Automated Odor Control Chemical Dosing Systems 1152 West 2400 South Suite C Salt Lake City, Utah 84119

OVERVIEW What Causes Odor and Corrosion in Wastewater Systems? What are the Consequences of Not Treating Hydrogen Sulfide? How and Why Do You Treat or Prevent Odors? What Makes AWS’ System Better? Actual Results in Clarksville, TN.

What Causes Odor and Corrosion in Wastewater Systems? Primary cause of odors in wastewater is hydrogen sulfide (H2S). H2S tends to form in wastewater anywhere sewage is allowed to go without oxygen for a significant amount of time. The usual suspects are long force mains from pumping stations. When sewage is discharged at the terminus of the force main the turbulence allows liquid sulfide to become airborne.

Pumping Station Discharge Manhole Force Main Wet Well with Sewage Pump Air relief valve Chemical Dosing System Diagrammatic View of a Pumping Station and Force Main Diagram not to scale

What are the Consequences of Not Treating Hydrogen Sulfide Worker Health and Safety Odor Corrosion and Destruction of Infrastructure

Worker Health and Safety Odor Threshold Offensive Odor Conjunctivitis/Respiratory Tract Irritation/Olfactory Paralysis Headaches/Nausea Throat and Eye Irritation Strong Nervous System Stimulation Apnea Death!!! “Rotten Egg” Odor Alarm OSHA/ACGIH TWA Exposure limit Threshold of Serious Injury Loss of Sense of Smell Imminent Life Threat Immediate Collapse With Respiratory Paralysis ppm H 2 S Toxicity Spectrum

Odor Rotten Eggs – H 2 S Properties Most noticeable of all odors Most noticeable of all odors Colorless toxic gas Colorless toxic gas Moderately soluble in water Moderately soluble in water pH, temperature, and turbulence driven pH, temperature, and turbulence driven

Diagram of Typical Cross Section of Force Main with no Odor Control Treatment. This could cause the following odors in local neighborhoods. Garlicky Garlicky Skunk Skunk Decayed cabbage Decayed cabbage Fishy Fishy Rancid Rancid

Corrosion and Destruction of Infrastructure Hydrogen Sulfide Corrosion Damage of Common Wastewater Infrastructures: Left Photo of Wet Well, Right Photo of Manhole

< 5 Years 5-10 Years Years Years > 50 Years Dissolved Sulfide (mg/L) Pipe Diameter (Feet) H 2 S Vs the Life Expectancy of Reinforced Concrete Pipes

Diagram of Typical Cross Section of Force Main with no Odor Control Treatment. As shown on the Graph, depending on the amount of Hydrogen Sulfide in your system, within 5 years can cause as much as $1 million in damage to infrastructure.

An Ounce of Prevention is Worth a Pound of Cure Cost of AWS System over 5 year period Installation and Service Charge$ Monthly Service Fee $ X 60 months = $24, Total$26, Estimated Cost of Infrastructure Damage$500k-$1 Mil

How and Why Do You Treat or Prevent Odors? How: Most cost effective method is usually chemical treatment at the wet well. Most common chemical used is calcium nitrate (Bioxide). Other effective chemicals are sodium nitrate, iron salts, hydrogen peroxide. Conventional method is to drip chemical into wet well at a constant rate.

How and Why Do You Treat or Prevent Odors? Why: Citizen Complaints Law suits Consent order Worker safety Sewer line and component failures Premature failure of system appurtances

How and Why Do You Treat or Prevent Odors? How: Most cost effective method is usually chemical treatment at the wet well. Most common chemical used is calcium nitrate (Bioxide). Other effective chemicals are sodium nitrate, iron salts, hydrogen peroxide. Conventional method is to drip chemical into wet well at a constant rate.

What makes the AWS system better? Utilizing proprietary software and a patent pending process, our system monitors the rate of change of the wet well level to apply a chemical dose rate to meet the system demand rather than a constant dose. The AWS system saves significant amounts of chemicals and therefore saves the customer significant amounts of money. The AWS system prevents harmful slug dosing of the wet well during low flow periods. This makes alternative chemicals to nitrate much more feasible to the customer.

Typical Odor Control Chemical Feed System

AWS Dosing System

Comparison CONVENTIONAL SYSTEMS AWS AUTOMATED SYSTEMS Constant set dose rate is applied throughout the day to meet the peak demand. Dose rate automatically adjusted throughout the day to meet the instantaneous demand. Over doses most of the day, yet often under doses during peak demand allowing odors. Achieves consistent and efficient odor control throughout day without over dosing. Creates high concentrations of chemicals in the wet well during low sewage flow periods. Maintains appropriate and safe chemical concentration in wet well. Cannot adjust for differences between weekdays, weekends, or holidays. Senses differences in daily flows and automatically adjusts dose rate. Continuous duty increases run times and reduces life of chemical metering pumps. Reduced heat, run times, and wear increase life of expensive chemical pumps.

Actual Results in Clarksville, TN The AWS system is currently installed in Clarksville, TN at the Sugar Tree pumping station and has lowered their chemical consumption by greater than 50 percent. The savings at this site equate to around $11,000 per year. Initial testing at additional sites in Clarksville are also showing 50 percent or greater reductions in chemical usage.