62-600.440. Disinfection Requirements

(1) All wastewater treatment facilities shall be designed and operated to meet the disinfection requirements in this section and the microbiological pollutants criteria contained in Chapter 62-302, F.A.C.

(2) The Department is aware of the possible harmful effects of chlorine used in conjunction with wastewater treatment and encourages the use of alternative disinfection methods.

(a) Criteria for establishing disinfection requirements for alternative disinfectants shall be accepted by the Department if the information provided by the permittee in the preliminary design or engineering report demonstrates that appropriate microbiological criteria will be met and provides reasonable assurance that public health is protected.

(b) Dechlorination shall be required by the Department to ensure that applicable water quality standards will be met and other appropriate reclaimed water or effluent limitations imposed pursuant to this chapter will be achieved.

(c) Maximum permissible residual levels in the reclaimed water or effluent immediately following chlorination and the need for dechlorination shall be established by the permittee and are subject to Department approval. Residual levels shall be established in the preliminary design or engineering report based on effects on the receiving surface or ground water and effects on reuse and land application systems.

(3) For ultraviolet disinfection, the impact of short-term interruptions in electrical service shall be evaluated in the preliminary design or engineering report along with the possible need for an uninterrupted power supply to ensure reliable and effective disinfection.

(4) Treatment performance requirements for disinfection are specified below for discharges from all facilities. Applicability of the requirements shall be as contained in Chapter 62-610, F.A.C., for reuse and land application systems; Rule 62-600.540, F.A.C., for ground water disposal by underground injection; Chapter 62-610, F.A.C., for ground water recharge and aquifer storage and recovery projects using injection wells; Rule 62-600.510, F.A.C., for surface water discharges (excluding coastal and open ocean waters); Rule 62-600.520, F.A.C., for coastal and open ocean waters; Rule 62-611.600, F.A.C., for wetland discharges; and subsection 62-600.100(2), F.A.C., for septic systems and other closed-tank wastewater treatment systems permitted by the Department.

(5) Basic disinfection.

(a) Facilities required to provide basic disinfection shall meet the following criteria (using either MF or equivalent MPN methods):

1. The arithmetic mean of the monthly geometric means of the fecal coliform values collected during an annual period shall not exceed 200 per 100 mL of reclaimed water or effluent sample,

2. The geometric mean of the fecal coliform values for a minimum of 10 samples of reclaimed water or effluent, each collected on a separate day during a period of 30 consecutive days (monthly), shall not exceed 200 per 100 mL of sample,

3. No more than 10% of the samples collected during a period of 30 consecutive days shall exceed 400 fecal coliform values per 100 mL of sample; and,

4. Any one sample shall not exceed 800 fecal coliform values per 100 mL of sample.

(b) Regardless of the number of samples collected, the monthly geometric means of the fecal coliform values shall be calculated and reported on the Discharge Monitoring Report, and the arithmetic mean shall be calculated using the monthly geometric mean.

(c) Where chlorine is used for disinfection, a total chlorine residual of at least 0.5 mg/L shall be maintained after at least 15 minutes contact time at the peak hourly flow. Higher residuals or longer contact times shall be provided to meet the criteria for basic disinfection as described in paragraph 62-600.440(5)(a), F.A.C. The chlorine residual and contact time selected shall be justified in the preliminary design or engineering report. Rapid and uniform mixing shall be provided.

(6) High-level disinfection.

(a) Except as provided in paragraphs 62-600.440(6)(e) and (f), F.A.C., facilities required to provide high-level disinfection shall meet the following criteria (using MF or equivalent MPN methods):

1. Over a 30 day period (monthly), 75% of the fecal coliform values shall be below the detection limits,

2. Any one sample shall not exceed 25 fecal coliform values per 100 mL of sample; and,

3. Any one sample shall not exceed 5.0 mg/L of TSS at a point before application of the disinfectant.

(b) Where chlorine is used for disinfection, a total chlorine residual of at least 1.0 mg/L shall be maintained at all times. The minimum acceptable contact time shall be 15 minutes at the peak hourly flow. Higher residuals or longer contact times shall be provided to meet the criteria for high-level disinfection as described in paragraphs 62-600.440(6)(a) and (c), F.A.C. The chlorine residual and contact time selected shall be justified in the preliminary design or engineering report. Rapid and uniform mixing shall be provided.

(c) Where chlorine is used for disinfection, new or expanded treatment facilities shall use the following design criteria for total chlorine residual and contact time:

1. For a reclaimed water or effluent containing 1,000 fecal coliforms, or less, per 100 mL, before disinfection, the product of the total chlorine residual used for design (expressed in mg/L) and the contact time at peak hourly flow (expressed in minutes) shall be at least 25.

2. For a reclaimed water or effluent containing greater than 1,000 and up to and including 10,000 fecal coliforms per 100 mL, before disinfection, the product of the total chlorine residual used for design (expressed in mg/L) and the contact time at peak hourly flow (expressed in minutes) shall be at least 40.

3. For a reclaimed water or effluent containing greater than 10,000 fecal coliforms per 100 mL, before disinfection, the product of the total chlorine residual used for design (expressed in mg/L) and the contact time at peak hourly flow (expressed in minutes) shall be at least 120.

(d) Alternate combinations of chlorine residuals and contact times used to meet the criteria in paragraph 62-600.440(6)(c), F.A.C., shall be accepted by the Department if justified in the preliminary design or engineering report.

(e) The requirements in subsection 62-600.440(7), F.A.C., shall serve as the high-level disinfection criteria if all of the following conditions are met:

1. Wetlands are used for the discharge or treatment of reclaimed water or effluent,

2. Public access to the wetlands is restricted; and,

3. The reclaimed water produced is not used in a reuse system permitted under Part III or V of Chapter 62-610, F.A.C.

(f) The requirements in subsection 62-600.440(7), F.A.C., shall serve as the high-level disinfection criteria if all the following conditions are met:

1. The discharge is to surface waters,

2. The discharge is serving as a back-up disposal system associated with a reuse system permitted under Part III or V of Chapter 62-610, F.A.C.,

3. The discharge is not subject to regulation by subsection 62-600.510(2) or (3), F.A.C., as a discharge to Class I waters or waters contiguous to or tributary to Class I waters; and,

4. The discharge is not subject to regulation by subsection 62-600.510(7), F.A.C., as a discharge to surface waters which are directly connected to Class F-I, G-I, or G-II ground water.

(7) Intermediate disinfection.

(a) Facilities required to provide intermediate disinfection shall meet the following criteria (using either MF or equivalent MPN methods):

1. The arithmetic mean of the monthly medians of the fecal coliform values collected during an annual period shall not exceed 14 per 100 mL of reclaimed water or effluent sample,

2. The median value of the fecal coliform values for a minimum number of 10 samples of reclaimed water or effluent, each collected on a separate day during a period of 30 consecutive days (monthly), shall not exceed 14 per 100 mL of sample,

3. No more than 10% of the samples collected during a period of 30 consecutive days shall exceed 43 fecal coliform values per 100 mL of sample; and,

4. Any one sample shall not exceed 86 fecal coliform values per 100 mL of sample.

(b) Regardless of the number of samples collected, the monthly medians of the fecal coliform values shall be calculated and reported on the Discharge Monitoring Report, and the arithmetic mean shall be calculated using the monthly medians.

(c) Where chlorine is used for disinfection, a total chlorine residual of at least 1.0 mg/L shall be maintained after at least 15 minutes contact time at the peak hourly flow. Higher residuals or longer contact times shall be provided to meet the criteria for intermediate disinfection as described in paragraph 62-600.440(7)(a), F.A.C. The chlorine residual and contact time selected shall be justified in the preliminary design or engineering report. Rapid and uniform mixing shall be provided.

(8) Low-level disinfection.

(a) Facilities required to provide low-level disinfection, allowable under highly controlled conditions for overland flow systems as specified in part VI of chapter 62-610, F.A.C., shall meet an effluent criteria of not more than 2,400 fecal coliform values per 100 mL of sample.

(b) The effluent or reclaimed water discharged from an overland flow system shall meet the applicable microbiological standards for surface water and groundwater specified in Chapters 62-302 and 62-520, F.A.C.

Rulemaking Authority 403.051, 403.061, 403.086, 403.087, 403.088 FS. Law Implemented 403.021, 403.051, 403.061, 403.062, 403.085, 403.086, 403.087, 403.088 FS. History–New 11-27-89, Amended 1-30-91, 6-8-93, Formerly 17-600.440, Amended 12-24-96, 2-8-16, 9-27-21.