CNP NUTRIENT RECOVERY TECHNOLOGIES MWEA Sustainability Seminar Josh Gable Regional Sales Manager
Discussion Outline AirPrex Deep Dive How it works Review of data Review of key benefits CNP CalPrex Basics History Brushite basics Summary
History of CNP and AirPrex
Where AirPrex Plugs In
So Why There?
So Why There? 1. Dewatering is always the problem area for nuisance struvite formation - Get it to form before dewatering and eliminate the issue 2. We want to mitigate sidestream phosphorus 3. Removing the soluble P upstream of dewatering improves the cake dryness and reduced the polymer requirement
So Why There? 9 8,5 MAP precipitation area ph 8 7,5 Mg 2+ in solution 7 10 20 30 40 50 60 70 80 90 100 110 120 130 140 PO 4 ortho-phosphat Concentration (mg/l) [mg/ l]
How it Works Raw Sludge (WAS & PS) Biogas Magnesium-Dosage Digester AirPrex Reactor Dewatering Air stripping Struvite output
How it Works MgCl 2 2 1 Aeration to strip out CO2+recirculate sludge 2 Addition of Magnesium Chloride (MgCl2) 3 MAP- Crystallisation and sedimentation 4 MAP- Separation and washing 1 Sequestration - OPTIONAL 3 4 Struvite
Notable Pilot Tests
Cake TS (%TS) What to Expect as a Result Improvement Cake Dryness 2 to 5 percentage points Reduction in Polymer 10 to 40 % reduction 29% 27% 15 gpm 90% Target Removal 25% 23% 21% 19% AirPrex Untreated Digestate Struvite sample collected during Airprex Pilot in Miami-Dade 17% 15% 25 35 45 55 65 Active Polymer Dose, lb/dt Data Collected during Denver Metro Pilot Test, Summer 2016
Concentriation PO4-P (mg/l) What to Expect as a Result 90% Reduction of Sidestream OP 600 500 Inflow Outflow AirPrex Cent Digested Cent 400 300 Struvite sample collected during Airprex Pilot in Miami-Dade 200 100 0 10/22 10/27 11/1 11/6 11/11 11/16 Date Data Collected during Sun Prairie, WI Pilot Test, Fall 2016
Concentriation PO4-P (mg/l) What to Expect as a Result 90% Reduction of Sidestream OP Subsequent Reduction in Digester TP 600 500 Inflow Outflow AirPrex Cent Digested Cent 400 300 Struvite sample collected during Airprex Pilot in Miami-Dade 200 100 0 10/22 10/27 11/1 11/6 11/11 11/16 Date Data Collected during Sun Prairie, WI Pilot Test, Fall 2016
mg P/L What to Expect as a Result Reduction in Digester influent Phosphorus as Observed at the SunPrairie, WI Pilot Test Modeling completed by MWH based on Denver Metro Pilot Pilot Test Suggests 30% Reduction in Digester TP Concentration when System Reaches Steady State. 550 Digestate P Conc n Pre Pilot Test Average 490 mgp/l At Conclusion of AirPrex Test 398 mgp/l 19% reduction in 16 days HRT of digester 25-50 days 500 450 400 350 300 250 200 10/22/2016 10/27/2016 11/1/2016 11/6/2016 11/11/2016 11/16/2016
Pilot Testing Summary
Example Installation Amsterdam, Netherlands Installed 2014
AirPrex - Amsterdam WWTP (Netherlands) Amsterdam-West WWTP (170 mgd) Struvite production: 2.5 t/d Start-up: 2014
AirPrex - Savings for Amsterdam Disposal: Polymer savings: Maintenance: $ 400,000/yr $ 350,000/yr $ 40,000/yr Revenue from Struvite pays for MgCl 2 ROI 7 Years
AirPrex Installations As of June 2017 Denver Metro Announced AirPrex Selected as Technology of Choice for their Nutrient Recovery Project
CNP CalPrex for Pre-Digestion Recovery
ppm Why Acid Phase Digestion Soluble Ions During Anaerobic Digestion 600 500 400 Phosphorus precipitated with calcium and magnesium Sample from 8 Aug 2007 300 200 100 0 Acid Thermo Meso GBT Filtrate Flow P Ca Mg
Recovery Potential (% Total P) Phosphorus Recovery Potential 70% 60% WAS Max Acid Digest Max 50% 40% 30% Post Digestion Filtrate Max 20% 10% 0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% % Total P solubilized Veolia Struvia CNP AirPrex Ostara Pearl CNP CalPrex
What is Brushite? Distinction of Phosphorus Minerals Brushite (dicalcium phosphate or dical) forms in slightly acidic conditions of ph 4.5 6.5 and is a good fertilizer. Ca 2+ + H 2 PO 4- + 2H 2 O CaHPO 4 2H 2 O + H + Struvite (magnesium ammonium phosphate) forms in slightly alkaline conditions of around ph 8 and is a good fertilizer. NH 4+ + Mg 2+ + HPO 4 2- + 6H 2 O NH 4 MgPO 4 6H 2 O + H + Hydroxylapatite forms under alkaline conditions of ph 9 and is NOT a good fertilizer. 3Ca 2+ +2HPO 4 2- + xh 2 O Ca3(PO 4 ) 2xH 2 O + 2H +
Concentration [mol/l] ph What is Brushite? Distinction of Phosphorus Minerals 0.040 P Precipitation from Acid Digest 14 0.035 0.030 12 10 0.025 0.020 0.015 0.010 0.005 8 6 4 2 0.000 0 0 0.01 0.02 0.03 0.04 0.05 Added calcium hydroxide [mol/l] Dissolved-P Brushite Struvite calcite ph
What is Brushite? Distinction of Phosphorus Minerals Brushite is a higher value product Commercial value = $250 - $300 / ton versus $100 / ton for Struvite
Fertilizer Comparison Statistical Analysis Brushite and struvite were compared to MAP, DAP, and TSP Various application rates to a P-deficient soil Corn yield and P in above ground dry matter were measured
CNP CalPrex Pilot
CNP CalPrex Pilot
CNP CalPrex Pilot
Key Benefits of CalPrex Lower chemical cost for Ca(OH) 2 versus MgCl 2 ~ $0.06 per lb Roughly 10-20% the cost of MgCl 2 on a per lb. of P-removed basis Where acid digester used Can remove highest amount of TP of currently available technologies Brushite has higher commercial value than Struvite
Summary Implementation of AirPrex Reduce sidestream OP by 90% Reduce digester influent TP by estimated 30% at steady state Improve Cake DS by 3 to 5 percentage point Reduce polymer requirement by 10 to 40% Implementation of CalPrex TP removal rates of over 50% possible as a separate stream Key to success is good P-release, best achieved via acid phase digester Produce higher value fertilizer Combined Solution Maximize TP diversion and fertilizer production while maximizing solids dewaterability
Questions?