WEAO2012 Technical Conference USING ONLINE ANALYZER FOR OPTIMIZING CHEMICAL PHOSPHORUS REMOVAL PROCESS IN MUNICIPAL WASTEWATER TREATMENT Ottawa, Ontario, Canada April 24, 2012 Wei Zhang, David Roskowic ASA Analytics, Inc. (262)

Overview Phosphorus is the target nutrient in Great Lake region 1976 Ontario MOE a six-year study called for installation of phosphorus removal facilities 1978 The Great Lake Water Quality Agreement (US and Canada) put phosphorus removal as primary concern of nutrient removal Lake Simcoe phosphorus removal review report (XCG Consultant), evaluated 14 WWTPs discharge to the watershed Current discharge permit 0.1 – 0.5 mg/l as TP, some are even lower

Presentation Focus Overview of chemical phosphorus removal fundamentals from operational cost perspective With primary focus on the rule of online analyzer nutrient analyzer plays in chemical phosphorus removal Case histories

Statement of the Problem TP > 1.0 mg/L biological phosphorus removal TP < 1.0 mg/L chemical precipitation, or combination of chemical & biological Existing Treatment might not designed for phosphorus removal Flow pacing or set at a constant flow rate to meet the worst-case scenario

Chemical P Removal Basics Aluminum or iron salts are used for phosphorus chemical precipitation Al 2 (SO 4 ) 3. (14H 2 O) + 2H 2 PO HCO3 - –» 2AlPO 4 + 4CO 2 +3SO H 2 O FeCl3. (6H 2 O) + 2H 2 PO HCO3 - –» FePO 4 + 3Cl - + 2CO 2 + 8H 2 O

Right Amount Chemicals? US EPA Nutrient Control Design Manual (2009) Alum to P molar ratio 1.38 : 1 for 75% removal 1.72 : 1 for 85% removal 2.3 : 1 for 95% removal Iron to P molar ratio 1 : 1 is required with a supplemental amount of 10 mg/l iron added to satisfy the formation of hydroxide.

“Common Practices” The following methods are often used for determination of “right amount” chemicals Jar Testing or Bench Testing Historical Trending Third Party Laboratory Analysis Plant’s Lab Analysis These methods are often labor and time consuming.

A Proposed Solution Online Phosphorus Analyzer Real time Continuous monitoring SCADA-linked for automatic dosing control Flexible for “feed forward” or “feed back” control Key – Chemical Saving

Ortho-P vs. Total-P Total Phosphorus Organic portion inorganic portion Why measure ortho-P in process control Ortho-P is dissolved portion Biological process converting P from un-dissolved form to dissolved form Chemical precipitation removes Ortho-P Relationship between ortho-P and Total-P Clarifier or filtration performance is important

Online Phosphorus Analyzer Total Phosphorus Analyzer Ortho-Phosphate Analyzer Chemical dosing control – Ortho-phosphate analyzer Spectrometry with wet chemistry Ortho-P reacts with ammonium molybdate to form vanadomolybdophposphoric acid (yellow color) Blue Method

AppliedSpectrometry Associates, Inc.

Installations & Case Histories Kiel, Wisconsin 0.9 mgd Activated sludge process Phosphorus permit limit 1.0 mg/l A cheese factory is the major contribution source Online analyzer data “feed back” to SCADA for ferrous sulfate dosing 20% chemical expense saving

Installations & Case Histories New London, Wisconsin 2 mgd Activated sludge process plant Phosphorus permit limit 1.0 mg/l Online analyzer data “feed back” to SCADA for ferric chloride dosing control $900 per month chemical expense saving

Installations & Case Histories Sheboygan, Wisconsin WWTP servicing population of 50,000 Current phosphorus limit is 1.0 mg/l Future phosphorus limit will be 0.05 mg/l Ferric chloride spending $160,000 annual with current limits First online phosphate analyzer installed in 2010 Second online phosphate analyzer just installed data “feed back” to SCADA for ferric chloride dosing control

AppliedSpectrometry Associates, Inc.

Installations & Case Histories Hite Creek, Kentucky Unpredicted phosphorus load from nearby industrial source Using Alum solution for phosphorus precipitation Plant is able to set up improved alum feed rate for different days of the week to match the expected P load based, using 4 months’ data collected from online analyzer Daily alum dosage reduced from 200 gallon/day to 100 gallon/day

Installations & Case Histories Waupun, Wisconsin Case study by Steven Arant of Donohue Associates (now AECOM) Study conclusion Comparing single point chemical dosing to multiple points chemical dosing, the later save chemicals and produces less sludge.

Installations & Case Histories Hagerstown, Maryland A demo project funded by the State of Maryland Discharge limit TN = 3.0 mg/l, TP = 0.3 mg/l To demonstrate the conventional technologies can achieve the goal Tertiary biological denitrification filter for N and chemical P removal Full scale installation in 2010 based on the result of the successful demo

Phosphorus Analyzer Selection Check References Interference compensation Self-cleaning and self-zeroing Sample handling Maintenance requirement Overall cost of ownership

Conclusion Meeting tightening discharge limitation Quick response to concentration changes Chemical cost savings Reduce of maintenance burden