mg/l) Particulate P Chemical Precipitation Anaerobic Digestion Thickening PAO in WAS (PO 4 ) 3-, Mg 2+, K + NH + 4 Soluble P Dewatering Particulate P Biosolids 8

9 EBPR AND STRUVITE RECOVERY 9

10 EBPR AND ANAEROBIC DIGESTION CAUSES (PO 4 ) 3-, Mg 2+ and K + quickly released by PAOs in WAS. NH 4 + released later during digestion. CONSEQUENCES Struvite formation Decreased biosolids dewaterability From Shimp, G.F.; Barnard, J.L.; Bott, C.B. It s always something. Water Environment & Technology, June 2014, 26(6), Alternatives to overcome unintended consequences 10

11 STRUVITE PRECIPITATION Mg 2+ + NH (PO 4 ) H 2 O MgNH 4 PO 4 6 H 2 O Mg usually limiting. MgCl 2 commonly added. High ph is favorable. NaOH commonly added. Nuisance Struvite Valuable Struvite The root cause of the problem is also part of the answer 11

12 DURHAM AWWTF ORIGINAL STRUVITE RECOVERY CONFIGURATION Primary Clarifiers Activated Sludge EBPR Process Gravity Thickener Thickening Centrifuge Tertiary Chemical Sludge Sludge Sludge Fermenter 90% Phosphate Removed Pearl Struvite Reactor Anaerobic Digestion 20% Ammonia Removed Crystal Green Slow Release Struvite Fertilizer Pellets %Mg Dewatering Centrifuge Biosolids to Land Application 12

13 DURHAM AWWTF STRUVITE RECOVERY FACILITIES Top of Reactors Screen Harvested Pellets Output Drier Sizing Screen Bottom of Reactors 13

14 Waste Activated Sludge Stripping to Remove Internal Phosphorus (WASSTRIP ) More protection from nuisance struvite deposits K + released with (PO 4 ) 3- and Mg 2+ shunted around digester NH 4 + released during digestion MgNH 4 PO 4 6 H 2 O precipitated Studies ongoing to quantify dewatering improvement from K + shunting K + (PO 4 ) 3- Mg 2+ K + (NH 4 ) + 14

15 5 YEARS OF STRUVITE RECOVERY BY CLEAN WATER SERVICES Durham AWWTF 25-mgd ADF, <0.1 mg TP/L May - Oct $2.5 million investment May Startup of 3 Pearl 500 struvite recovery units 2011 WASSTRIP increased P loading to units by ~80% May Upsized one Pearl 500 to Pearl 2000 Rock Creek AWWTF 35-mgd ADF, <0.1 mg TP/L May - Oct $4.5 million investment Fall Installed two Pearl 2000 units Future WASSTRIP planned after fermenters 5 to 7 year payback 40% less alum usage 20% less hauled biosolids 20% less NH 3 -N recycled 90% less P recycled Fertilizer revenue New generation of phosphorus recovery Rock Creek AWWTF Struvite Recovery Facility 15

16 GROWTH IN STRUVITE RECOVERY Minimize nuisance deposits Reduce P & N recycle loads Reduce P content of biosolids Improved biosolids dewaterability Beneficial recovery of nutrients 16

17 STRUVITE PRECIPITATION ALTERNATIVES Ostara Pearl MHI Multiform Kansas Environmental Management Associates (KEMA) Phred Aquatec Crystalactor CNP AirPrex 17

18 ALTERNATIVES FOR DIGESTER SLUDGE VS. CENTRATE/FILTRATE Biosolids dewatering costs drive recovery decision in many applications 18

19 PRE-DIGESTION PHOSPHORUS RELEASE ALTERNATIVES WASSTRIP P-stripping with acid/gas phased digestion From Barnard J. and Shimp G.; The Impacts of Biological Phosphorus Removal on Biosolids Dewatering; Proceedings of the Water Environment Federation, Nutrient Removal and Recovery MultiWAS Process Flow Diagram of Nine Springs WWTP (Madison Metropolitan Sewer District) 19

20 P-RECOVERY WITH LOWER PHOSPHORUS LIMITS 20

21 HOW LOW SHOULD WE GO? From Ohio EPA, Ohio Nutrient Reduction Strategy, June 28, Significant questions remain. Overall sustainability? Trading with nonpoint sources? Case-specific evaluations. 21

22 GENERAL RULES OF THUMB Effluent Concentration (mg-tp/l) 0.5 to to 0.3 Process Alternatives A. Chemical precipitation and floc adsorption B. EBPR with reliable VFA feed A and/or B with effluent filtration <0.05 Tertiary system Water Environment & Technology (Oct 2011) Some exceptions to the rules. Case-specific alternative evaluations recommended. 22

23 MOST ULTRALOW ALTERNATIVES RELY ON ALUM OR FERRIC CHEMISTRY Alternative Chemically enhanced clarification Two-stage granular media filtration Low-pressure membrane filtration Reverse osmosis Alum or Ferric Yes Yes Yes Yes Other Polishing filter generally required. Lamella settler, solids contact, ballasted flocculation options. Membrane bioreactor (MBR) or tertiary systems. Media adsorption / ion exchange No Filter pretreatment generally required Alum and ferric chemistry interfere with struvite recovery 23

24 NEW PHOSPHORUS ADSORPTION TECHNOLOGY Polymeric metal oxide media developed by Asahi Kasei Chemicals Long-term pilot studies completed in Japan and U.S. Exterior Surface Cross section Internal Structure Exterior Surface Cross Section Internal Structure 0.13-mgd demonstration at Kasumigaura Lake WWTP (near Tokyo) averaged TP < 0.03 mg/l during first year. Fibril Cavities 10-mgd facility on hold, pending need for ultralow limits 24

25 CONCEPT FOR MEDIA ADSORPTION / ION EXCHANGE WITH STRUVITE RECOVERY Primary Clarifiers Activated Sludge EBPR ASAHI Phosphorus Adsorption Media VFA Effluent Filter Sludge Fermenter & Thickener (PO 4 ) 3-, Mg 2+, K + Anaerobic Release Tank Thickening Centrifuge WASSTRIP OH- H+ K + Struvite Reactor Struvite Fertilizer Mg 2+ NH 4 + Anaerobic Digestion Dewatering Centrifuge Desorption Fluid (PO 4 ) 3-, OH- Biosolids MgNH 4 (PO 4 ) 6H 2 O 25

26 SUMMARY The need for phosphorus recovery is growing Viable recovery processes are commercially available 5 years of full-scale struvite recovery in U.S. If lower effluent TP required: Various alternatives available New adsorption/ion exchange media doesn t require metal salts Repeatable in-situ regeneration of media Potential integration with struvite recovery and EBPR 26

27 Jim Fitzpatrick Senior Process Engineer (913) Ting Lu Process Engineer (513) Andy Shaw Sustainability Practice Leader (913) Sid Sengupta Client Services Director (513) Dianne Sumego Client Services Director (913)

28 EXTRAS 28

29 RETURNING TO AGRICULTURAL ROOTS From K. Ashley et al. A brief history of phosphorus: From the philosopher s stone to nutrient recovery and reuse. Chemosphere (2011), doi: /j.chemosphere

30 STRUVITE PRODUCT ALTERNATIVES Ostara Crystal Green Multiform Harvest Fertilizer AirPrex MAP fertilizer KEMA TerraPhos 30

31 PEARL INSTALLATIONS Name Location WWTP Capacity Startup Date Gold Bar/Clover Bar (demonstration) Edmonton, AB 80 MGD May-07 Durham AWWTP Tigard, OR 20 MGD May-09 Nansemond WWTP Suffolk, VA 20 MGD May-10 York WWTP York, PA 20 MGD Jun-10 Rock Creek AWWTP Hillsboro, OR 30 MGD Mar-12 Slough STW United Kingdom 15 MGD Dec-12 H.M. Weir WWTP Saskatoon, SK 20 MGD Jan-13 Nine Springs WWTP Madison, WI 40 MGD Jan-14 Truckee Meadows WRF Reno, NV 40 MGD Dec-14 F. Wayne Hill WRC Gwinnett County, GA 50 MGD Jan-15 Gold Bar/Clover Bar Edmonton, AB 80 MGD Mar-15 Stickney WRP Stickney, IL 1,200 MGD Oct-15 Bonnybrook WWTP Calgary, AB 110 MGD Mar-16 Amersfoort Amersfoort, Netherlands 15 MGD Mar-16 31

32 AIRPREX INSTALLATIONS Name Location WWTP Capacity Startup Date Berlin WWTP Germany 125 mgd 2003 Moenchengladbach WWTP Germany 70 mgd 2007 Reest & Wieden WWTP Holland 31 mgd 2012 Amsterdam WWTP Holland 120 mgd

33 ASAHI ADSORPTION TECHNOLOGY Secondary Effluent Filter Treated Water Adsorption Towers A B C Acid Tank Adsorption Desorption Recovery Precipitation Reactor ph Control Tank Caustic Tank Neutralization Waste Carrousel Operation Solid/liquid separation Two columns in series Third column stand-by Phosphorus-Laden Solids Desorption Tank Lime Tank Offers in situ media regeneration and phosphorus recovery 33