Pinellas County South Cross Bayou Water Reclamation Facility

FACILITY BASIC INFORMATION

• Plant Name: South Cross Bayou Water Reclamation Facility (SCBWRF)
• Location: 7401 54th Avenue North, St. Petersburg, FL 33709
• Operating Authority: Pinellas County Utilities (PCU)
• Design Capacity: 33.0 MGD (Annual Average Daily Flow)
• Current Average Flow: ~22-24 MGD
• Population Served: Approximately 300,000 residents
• Service Area: Southern Pinellas County (Pinellas Park, Kenneth City, Seminole, and unincorporated areas)
• Receiving Water Body: Cross Bayou Canal / Boca Ciega Bay (Aquatic Preserve)
• NPDES Permit Number: FL0021750
• Year Commissioned: 1960s (Original); Major AWT Expansion in early 1990s

1. INTRODUCTION

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The South Cross Bayou Water Reclamation Facility (SCBWRF) serves as the cornerstone of wastewater infrastructure for the southern portion of Pinellas County, Florida. As the largest advanced wastewater treatment facility operated by Pinellas County Utilities, SCBWRF is permitted for an Annual Average Daily Flow (AADF) of 33.0 million gallons per day (MGD). The facility is a critical component of the region’s integrated water resources management strategy, operating as a zero-discharge facility during dry weather by distributing 100% of its effluent to the South County Reclaimed Water System.

Distinguished by its dual role in water reclamation and resource recovery, SCBWRF houses a regional biosolids management facility that processes sludge into Class AA fertilizer pellets, marketed under the brand “Green Squared.” Operating under strict Advanced Waste Treatment (AWT) standards due to its discharge potential into the environmentally sensitive Boca Ciega Bay Aquatic Preserve, the facility represents a benchmark in nutrient removal technology and circular economy principles within the Florida wastewater sector.

2. FACILITY OVERVIEW

A. Service Area & Coverage

The SCBWRF service area encompasses the densely populated southern Pinellas peninsula. It receives flow from a complex collection system serving the municipalities of Pinellas Park, Kenneth City, portions of Seminole, and extensive unincorporated areas of St. Petersburg. The collection system feeding the plant includes over 50 master pump stations and hundreds of miles of gravity mains and force mains. Due to the high water table and aging infrastructure in the region, the facility must manage significant wet-weather inflow and infiltration (I&I) challenges.

B. Operational Capacity

The facility is designed and permitted for a capacity of 33.0 MGD, with a peak hydraulic capacity exceeding 60 MGD to handle tropical storm surges. Historically, the plant operates at approximately 65-75% of its permitted capacity, treating an average of 22 to 24 MGD. This operational headroom is critical for managing seasonal population fluctuations (tourism and “snowbirds”) and sudden hydraulic loading during Florida’s wet season.

C. Discharge & Compliance

SCBWRF operates under a Florida Department of Environmental Protection (FDEP) National Pollutant Discharge Elimination System (NPDES) permit. The facility is classified as an Advanced Waste Treatment (AWT) plant. Its primary objective is the production of high-quality reclaimed water for irrigation. During periods of low demand (wet weather), excess treated effluent is discharged to the Cross Bayou Canal, which flows into Boca Ciega Bay. Due to the designation of the receiving waters as an Aquatic Preserve and Outstanding Florida Water, the plant is held to stringent nutrient limits, typically 5 mg/L BOD, 5 mg/L TSS, 3 mg/L Total Nitrogen, and 1 mg/L Total Phosphorus.

3. TREATMENT PROCESS

The SCBWRF utilizes a multi-stage Advanced Waste Treatment (AWT) process designed to achieve biological nutrient removal (BNR) and high-level disinfection suitable for public access reuse.

A. Preliminary Treatment

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Influent wastewater enters the headworks where it passes through mechanical bar screens to remove large debris, rags, and plastics. Following screening, the flow enters vortex grit removal systems where sand and heavier inorganics settle out via centrifugal force. The removed grit and screenings are washed, compacted, and transported to the county landfill. Odor control at the headworks is a priority, utilizing chemical scrubbers (typically packed towers with sodium hypochlorite and caustic soda) to neutralize hydrogen sulfide.

B. Primary Treatment

Flow proceeds to rectangular primary clarifiers. Here, the velocity of the wastewater is reduced, allowing settleable organic solids to drop to the bottom as primary sludge, while fats, oils, and grease (FOG) are skimmed from the surface. The primary sludge is pumped directly to the solids handling facility for thickening and digestion. This stage typically removes 30-50% of suspended solids and BOD, reducing the load on the biological systems.

C. Secondary Treatment (Biological)

The core of the treatment process involves **Activated Sludge** with Biological Nutrient Removal (BNR). The facility utilizes aeration basins configured for nitrification and denitrification.
Microorganisms digest organic matter and convert ammonia-nitrogen into nitrate (nitrification) and subsequently into nitrogen gas (denitrification) through anoxic and aerobic zones. Oxygen is supplied via fine-bubble diffusion systems or mechanical surface aerators, depending on the specific train configuration. Following aeration, the mixed liquor flows to secondary clarifiers where the biomass settles. A portion is returned to the aeration basins as Return Activated Sludge (RAS), while excess biomass is removed as Waste Activated Sludge (WAS).

D. Tertiary Treatment (Filtration & Denitrification)

To meet the strict 3.0 mg/L Total Nitrogen limit required for AWT discharge, the facility employs **Deep Bed Denitrification Filters**. Methanol is often added as a carbon source prior to filtration to drive the conversion of remaining nitrate to nitrogen gas within the filter media. These gravity filters also serve as the final polishing step for suspended solids removal, ensuring low turbidity essential for effective disinfection.

E. Disinfection

The filtered effluent undergoes high-level disinfection using **Chlorine** (gas or sodium hypochlorite solution). The water flows through chlorine contact chambers with sufficient residence time to ensure pathogen inactivation required for Part III public access reclaimed water. While many modern plants are moving to UV, chlorine remains favored here to provide a residual within the extensive reclaimed water distribution network, preventing biological regrowth in the pipes.

F. Solids Handling & Pelletization

SCBWRF is unique for its on-site **Biosolids Pelletizer Facility**.

• Thickening/Dewatering: Primary and waste activated sludge are thickened and dewatered using centrifuges.
• Drying: The dewatered cake enters a rotary drum thermal drying system fueled by natural gas/biogas.
• Pelletization: The heat kills pathogens and dries the material to >90% solids, creating Class AA EQ (Exceptional Quality) fertilizer pellets.
• Reuse: These pellets are sold commercially under the brand “Green Squared,” diverting tons of waste from landfills and returning nutrients to the soil.

G. Process Control

The entire facility is monitored via a comprehensive SCADA (Supervisory Control and Data Acquisition) system. Operators monitor dissolved oxygen, pH, ORP (Oxidation-Reduction Potential), and tank levels in real-time. The facility includes an on-site laboratory certified for process control and compliance testing.

4. INFRASTRUCTURE & FACILITIES

A. Physical Plant

The SCBWRF occupies a significant footprint in a mixed industrial/residential zone. Key structures include the Headworks building, multiple batteries of aeration basins and clarifiers, the tertiary filter complex, the chlorine contact chambers, and the prominent biosolids drying building. The site also houses administration offices, the central laboratory, and maintenance workshops.

B. Reclaimed Water System

The facility feeds the **South County Reclaimed Water System**, one of the most extensive reuse networks in the country. Large high-service pumps distribute water to residential lawns, golf courses, parks, and commercial properties. A massive 20-million-gallon storage tank (and additional off-site storage) allows the facility to buffer diurnal flow variations and store water during wet weather for use during dry periods.

C. Odor Control

Given the plant’s proximity to residential neighborhoods, odor control is a critical infrastructure component. The facility employs a multi-stage approach, including covering primary treatment tanks and utilizing high-capacity chemical scrubbers (wet scrubbers) and biotrickling filters to treat foul air extracted from the headworks and sludge processing areas.

5. RECENT UPGRADES & MAJOR PROJECTS

Pinellas County Utilities continuously invests in SCBWRF to maintain compliance and asset reliability. Major recent and ongoing projects include:

SCBWRF Denitrification Filter Rehabilitation (2019-2022)

• Project Scope: Rehabilitation of the deep bed denitrification filters, including replacement of underdrains, media, and backwash pumps. Installation of new air scour blowers and controls.
• Budget: ~$15 Million
• Project Drivers: Aging infrastructure (original filters nearing end of life) and the necessity to maintain strict nitrogen removal limits for Boca Ciega Bay discharge.
• Technical Highlights: Implementation of improved media designs to optimize nitrate removal efficiency and reduce backwash frequency.

Biosolids Facility Dryer Replacement & Upgrades (Ongoing/Recent)

• Project Scope: Replacement of rotary drum dryers, furnace components, and pellet cooling systems. Upgrades to safety systems for dust handling (explosion prevention).
• Budget: ~$20 Million+
• Project Drivers: The existing dryers had reached the end of their useful service life. The project ensures the continued production of Class AA pellets.
• Results: Increased reliability of the solids handling train and improved energy efficiency of the thermal drying process.

Electrical Distribution System Improvements

• Project Scope: Replacement of main switchgear, motor control centers (MCCs), and emergency generators.
• Project Drivers: Resiliency against tropical storms and grid instability. Ensuring 100% backup power capacity for all critical process units.

Upcoming Projects (2024-2027): The Capital Improvement Plan (CIP) includes provisions for headworks screening improvements and clarifier mechanism replacements to address corrosion issues common in Florida’s humid, saline environment.

6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

A. Permit Requirements

The facility operates under FDEP Permit FL0021750. As an AWT facility discharging to an Aquatic Preserve, it must meet limits significantly stricter than federal secondary standards:

• BOD (Annual Avg): 5.0 mg/L
• TSS (Annual Avg): 5.0 mg/L
• Total Nitrogen (TN): 3.0 mg/L
• Total Phosphorus (TP): 1.0 mg/L

B. Compliance History

SCBWRF generally maintains a strong compliance record. Occasional challenges have historically been related to wet-weather blending events during hurricanes or mechanical upsets in the biosolids train. However, the consistent operation of the denitrification filters allows the plant to reliably meet the 3.0 mg/L nitrogen limit, protecting the seagrass beds of Boca Ciega Bay from nutrient-induced algal blooms.

7. OPERATIONAL EXCELLENCE

A. Staffing & Certification

The facility is staffed 24 hours a day, 365 days a year. Florida law requires the lead operator to hold a Class A Wastewater Operator License. The staff comprises licensed operators, industrial electricians, mechanics, and instrumentation technicians. Pinellas County maintains a robust training program to encourage lower-level operators to achieve Class A certification.

B. Technology & Innovation

Pinellas County is a leader in water reuse. SCBWRF was among the first in the region to implement large-scale biosolids pelletization, turning a waste liability into a revenue-generating commercial product. The integration of the reclaimed water system with the treatment plant—utilizing the distribution system as a “purple pipe” reservoir—demonstrates advanced integrated water management.

8. CHALLENGES & FUTURE PLANNING

A. Current Challenges

• Inflow and Infiltration (I&I): During tropical storm events, flow to the plant can spike dramatically, stressing hydraulic capacity and diluting the biological mass.
• Aging Infrastructure: Like many plants built in the 60s/70s, SCBWRF faces corrosion of concrete and steel structures, requiring constant rehabilitation.
• Grit Removal: Florida’s sandy soil leads to high grit loading, which causes abrasion on pumps and accumulation in digesters.

B. Future Planning

The Pinellas County Wastewater/Water Master Plan outlines a strategy for the next 20 years. Key initiatives for SCBWRF include hardening the facility against sea-level rise and storm surge (hardening critical electrical gear), optimizing energy consumption through VFD upgrades, and potentially exploring Potable Reuse technologies in the distant future as aquifer supplies tighten.

9. COMMUNITY & REGIONAL IMPACT

The economic impact of SCBWRF is substantial. By providing high-quality reclaimed water to thousands of residents and businesses, the facility offsets millions of gallons of potable water demand daily, preserving the Floridan Aquifer. The “Green Squared” fertilizer program reduces the county’s landfill costs and provides a sustainable nutrient source for Florida agriculture. Furthermore, the facility’s strict adherence to nutrient limits is vital for the health of the local tourism economy, which relies on clean water in the Gulf of Mexico and Boca Ciega Bay.

10. TECHNICAL SPECIFICATIONS SUMMARY

11. RELATED FACILITIES

SCBWRF operates in conjunction with the William E. Dunn Water Reclamation Facility, which serves the northern portion of Pinellas County. The two facilities share management strategies and biosolids handling protocols. Additionally, SCBWRF is supported by numerous master pump stations throughout the peninsula that direct flow to the headworks.

12. FAQ SECTION

Technical Questions

1. What is the specific nutrient removal mechanism at SCBWRF?
The facility uses a combination of biological anoxic/aerobic zones in the aeration basins for nitrification/denitrification, followed by deep bed denitrification filters with methanol addition to polish nitrogen levels to below 3.0 mg/L.

2. Does SCBWRF produce energy from biogas?
The facility generates biogas during solids processing, which is primarily used to fuel the thermal dryers for the pelletization process, reducing natural gas dependency.

3. How does the plant handle peak wet weather flows?
The facility has excess hydraulic capacity and utilizes on-site and off-site storage tanks (20MG+) to equalize flow. In extreme emergencies, the permit allows for specific blending protocols to protect biological biomass.

Public Interest Questions

4. Can I buy the fertilizer produced at the plant?
Yes. The “Green Squared” fertilizer pellets produced at SCBWRF are available for commercial and retail purchase, meeting Class AA safety standards.

5. Why is the water called “Reclaimed” and not “Wastewater”?
The effluent meets Part III public access reuse standards, meaning it is highly treated, filtered, and disinfected, making it safe for irrigation and contact, though not for drinking.

6. Does the plant smell?
While wastewater treatment inherently involves odors, SCBWRF employs advanced chemical scrubbers and covers major process tanks to minimize odors. Occasional odors may occur during maintenance or extreme weather.