Inspection of Disinfection Components

NC Certified Subsurface Systems Inspector Training School

CIDWT DisclaimerThese materials are the collective effort of individuals from

academic, regulatory, and private sectors of the onsite/decentralized wastewater industry. These materials have

been peer-reviewed and represent the current state of knowledge/science in this field. They were developed through a

series of writing and review meetings with the goal of formulating a consensus on the materials presented. These materials do not necessarily reflect the views and policies of the Consortium of

Institutes for Decentralized Wastewater Treatment (CIDWT). The mention of trade names or commercial products does not

constitute an endorsement or recommendation for use from these individuals or entities, nor does it constitute criticism for

similar ones not mentioned.

NDWRCDP DisclaimerThis work was supported by the National Decentralized Water

Resources Capacity Development Project (NDWRCDP) with funding provided by the U.S. Environmental Protection Agency through a

Cooperative Agreement (WPA No. X-830851-01-0) with Water Environment Research Foundation (WERF) in Alexandria, Virginia.

These materials have not been reviewed by the U.S. Environmental Protection Agency, NDWRCDP, or WERF. The contents of these

materials do not necessarily reflect the views and policies of the NDWRCDP, WERF, or the U.S. Environmental Protection Agency, nor does the mention of trade names or commercial products constitute

their endorsement or recommendation for use.

Disinfection, not Sterilization

• Goal of disinfection: – Inactivate pathogens or prevent their reproduction– May not get all of them

• Sterilization removes ALL LIFE

Chlorine Disinfection

• Chlorine is an oxidizer. • Destroys target organisms by oxidation of

cellular material.• Critical parameters for effectiveness

– Relatively clean effluent– Adequate contact time.

Chlorine Residuals

• Chlorine still present after the disinfection process

• Highly toxic to living organisms in receiving waters

• Dechlorination may be required if residual is > 0.2 mg/L

Caution: high risk

• Safety is critical– Exposure– Handling

• Corrosive• Unstable

Work safely!Work safely!

Tablet Chlorinators

Four Components:1. Chlorine tablets2. Tube that holds tablets3. Contact device4. Storage reservoir

Tablet Chlorinator

Typical Chlorine Tablets

• NOT A POOL TABLET!!!!!

Calcium hypochlorite

Dechlorination

• Tablet de-chlorinators– Units and tablets similar to chlorinators

• Sodium bisulfate

Inspection procedure

Form 7.5 Inspection Checklist: Disinfection Unit- Chlorine (DUC)

Caution: high risk

• Safety is critical– Exposure– Handling

1. Operation of chlorination system

a. Manufacturerb. Model #c. Disinfection unit appears in good condition

– Level– Watertight

Status

• Acceptable – Unit is intact, level

• Unacceptable– Unit is damaged, off level

2. Tablet chlorinationa. Chlorinator appears

operableb. Tablets in place (pull

cylinder)– Type of tablets

c. Tablets in contact with effluent

2. Tablet chlorination (cont.)

d. Chlorine residualFree Total• Testing method

– Chlorine meter– Colorimetric

Status

• Acceptable – Tablets in feeder and in contact with effluent– Chlorine residual present– Contact chamber is accessible and intact

• Unacceptable– No tablets in feeder or tablets not in contact with

effluent– No chlorine residual present– Contact chamber is inaccessible or damaged

3. Influent characteristics

a. Clear or Cloudy?

Check at Advanced treatment unitCollect a sample in a clear container

4. Tablet dechlorination

• Required?a. Dechlorinator appears operableb. Tablets in place

– Type

c. Tablets in contact with effluent d. Contact chamber appears operablee. Chlorine residual

Should be 0

Status

• Acceptable – Tablets in feeder and in contact with effluent– Correct tablets in use– No chlorine residual measured– Contact chamber is accessible and intact

• Unacceptable– No tablets in feeder or tablets not in contact with effluent– Wrong type of tablets– Chlorine residual present– Contact chamber is inaccessible or damaged

Questions?

Inspection of UV Disinfection Components

UV Disinfection

• Is NOT sterilization• Pathogen removal is the goal• Critical parameters for effectiveness

– Relatively clean effluent– Adequate contact time

Ultraviolet Light Disinfection Units

• Destroys microorganisms by altering their genetic material and / or retarding ability to reproduce

Caution: high risk

• Safety is critical– Exposure– Handling

Eye Protection

• Proper eye protection should be used when inspecting an UV disinfection unit.

• DO NOT look directly at the UV light with the power on.

Generating UV light

Ultraviolet Light Disinfection Units

• Electromagnetic energy (UV light) from source lamp is emitted into a chamber through which effluent passes

Form 7.6 Inspection Checklist: Disinfection Unit- Ultraviolet

(DUUL)

Inspection of UV Disinfection Unit

1. Power supply

a. Is unit gravity or pressure dosed?b. Manufacturer and model #c. Is power supplied to the unit?d. Is the UV lamp on?e. Is the electrical system free of corrosion or

damage?

1. Power supply (cont.)

f. Last ballast replacement date

Status

• Acceptable – Power to unit– Lamp on– No corrosion or damage to unit

• Unacceptable– No power– Lamp off– Unit is corroded or damaged

2. UV controls

a. Does the unit have a lamp intensity sensor?

b. If so, what was intensity reading?c. Alarm present?d. Alarm operating properly?

Status

• Acceptable – Intensity reading adequate– Alarm present and operable (visible and audible)

• Unacceptable– Inadequate intensity– Alarm not present or not operable (visible or

audible)

3. Contact chamber, lamp, and sleeve conditions

a. Evidence of damage or leakageb. Type of protective sleeve:

Quartz Teflon Other:___

c. Protective sleeve free of buildupd. Protective sleeve last replaced: ________

From ORC report

3. Contact chamber, lamp, and sleeve conditions (cont.)

e. Date lamp last replaced: ________ From ORC report

Status

• Acceptable – No damage to or leakage from unit– Reasonable build-up on sleeve

• Unacceptable– Unit damaged or leaking– Considerable buildup on sleeve

• Red flags

4. Influent characteristics

a. Clear or Cloudy?

Check at Advanced treatment unitCollect a sample in a clear container

5. Control Panel (may not be included)

a. Controls operating properly b. Is enclosure watertightc. Alarm test switch operating properlyd. At time of inspection, control switch was set to:

N.A.___________“Hand/Manual”__“Auto”_________

e. If auto, setting: Time On:_______ (min) Time Off:________ (min)

Status

• Acceptable – Water tight enclosure– Alarm switch operating– Control switch on AUTO

• Unacceptable– Enclosure not water tight– No alarm operation (audible or visible)

• Red flags

6. Housing

• Location:_________________a. Appears in good conditionb. Leaks/Cracks presentc. Excessive dust present

Status

• Acceptable – Housing appears in good condition– No leaks or cracks present– No excessive dust present

• Unacceptable– Housing damaged– Excessive dust

• Red flags

Inspections of UV Light Disinfection

Are there any questions ?