TPX™ and ElectrX™ shown to protect Tampa Bay from potential environmental crisis

Estuaries are a critically important habitat for coastal and open marine waters.  Located at the nexus between fresh and marine waters, these transitional environments serve as nurseries for most marine fish and shellfish and provide vital nesting and feeding habitats for many aquatic animals.

 Indeed, most fish and shellfish eaten in the United States, including salmon, herring, and oysters, complete at least part of their life cycles in estuaries. Tampa Bay is one of 28 bays located across the United States and supported as important natural resources through the National Estuary Program.  Tampa Bay is Florida’s largest estuary, covering approximately 254,700 acres, and supports a broad mosaic of habitats, including estuarine wetlands, freshwater wetlands, upland forests, seagrass beds, and submerged hard bottom. 

The Problem

In 1966 the Borden Chemical Company constructed a phosphate chemical processing plant (known as Piney Point) north of Palmetto Florida to commercially produce fertilizer. The chemical processing plant was originally built in close proximity to Port Manatee to take advantage of opportune worldwide shipment availability of the produced fertilizer. While logistically attractive, Piney Point is also within several kilometers of lower Tampa Bay, including pristine areas such as Bishop Harbor (which is part of the Terra Ceia Aquatic Preserve) in particular . The proximity of Piney Point to sensitive marine resources heightens the importance of environmental safeguards and water resource protections at the site. While the Piney Point plant was officially abandoned in 2001 by the Mulberry Corporation, the storage and management of acidic, nutrient-laden (enriched in both total phosphorus [TP] and inorganic nitrogen in the form of ammonia [NH4-N]) wastewater has continued to be an environmental concern. The various ponds on site currently hold approximately 600 million gallons of contaminated water. In 2006, HRK Holdings LLC acquired the property and subsequently assumed responsibility for site operations which included managing several key infrastructure components to control on-site water flow and storage. These components include two lined gypsum stacks (New North Gypstack [NGS-N] and New South Gypstack [NGS-S]), the lined process water sump (LPWS) pond, and a series of three seepage collection ditch networks. From an environmental perspective, mitigating the water contained in the three pond structures is thus the greatest concern at Piney Point.
The increasing likelihood that the on-site wastewater storage capacity of the Piney Point facility will become exhausted and necessitate releases of high nutrient-laden water into lower Tampa Bay has been an ongoing concern for regulators, environmental interests and other stakeholders in the Tampa Bay region for a couple of decades.  This concern has been heightened by several emergency releases from Piney Point, including the release of 10 million gallons of wastewater following Tropical Storm Gabrielle in 2001, and millions of gallons leaked into Bishop Harbor following ruptures to a lined gypstack in 2011.

Site map of the Piney Point facility showing the location of the LPWS, the NGS-N, and NGS-S, and other key hydrologic and facility features.

The Nclear Solution

In June 2017, Nclear, Inc. began a several month on-site pilot evaluation project to evaluate and demonstrate both the efficacy and feasibility of removing excess P and N concentrations in the process water stored at Piney Point to environmentally acceptable levels. This project was undertaken as a collaborative effort with HRK and the Florida Department of Environmental Protection (FDEP) as primary stakeholders to help evaluate a two-pronged approach towards reducing the high TP and NH4-N concentrations in the Piney Point wastewater at treatment volumes sufficiently high to both reduce the immediate risk of further surface water discharges, and potentially fully treat all ponded wastewater on-site. The first prong involved treating the Piney Point process water with TPX™, a proprietary synthetic mineral product developed by Nclear to primarily remove P from both water and wastewater. The second prong targeted the removal of N and compared the effectiveness of Nclear’s ElectrX™ technology, an electrochemical means to oxidize ammonia to form inert nitrogen gas (N2), with traditional air-stripping of ammonia gas. Minimum criteria for demonstrating successful treatment included reducing TP concentrations below 10 mg/L, and total nitrogen (TN) concentrations below 2 mg/L. In addition, because un-ionized ammonia (NH3) (which, if present, is a component of TN) is acutely toxic to a variety of aquatic organisms, the criteria for success also included a target concentration of ≤ 0.02 mg/L for un-ionized NH3.

Pilot Evaluation Results

The results from the compliance period monitoring during the pilot evaluation showed that the two-pronged approach implemented by Nclear was wholly successful with respect to meeting the target concentrations for the full suite of nutrient forms and pH (Table 1).
Table 1. Flow weighted concentrations for compliance parameters in the final treated effluent from the NGS-S, October 30 – November 5, 2017. Flow-weighted concentrations were calculated as a function of total daily flow treated during the first seven days of the compliance monitoring and daily effluent chemistry analyzed by FDEP and Benchmark as listed below, except for pH (measured on-site by Nclear).

Conclusions

TPX is an effective and efficient means for removal of these extremely high P concentrations, and also allows for the recovery of the P bound to TPX crystals.  In addition, ElectrX was demonstrated to be more effective and efficient for treating the high ammonia concentrations than air-stripping.  In addition to cost savings, ElectrX™ is more environmentally friendly because ammonia is converted to inert nitrogen gas ( N2), which is the primary component of the earth’s atmosphere.  Conversely, NH3 gas released into the atmosphere through air stripping and spray evaporation is both highly reactive with ambient aerosols and readily scavenged from the atmosphere by dew and rainfall (and can consequently redeposit in the Tampa Bay watershed).
Nclear estimates that utilizing its technologies to treat the pond water at Piney Point would allow for the recovery and recycling of 1.3 million pounds of phosphorus, and would prevent approximately 1.4 million pounds of ammonia from being released in the atmosphere and redeposited.
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