Overview
Overview
Aulick recently partnered with a private company who was managing a wastewater collection system in Indiana. Our objective on the project was the treatment and removal of current hydrogen sulfide issues in the collection system, as well as the prevention of any future hydrogen sulfide.
Location
Indiana
Market
-
Odor Control
Introduction
Introduction
Hydrogen Sulfide is a colorless, toxic, highly flammable gas with a foul, pungent odor similar to that of rotten eggs. Often referred to as “sewer gas”, hydrogen sulfide is a result of the breakdown of organic matter by bacteria, typically in an oxygen deprived environment such as a collection system or wastewater treatment plant.
Controlling this hazardous gas is one of the most challenging problems facing collection system personnel today. Not only is it a nuisance, hydrogen sulfide has the potential, even at low concentration levels, to pose extreme safety hazards for plant personnel, while its corrosive nature is detrimental to plant and collection system equipment.
Challenge
Challenge
In the case of this project in Indiana, sulfur compounds were the predominant odor constituent and are characterized by a strong, pungent odor that can be identified from great distances. The concentration of sulfur compounds are dependent upon several factors such as temperature, weather, wind flow, microorganism count and residence time in treatment process. Some odorous compounds are considered offensive even at low concentrations. For example, ammonia at 2-5 ppm and mercaptans as low as 1 ppm.
Aulick looked at the following lift station data points to determine Nitra-Nox feed rate:
- Lift Station A: Average daily flow = 145,920 GPD. Lift Station A pumps 7,284’ through an 8” force main and 5,263’ through a 16” force main. Based on the average daily flow and size/length of the force main, the average retention time for Lift Station A force main is 3 hours in the 8” line and 9 hours in the 16” line. The total average retention time before discharging is 12 hours. Based on these insights, the estimated Nitra-Nox feed rate at Lift Station A was 34 gallons per day.
- Lift Station B: average daily flow = 300,000 GPD. Lift Station B pumps 0.25 miles through a 12” force main and 5 miles through an 18” force main. Based on the average daily flow and size/length of the force main, the average retention time for Lift Station B force main is 0.62 hours in the 12” line and 28 hours in the 18” line. The total average retention time before discharging to the wastewater treatment plant is 28.6 hours. Based on this data, the estimated Nitra-Nox feed rate at Lift Station B was 112 gallons per day.
Our Solution
Our Solution
The chemistry suggested in this application was Nitra-Nox. Nitra-Nox utilizes two types of chemistry to first remove any existing hydrogen sulfide and then offers alternative chemistry that has a weaker oxygen bond than the sulfur-oxygen bond in sulfates. In the end, Nitra-Nox will prevent hydrogen sulfide from being produced.
Based on the feed rates presented above, Aulick installed a 1500 Gallon Tank Mount Chemical Feed System at Lift Station A and a 2100 Gallon Tank Mount Chemical Feed System at Lift Station B to feed Nitra-Nox.
Learn more: Nitra-Nox
Our Results
Our Results
After system installation and trial, our partner in Indiana was able to successfully reduce hydrogen sulfide levels at both Lift Stations to an acceptable level. Aulick personnel continue to monitor feed sites and conduct regular hydrogen sulfide gas and liquid testing to ensure optimal Nitra-Nox feed rates and absence of corrosion-causing hydrogen sulfide.