New Options for Coating Water and Wastewater

Treatment PlantsPresented by Presented by

Bruce SnyderBruce SnyderBusiness Development Manager Business Development Manager

Water and WastewaterWater and Wastewater

Protective Coatings Technologies

• Coatings technology for years remained the same.

• Raw material supplier began to seek a competitive advantage.

• Coatings manufacturers began to take advantage of new technologies.

• Today, coatings technologies are improving like electronics (very frequently).

Why?Prior to the Clean Water Act of 1972,

H2S concentrations were below 10 ppm

in most municipal systems. The result

was very gradual acid attack to concrete and

metals. As a result, thin film systems (<25m)

such as coal tar epoxy provided effective

protection for 10-15 years.

1980

Following the amendment of the Clean

Water Act of 1980, industrial pretreatment of

wastewater affluent to eliminate or reduce

the presence of heavy metals (lead,

mercury, cadmium) was mandated. Prior to

1980, these metals killed or retarded the

growth of bacteria.

Add Covers and Longer Detention Times

Consequently, H2S has risen to levels as

high as several hundred ppm, averaging

over 30 ppm in collection piping, manholes

and tanks. H2SO4 concentrations have risen

from solutions of 1.5% to as high as 7%,

resulting in pH ranges found to be as low as

1.5-2.5, and often less than 1.0 !

add decreased inflow/infiltration

The Result

Coating systems that served well prior to

1980, like coal tar epoxy, now often fail

in months, not years!

Microbial H2SO4 generation attacks steel,

concrete, and ductile iron.

Controlling Corrosion1. Change design parameters.

(Minimize slow flow or stagnant conditions in treatment stream)

2. Different materials of construction.(Use of vitrified clay, ductile iron, plastics, anti-microbial concrete)

3. Modification of sewage environment.(Raise pH above 9 temporarily to kill SRB; sulfate reducing bacteria)

4. Installation of barrier coatings!

Selection Criteria

• Remember! – ALL ORGANIC MATERIALS ARE PERMEABLE

• “Select materials or systems that provide optimum balance of performance, risk, and cost factors” (Quote – Concrete Repair Manual Vol. 1)

Why Flake Filled Topcoat?

• Flake Filled with inert material– MIO, Graphite, Glass, Mica

• Lower Co-Efficient of Expansion

• Reduce permeability (immersion service)• Increase abrasion resistance• Reinforces coating tensile & flexural

strength

Micaceous Iron Oxide Fe2O3

Crystals ofMIO arefracturedinto thinflakes.

Flakesthen

align inparallelfashion.

Types Of Flake ReinforcementTypes Of Flake Reinforcement

• Glass Glass

• Micaceous Iron Oxide (MIO)Micaceous Iron Oxide (MIO)

• GraphiteGraphite(resistance to halogenated acids)(resistance to halogenated acids)

Glass Flake Reinforced Amine Epoxy

• Upgrade to coal tar epoxy

• Lower permeability

• Corrosion, impact, and abrasion resistant

• Higher dry film thickness than unreinforced epoxies

Fast Cure Reinforced Immersion Grade Urethane

• Typically aromatic polyurethanes

• MIO reinforced

• Resistant to H2S and MIC corrosion

• Low temperature application

• Fast dry and cure times

• Monolithic application

100% Solids Epoxy Lining / Mortar/FRE

• Amine cured• Chemical Resistant• Resistant to hydrogen sulfide gas,

carbon dioxide gas, and microbiologically induced corrosion, and sulfuric acid attack.

• High build capabilities

100% Solids Epoxy Lining

100% Solids Epoxy Lining

100% Solids Polyurethane Elastomer

• Aromatic polyurethane • High film build capabilities• Flexibility• Quick setting – short downtime• Chemical resistance• Excellent abrasion and impact resistant• Vertical & overhead application• Monolithic application

Manhole Rehabilitation

100% Solids Polyurethane Elastomer

Fast Cure Polyurea

• Fast set and cure, short downtime

• Seamless, flexible and waterproof

• Chemical resistant

• Impact, tear, and abrasion resistant

• Bridges moving cracks to 1/8"

• Retains physical properties at -20°F to 250°F

Fast Cure Polyurea

AR425 Polyurea

Manhole Rehabilitation

Why?Stop I/I

(Infiltration

and Inflow)

and Rebuild

Chemical Grouts

• Chemical Grouts are broken down into 4 basic Categories.

1.Acrylamide

2.Acrylate

3.Acrylic

4.Polyurethane

Polyurethane’s

Polyurethane Chemical Grouts are broken in to three categories.

1.Hydrophobic

2.Hydrophilic

3.Multi Component

Hydrophilic & Hydrophobic

Hydrophilic• Flexible• Resin only• Great Bond• Absorbs Water• Medium to High

Shrinkage• Medium Expansion• Foam or Gel

Hydrophobic• Rigid and Flexible• Resin + Catalyst• Good Bond• Repeals Water• Low Shrinkage• High Expansion• Adjustable Set Times• Foam

Injection Procedures INJECTION STEPS

1. Determine the location of the leaks.

2. Slow Down Water Flow.

3. Drill Injection Port Holes

4. Insert injection Port or Wall Spear.

5. Mix Material

6. Inject Material

Insertion of Ports/Wall Spear

Injecting the back side

Complete encapsulation

Hydrophilic & HydrophobicPolyurethane Grouts

Here are four products designed to solve problems in Manholes:

Polyurethane foam A flexible Polyurethane for cracks and pipe penetration.Hydrophobic: A Polyurethane capable of shutting off gushing leaks and filling voids.Gel : A Polyurethane gel that will seal leaks and stop infiltration through the walls.OAKUM: A dry jute rope when soaked in Polyurethane is capable of filling large cracks.

Grouting Leaks in main line pipes can easily be accomplished using Acrylates or Acrylamide grouts.

Cementitious Repair Coatings• Portland cement by-products or calcium

aluminates

• Sprayed or trowel applied

• New product mixes allow radial spray with no entry into manhole

• Will degrade as the original surface did

Micro Silica/Fumed Silica Mortars

Advantages

1. Tighter matrix – lower permeability

2. Chemical resistant

3. Drive water off faster than pure portland

Disadvantages

1. Susceptible to MIC

2. Longer overcoat time than Calcium Aluminate Mortar

Microsilcate Application

Microsilcate Application

Microsilcate Application

Calcium Aluminate MortarAdvantages

1. With stands MIC longer than portland based materials

2. Faster set times (Typically 4-24 hours)

3. Can be used as a stand alone liner

Disadvantages

1. Susceptible to MIC, but at a reduced rate.

2. Cost

Two types available in the market.

Pure Calcium Aluminate MortarBinder or paste are calcium aluminate as well as the aggregate.

Calcium Aluminate MortarBinder or paste are calcium aluminate and the aggregate is typically silicon dioxide (Silica Sand)

Questions?