Inspection of Disinfection Components NC Certified Subsurface Systems Inspector Training School

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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!

Tablet Chlorinators Four Components: 1.Chlorine tablets 2.Tube that holds tablets 3.Contact device 4.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. Manufacturer b. Model # c. Disinfection unit appears in good condition – Level – Watertight

Status Acceptable – Unit is intact, level Unacceptable – Unit is damaged, off level

2. Tablet chlorination a. Chlorinator appears operable b. Tablets in place (pull cylinder) – Type of tablets c. Tablets in contact with effluent

2. Tablet chlorination (cont.) d. Chlorine residual  Free  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 unit Collect a sample in a clear container

4. Tablet dechlorination Required? a. Dechlorinator appears operable b. Tablets in place – Type c. Tablets in contact with effluent d. Contact chamber appears operable e. 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 leakage b. Type of protective sleeve:  Quartz  Teflon  Other:___ c. Protective sleeve free of buildup d. 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 unit Collect a sample in a clear container

5. Control Panel (may not be included) a.Controls operating properly b.Is enclosure watertight c.Alarm test switch operating properly d.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 condition b.Leaks/Cracks present c.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 ?