chlorine contact chamber to uv channel project

Chlorine Contact Chamber to

UV Channel Project

Brian Hannon P.E, Moore & Bruggink

Outline

• Disinfection Basics

▫ Why

▫ Types

• Ultraviolet Disinfection Technologies

• Case History – Charlotte, MI

▫ Existing Cl2 Chambers

▫ Hydraulic Issues

▫ Selected Technology

▫ Project Design

▫ Construction Progress

Wastewater Disinfection

• Critical component of wastewater treatment

• Wastewater contains dozens of potential pathogenic viruses, bacteria, and protozoa.

▫ Crypto, E-coli, Giardia

Images: CDC.gov

Wastewater Disinfection – Why?

• Stops spread of some dangerous bacterial and viral diseases

Diseases that can be passed through

non-disinfected wastewater

• Dysentery

• Typhoid Fever

• Cholera

• Gastroenteritis

• Giardiasis

• Hepatitis A

• Cryptosporidiosis

• Salmonellosis

• Etc…….

Types of Disinfection

• Chlorination

• Ultraviolet

• Ozone

• Chlorine Dioxide

• Chloramination

• Peracetic acid

• Pasteurization

Chlorination


▫ Direct oxidation/destruction of the cell wall

(lysis)

• Types:

▫ Chlorine Gas

▫ Sodium Hypochlorite

Liquid

Tabular System

On-site Generation

Chlorination

• Advantages:

▫ Reliable, easy to operate, familiar, and cost effective

• Disadvantages:

▫ Chlorine gas is toxic, safety risk

▫ Corrosive

▫ Residual can be harmful to aquatic systems

▫ Toxic Disinfection Byproducts (trihalomethanes)

(ex; chloroform)

Chlorination

• Removing Residual

▫ Sulfur dioxide

▫ Sulfite Salts

Sodium sulfite

Sodium bisulfite

Sodium metabisulfite

▫ Polishing Pond

Ozone


▫ Cell lysis through oxidation

▫ Produces powerful oxidant hydroxyl radicals

• Application:

▫ Via Contact Chamber

▫ On-site generation

Ozone

• Advantages

▫ No toxic disinfection byproducts

▫ No residual removal

▫ Also reduces odor

▫ Short contact time

• Disadvantages

▫ Ozone in high levels is toxic to humans

▫ Off gas from contactors must be destroyed

Chlorine Dioxide


▫ Direct Oxidation/Cell Lysis

• Advantages

▫ Highly effective

▫ Minimized disinfection byproducts

• Disadvantages

▫ More expensive than chlorine

Chloramination

• Formed from reaction of ammonia and chlorine.

• Disinfection Basics:


• Advantages:

▫ Ammonia ties up chlorine preventing organochloramines (non-germicidal)

▫ Minimize THM and other disinfection byproducts

• Disadvantages:

▫ Difficult to control due to potential for variable ammonia in wastewater

Peracetic Acid

• Mixture of acetic acid and hydrogen peroxide

• Colorless with Strong Odor

• Newer technology – first in US was 2005



Peracetic Acid

• Advantages:

▫ no toxic byproducts

▫ short contact time

▫ ease of implementation

▫ low capital

▫ no subsequent process (dechlorination)

• Disadvantages:

▫ increased organic content in effluent

▫ high operational cost due to availability

Pasteurization • Disinfection Basics:

▫ Thermal inactivation

▫ Rapidly heat wastewater effluent to min 180 degF for minimum time 10 mins

Pasteurization

• Disinfection Basics: ▫ Thermal inactivation ▫ Rapidly heat wastewater effluent to min 180

degF for minimum time 10 mins

• Advantages: ▫ no toxic byproducts ▫ short contact time ▫ no subsequent process (dechlorination)

• Disadvantages: ▫ Need heat! ▫ Also need to cool to prevent damage to discharge

Ultraviolet Disinfection

• Disinfection Basics:

▫ Induces photo-biochemical change in microorganisms (renders sterile)

▫ Dimerization of nucleic acids (DNA and RNA) and proteins

▫ Most effective at 254 nM wavelength

Ultraviolet Disinfection

• Advantages:

▫ Safer than using chemicals

▫ No residuals to remove

▫ Short Contact time

▫ Cost Effective

• Disadvantages:

▫ Need relatively “clear” water

▫ Bulb life is ~1.5-2 years

Types of UV Disinfection Lamps

• Low Pressure, High Intensity

• Medium Pressure, High Intensity

• Low Pressure, Low Intensity

Types of UV Disinfection Equipment

• Horizontal in Channel


• Vertical In-Channel


• In-Pipe Units


• Lamps on Outside Units

Case History – Charlotte, MI

• Project: Conversion of Existing Cl2 Tank to Ultraviolet Disinfection


• Plant = .9 MGD Average Flow

• Screening and Grit Removal, Primary Clarifiers, Trickling Filters, Final Clarifiers, Tertiary Filtration, then Cl2 and Bisulfite

• Outfall to Battle Creek

Design Challenges

• Average Flow = .9 MGD, but Design UV system for plant Peak flow = 4.86 MGD

• Low amount of head to work with between inlet to chamber and outlet

• Parshall Flume to measure effluent flow

• Tertiary filters require backwash reservoir

• Limited Space within existing tank

Design Elements

• Magnetic Flow Meter

▫ Gooseneck outlet piping

• Parallel UV Channels

▫ Limited space for series

▫ S-pattern wouldn’t allow for hydraulics

• Inlet gates for flow control and energy savings

▫ Each channel rated for 2.4 MGD

▫ Turn off when flows are low

• Fixed Finger Weirs

Existing Chlorine Contact Tanks

Hydraulic Challenges

Hydraulic Challenges

dv(GPM) Cycle time (min) v(gal)

dvin(0-19) = 347.22 19.00 6597.22

dvout(0-4) = 1500.00 4.00 6000.00 ***1400 GMP + 100 GPM Surface Wash

dvout(5-9) = 1800.00 5.00 9000.00

dvout(10-19)

= 1500.00 10.00 15000.00 ***1400 GMP + 100 GPM Surface Wash

Total Volume In Total Volume Out Volume Needed

6598 30000 23402

Volume Needed Excess Volume Construction Excess Volume Post Construction

23402 2628.47 10173.30

• Tertiary Filter Backwash Volume

O&M Costs– Charlotte, MI

• Chlorine Costs/Year = $3,000

• Bisulfite Costs/Year = $3,500

• System Maintenance Costs/Year $3,000

• Safety Equipment Costs/Year $1,000

TOTAL EXISTING O&M/yr $10,500

• Energy and Maintenance on UV/Yr = $5,000


• FRP Shelter over the new UV System

Questions?

Brian Hannon, P.E. Moore & Bruggink, Inc. [email protected] (616)363-9801

mailto:[email protected]

chlorine contact chamber to uv channel project

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