Water supply management is essential for public health and environmental sustainability. The Peace River Manasota Regional Water Supply Authority has emerged as a leader in innovative water treatment methods, including the use of Powdered Activated Carbon Treatment (PACT), to address various challenges associated with water quality. This article delves into the Authority’s history, operational strategies, awards, and the significant issues it faces, particularly concerning taste and odor challenges in drinking water.

The Role of the Peace River Manasota Regional Water Supply Authority

Overview and Operations

The PRMRWSA operates a surface water treatment plant that draws water from the Peace River, treating it to meet stringent drinking water standards. The facility has a treatment capacity of approximately 31 million gallons per day, ensuring a reliable supply of potable water to its service area.

Awards and Recognition

The Authority’s commitment to excellence has been recognized through numerous awards, including:

2023 Plant Operations Excellence Award from the Florida Department of Environmental Protection

2023 Most Improved Water Treatment Plant by the Florida Section AWWA

Outstanding Water Treatment Plant Award from the Florida Section AWWA in 2021, 2018, and 2016

2020 Sustainable Water Utility Management Award from the Association of Metropolitan Water Agencies (AMWA)

Six AWWA Best of the Best Tap Water Taste Contest regional and state awards in Florida since 2004

These accolades highlight the Authority’s dedication to maintaining high standards in water quality and operational efficiency.

Challenges in Water Quality Management

Taste and Odor Issues

One of the primary challenges faced by the PRMRWSA is managing taste and odor problems in drinking water. These issues are prevalent in Florida due to the high total organic content (TOC) found in its rivers, which results from diverse ecosystems, including swamps, forests, wetlands, and prairies. The runoff from these areas leads to surface water rich in organic matter, causing undesirable taste and odor events that conflict with the Authority’s aesthetic standards for finished drinking water.

Key Compounds Affecting Water Quality

The organic compounds primarily responsible for taste and odor issues in drinking water are 2-methylisoborneol (MIB) and Geosmin:

MIB: Known for its musty smell, MIB is produced in biofilms on rocks, aquatic plants, and sediment.

Geosmin: This compound has an earthy smell and is typically produced by planktonic cyanobacteria.

Humans can detect Geosmin at concentrations as low as 10 parts per billion (µg/L) and MIB at 5 parts per billion (µg/L), making them significant concerns for water utilities.

Public Impact of Taste and Odor Problems

Beyond aesthetic concerns, unpleasant tastes and odors can create public anxiety regarding water quality and safety, potentially eroding trust in the water utility. The PRMRWSA recognizes the importance of addressing these issues to maintain public confidence in its services.

Managing Taste and Odor: Strategies and Solutions

Temperature-Driven Spikes

Like many water utilities, the PRMRWSA experiences temperature-driven spikes in MIB and Geosmin levels. The likelihood of these spikes increases when water temperatures exceed 75°F. Predicting individual spikes remains challenging, necessitating a rapid dosing response upon detecting elevated levels. Recently, these spikes have lasted longer, requiring more consistent dosing strategies.

Monitoring and Forecasting

To effectively manage these challenges, the Authority is actively monitoring raw influent concentration levels and environmental conditions. This involves developing a forecasting model through a year-long study that incorporates various data points to identify conditions leading to spikes. To enhance detection, the plant has increased its sampling frequency from once a month in winter to as often as three times a week in spring as temperatures rise.

Mitigating MIB and Geosmin with PACT

To address MIB and Geosmin, the PRMRWSA employs Powdered Activated Carbon (PAC) from Jacobi Carbons (AquaSorb CB1-MW). Through controlled and optimized dosing, the Authority successfully reduces taste and odor compounds to non-detectable levels, ensuring high-quality drinking water for its customers. This activated carbon is sourced from a manufacturer that adheres to rigorous internal laboratory testing and quality control, providing greater consistency and reliability compared to products from less stringent suppliers.

On-Site Testing and Dosing Optimization

The PRMRWSA has invested in on-site testing equipment to obtain near real-time water quality data, allowing for immediate and accurate dosing. This approach enables dosing based on current MIB and Geosmin levels rather than relying on outdated samples sent for testing.

Procurement Process Enhancements

Prior to 2017, the facility required activated carbon media to be AWWA B604 approved and NSF-61 certified, with a minimum iodine level of 500. This standard allowed lower-quality products to compete with higher-quality ones based solely on price. In one instance, a low-quality product caused significant maintenance issues during contaminant spikes, leading to ineffective normal dosing rates and increased costs.

Since 2017, the facility has awarded its activated carbon contract based on a combination of price and performance, with minimum standards such as an iodine number of 800 and a specific pH range.

This ensures the selection of the highest quality carbon at the best price. To verify performance, the PRMRWSA sends supplier samples to an independent lab, along with actual intake water from the Peace River, to simulate field conditions and obtain unbiased performance reports.

The Role of Powdered Activated Carbon Treatment (PACT)

Overview of PACT

Powdered Activated Carbon Treatment (PACT) is a wastewater technology that involves adding powdered activated carbon to anaerobic or aerobic treatment systems. The carbon adsorbs recalcitrant compounds that are not readily biodegradable, effectively reducing the chemical oxygen demand (COD) of the wastewater and removing toxins. Additionally, the carbon acts as a “buffer” against the effects of toxic organics present in the wastewater.

Synergistic Treatment Process

In a PACT system, biological treatment and carbon adsorption are combined into a single, synergistic treatment step. This integration results in significant cost reductions compared to traditional activated sludge and granular carbon treatment options. The inclusion of powdered activated carbon stabilizes biological systems against upsets and shock loading, controls color and odor, and may lower disposal costs while effectively removing soluble organics.

Aerobic Treatment System

In an aerobic treatment system, the influent first enters an aeration tank where powdered carbon is added, contributing to the mixed liquor suspended solids. After aeration, the treated wastewater and carbon-biomass slurry are allowed to settle. In scenarios requiring complete solids separation, a Membrane Bioreactor (MBR) may replace the clarifier.

Following treatment, a portion of the carbon and biomass slurry is wasted for solids handling. Thanks to the powdered activated carbon, the sludge settles, thickens, and dewaters more efficiently than in conventional activated sludge processes. The resulting solids can be disposed of as a slurry, dewatered into a compact, stable cake, or pumped to a wet air oxidation unit for further processing to regenerate the carbon and destroy biological solids.

Global Adoption of PACT

Currently, there are over 100 PACT systems worldwide. Many of these systems have been retrofitted to existing conventional activated sludge processes to comply with stringent effluent requirements. Recent years have seen several PACT systems established in China due to higher treatment regulations for difficult-to-treat industrial wastewaters. PACT systems are also employed to meet bioassay and toxicity requirements and facilitate water reuse

Conclusion

The Peace River Manasota Regional Water Supply Authority stands as a testament to effective water supply management and innovative treatment technologies. Through its commitment to excellence, the Authority has successfully navigated the challenges of taste and odor issues in drinking water while ensuring compliance with health standards.

The implementation of Powdered Activated Carbon Treatment (PACT) has proven instrumental in enhancing water quality and maintaining public trust. As the Authority continues to evolve and adapt to changing environmental conditions, its dedication to providing safe, high-quality drinking water remains unwavering, securing a vital resource for the communities it serves.

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