NUTRIENT RECOVERY PROCESS Dr. Rakesh Govind PRD Tech, Inc Mentor Avenue; STE 400A Cincinnati, OH Presentation at Florida Water Resource Conference, April 2016 April 26, 2016

NUTRIENT CHALLENGE One of the major concerns regarding municipal wastewater treatment plant discharge is the rising concentration of nutrient compounds, specifically nitrogen and phosphorus; Wastewater treatment plants that employ conventional biological treatment processes, designed to meet secondary treatment effluent standards, typically do not remove total nitrogen (TN) or total phosphorus (TP) to the extent needed to protect receiving waters; Investment cost of a biological nitrification/denitrification process is substantial; and Ammonia production is an energy-intensive process and the world is running out of phosphorus; Recovery of both N and P are essential, technically feasible and economically viable.

What is Nutrient Recovery? Effluent Water (N, P) Calcium Hydroxide Calcium Phosphate Precipitation Fertilizer Product Ammonia Gas Recovery Ammonia-Water, Ammonium Salt Solution Treated Effluent Pilot-Scale unit sold to Johnson Matthey for Ammonia Recovery only; Pilot plant for N and P recovery will be tested at the Ventura, CA municipal plant, starting May 2016

COMPETING TECHNOLOGIES Recovery of struvite (magnesium ammonium phosphate) from digester supernatant; Only 5-15% of nitrogen is recovered through phosphate-based precipitation processes; Production of biosolids-enhanced granular inorganic fertilizers (e.g., Unity Envirotech’s fertilizer granulation process and VitAG’s ammonium mix process); Air stripping of ammonia followed by gas absorption to produce ammonium sulfate; Full-scale ammonia-stripping towers have been decommissioned because of operational problems and cost; and Liqui-Cell’s Membrane process for directly converting ammonia in water to ammonium sulfate using a membrane; However, the presence of surfactants results in process failure.

PRECIPITATION OF CALCIUM PHOSPHATE ChemicalCompositionCa/P Ratio Dicalcium Phosphate DihydrateCaHPO 4.2H 2 O1.00 Octacalcium PhosphateCa 4 (HPO 4 ) 3.3H 2 O1.33 Tricalcium PhosphateCa 3 (PO 4 ) HydroxyapatiteCa 5 (PO 4 ) 3 OH1.67 Calcium Phosphate precipitation was experimentally studied by mixing Calcium Chloride and Potassium Phosphate in a 500 mL beaker using various Ca/P ratios. Prior to mixing, pH was adjusted initially and then maintained automatically by adding NaOH or HCl. All experiments were performed at 21.5 deg C. Chemical Equilibrium Constant Dicalcium Phosphate Dihydrate CaHPO 4.2H 2 O (s)  Ca 2+ + HPO H 2 O pK = /T – T [1] Octacalcium Phosphate Ca 4 (HPO 4 ) 3.3H 2 O  4Ca PO H + + 3H 2 O pK = at 20 deg C [2] Tricalcium Phosphate Ca 3 (PO 4 ) 2  3Ca PO 4 3- pK = /T – T [3] Hydroxyapatite Ca 5 (PO 4 ) 3 OH  5Ca PO OH - pK = /T T [4]

PRECIPITATION OF CALCIUM PHOSPHATE pH = Precipitation Efficiency (%) Ca/P = 1.67

AMMONIA-AMMONIUM EQUILIBRIUM

MEMBRANE DEGASSING

COST ANALYSIS Typical sludge filtrate from a municipal plant: mg/L ortho-P; mg/L of ammonium N $ $1.34/lb N removed by Nitrification $0.50/lb Nitrate-N removed using methanol $ $0.59/lb P removed – only a fraction is removed $ $2.43/lb N and lb P removed – Total cost Nutrient Recovery Process Calcium Hydroxide $300/dry ton Lime consumption is 1.5 x total alkalinity If total alkalinity is 1,000, lime cost will be $0.75/lb P removed Recovers >95% of P and > 98% of N

DETAILED COST ANALYSIS

SUMMARY Nutrient Recovery is a novel, energy-efficient, membrane-based Process that simultaneously recovers N and P from a wastewater stream; Process produces useable products: P fertilizer and Ammonium Solution – fertilizer, wastewater disinfection, NOx controls, etc.; Pilot-Scale units have been built and supplied; Recovers > 95% P and >98% N from a wastewater stream; Physical-Chemical process with favorable economics compared to biological treatment systems; Produces saleable products – potential income generators; and Can be applied to municipal plant effluents, anaerobic digester effluents, Sludge treatment facilities, HCTP effluent.