Presentation on theme: "Challenges in U.S. Wastewater Infrastructure. Thioguard ® TST A common sense solution to a billion dollar problem."— Presentation transcript:
Challenges in U.S. Wastewater Infrastructure
Thioguard ® TST A common sense solution to a billion dollar problem.
*American Society Of Civil Engineers “U.S. Water Infrastructure Needs” 3/28/01 American wastewater systems currently require $12 billion* a year more than available funds to replace and failing infrastructure. And the shortfall is increasing every year… aging The American Society of Civil Engineers (ASCE) has reported to Congress and the Senate…
Compared with roads and bridges, aging is not the underlying problem in this case. However…
In 1977 the clean water act* increased treatment requirements for municipal wastewater. *Recommended by ASCE
This legislation has contributed to subtle changes in wastewater chemistry which increased sulfide production across the country. The result has quietly cost U.S. taxpayers billions of dollars. This legislation has contributed to subtle changes in wastewater chemistry which increased sulfide production across the country. The result has quietly cost U.S. taxpayers billions of dollars.
Wastewater has changed. It’s become more corrosive. Data provided by the City of Los Angeles Data courtesy of the City of L.A., CA More Corrosion Today, wastewater infrastructure is subject to much more corrosion than before 1980.
Sulfide gas is converted to corrosive sulfuric acid on surfaces inside sewers. This acid dissolves concrete and metal.
That’s why, in 2000 the EPA estimated municipal sewers subject to corrosion were failing six times faster than the rate they’re being repaired.
By 2016 the EPA now expects more than 50% of the country’s 600,000 miles of major sewer lines will be in poor, very poor or inoperable condition. Tucson, Arizona
Here’s how it happens… Acid corrosion is the problem.
Other bacteria present in the water convert sulfates to sulfides. This causes the rotten egg smell, hydrogen sulfide gas (H 2 S). When the dissolved oxygen concentration falls below 0.1 mg/l, the water becomes septic. H 2 S Gas pH ~ 7 D.O.<0.1 mg/l Bacteria in the wastewater consume oxygen. O2O2 O2O2 O2O2 Sewer Wastewater Bacteria
SO HS - H2SH2S H2SH2S H 2 S Gas H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S In water at pH 7, about 50% of the dissolved sulfide converts to H 2 S gas.
On the surfaces above the water, H 2 S gas is converted to strong sulfuric acid by Thiobacillus bacteria. This acid corrosion, not “aging”, then dissolves the infrastructure. SO HS - H2SH2S H2SH2S H2SH2S Thiobacillus + O 2 = H 2 SO 4 Acid Attacks Concrete And virtually nothing is being done to stop it from happening.
Collapses routinely occur when preventable corrosion is allowed to continue unchecked. SO HS - H2SH2S H2SH2S H2SH2S + O 2 = H 2 SO 4 Acid Attacks Concrete Once rebar is exposed, the sewer is structurally compromised.
Hydrogen sulfide corrodes cast iron pipe, valves and fittings:
Hydrogen sulfide corrodes manhole and wet well structures:
Resulting in SSO’s, disruptive flows and expensive emergency repairs:
Widespread corrosion is “relatively” new and although much faster today, it still happens gradually. Structural problems and collapses take years to develop. (But they are happening regularly now.) Few wastewater professionals really recognize and understand the extent of the problem. How could this happen?
When odors or sewer collapses draw public attention, engineering consulting firms tend to recommend capital intensive solutions. (See the ASCE reports to congress where, for example, the problem is incorrectly presented as aging infrastructure instead of corrosion.) How could this happen?
The rate of corrosion can be assessed with a simple surface pH test.
Corrosive conditions are the problem and that can easily be detected using a simple, inexpensive surface pH test.
Surface pH tells the whole story…
Red is bad, green is good. 7= Neutral Above 7 = Basic Below 7 = Acidic
Red is bad, green is good.
Source L.A.County San District Corrosion Rate (in./year) pH Corrosion Range years Years of Life (2” of sacrificial concrete) 100 Surface
Surface pH ≥ 4; Life Cycle = 100 yrs Sewer design life is generally based on 100 years of useful service.
Source L.A.County San District Corrosion Rate (in./year) pH Corrosion Range years of useful life Years of useful life 4 Surface pH ≥ 4; Life Cycle = 100 yrs
When the surface pH falls below four, sewer life cycle costs increase exponentially… 1250% For example, the difference in annual cost between surface pH 4 and 2 is…
Source L.A.County San District Corrosion Rate (in./year) pH Corrosion Range years of useful life 8 years Years of useful life >200 years of corrosion life Source L.A.County San District
Surface pH of two or lower is now common. But most cities (or consulting firms) don’t measure for it.
The value of U.S. sewers is estimated to be over $1 Trillion*. *Wade, Mark, “ Controlling Inflow and Infiltration In Wastewater Collection Systems”, Why is this important?
About 10% are large diameter (>18”) which are subject to corrosion. These sewers alone are worth more than $100 billion.
Simple Life Cycle Cost; $100 Billion/100yrs = $ 1 Billion/yr Surface pH ≥ 4; Life Cycle = 100 yrs
Surface pH 2.0; Life Cycle = 8 yrs Simple Life Cycle Cost; $100 Billion/8yrs = $12.5 billion/yr But if the pH is allowed to fall…
According to the American Society of Civil Engineers – “Standard operating practices must change.” “New solutions are needed.”
Thioguard is a simple new solution to this billion dollar problem.
Thioguard ® TST Total System Treatment A practical, non-hazardous, system-wide strategy for cost effective management of odor and corrosion in wastewater collection and treatment networks.
Thioguard is industrial strength milk of magnesia. Thioguard neutralizes the acid processes that cause sewer corrosion. Thioguard is a registered trademark of Premier Chemicals and is patented for use in municipal collection systems under U.S. patent numbers 5,718, ,833, ,554, ,834,075, 6,056,997
Corrosion which limits system life expectancy X X Thioguard X
Biological Treatment Secondary Clarifier Digestion Effluent Conditioning Dewatering Primary Treatment Collection System Disinfection Biological Treatment Primary Treatment Conditioning Dewatering Biosolids Digestion Secondary Clarifier Collection System Effluent Disinfection Thioguard ® TST And it improves wastewater treatment at the plant.
SO HS - H2SH2S H2SH2S H 2 S Gas H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S H2SH2S Recall this slide showing the relationship between wastewater pH and hydrogen sulfide gas?
The red area represents how much gas is produced in this example. The amount of gas produced is affected by the wastewater pH. Higher pH = less gas. Here’s what Thioguard does. > 80% Reduction H 2 S Gas Wastewater
Twenty gallons of Thioguard added to one million gallons of wastewater reduces corrosion by over 80%. The cost to treat 10% of the entire U.S. wastewater flow is less than $50 million/year.
Corrosion Rate Vs. Wastewater pH Without Thioguard With Thioguard > 80% Less Corrosion Corrosion
Added directly to wastewater Thioguard stops odors, corrosion and grease buildup that cause blockages and sewer failures. Thioguard ® TST Total System Treatment And Thioguard is environmentally safe and improves wastewater treatment and discharge water quality.
Red is bad, green is good. What color is your system?
Thioguard ® TST A common sense solution to a billion dollar problem.