Photolytic Destruction Technology Demonstration at NAS North Island, Site 9, San Diego, California

Site Name:

Naval Air Station North Island


San Diego, CA

Period of

10/12/97 - 10/18/97 - startup
10/24/97 - 1/8/98 - parametric tests
1/17/98 - 2/6/98 - steady-state tests




Process Technologies Inc (PTI)

Photolytic Destruction

- Fluidized bed concentration unit, including an absorber, desorber, and chilled-water condenser
- Photolytic destruction unit (PDU), consisting of photolytic reactors and a wet scrubber

Cleanup Authority:

Regulatory Point of Contact:
Information not provided
Additional Contact:
Naval Facilities Engineering Service
1100 23rd Avenue
Port Hueneme, CA 93043-4301

Naval Facilities Engineering Service
1100 23rd Avenue
Port Hueneme, CA 93043-4301

Volatile Organic Compounds (VOCs)

- Halogenated and non-halogenated VOCs, including 1,2-dichloroethene, trichloroethene, tetrachloroethene, toluene

Waste Source:
Disposal of liquid chemical waste

Type/Quantity of Media Treated:
Soil vapor - estimated 1,151 lbs of VOCs

Purpose/Significance of Application:
Demonstrate the effectiveness of PTI's photolytic destruction units in treating VOC-contaminated vapor from an SVE system

Regulatory Requirements/Cleanup Goals:
The goal of the demonstration was to obtain cost and performance data on PTI's system and to make comparisons to other treatment technologies demonstrated at the site. The objectives included determining the total average destruction and removal efficiencies of the system, developing cost data for a 3000 scfm PTI system, and characterizing and quantifying secondary waste streams and residuals.

- The PTI system removed VOCs in the SVE off-gas to levels below the maximum allowable emissions of 25 ppmv. The average total DRE for VOCs was 95%.
- The report provides more detailed information comparing PTI's technology performance to other treatment technologies.

Cost Factors:
- The total demonstration cost was $93,726, including work plan, moblilization/demobilization , site work, liquids collection and containment, treatment, monitoring, sampling and analysis, and residuals disposal. The report included a detailed cost breakout.
- The estimated unit cost to treat the SVAE off-gas at NAS Nroth Island's Site 9, using a 3000 scfm system, is $3.77 per lb of VOC.

NAS North Island Site 9, the Chemical Disposal Area, was used for the disposal of liquid chemical wastes from the 1940s to the 1970s. A wide range of contaminants were detected in soils at the site including VOCs, semi-volatile organic compounds (SVOCs), petroleum hydrocarbons, PCBs, and metals. As part of a non-time-critical removal action, an SVE system has been installed at the site in Areas 1 and 3 to remove and treat VOCs. As part of the Navy Environmental Leadership Program, PTI was selected to demonstrate their Photolytic Destruction Technology for NAS North Island, Site 9 and to make comparisons with other commercially-available treatment technologies. The PTI system was demonstrated with the existing SVE system at the site, specifically treating soil vapor from Area 3 wells. The demonstration was conducted in two phases. Phase 1 involved parametric testing to establish the optimal process configuration, and Phase 2 which involved Steady-State Testing using the system configuration from Phase 1.

The PTI system consisted of a fluidized bed concentration unit and a PDU. The three main components of the concentration unit were: an adsorber to develop a fluidized bed of adsorbent beads to extract organic vapors from the SVE vapor stream; a desorber containing a steam-heated heat exchanger that warms the adsorbent to 300 °F to evaporate the VOCs from the loaded adsorbent beads; and a chilled-water condenser to remove the water vapor and non-halogenated organics from the concentrated vapor. The PDU consisted of two main components: two photolytic reactors capable of treating up to 5 acfm each of concentrated VOC vapor and a wet scrubber to remove any trace amounts of acidic by-products from the photolytic reactor stream. The PTI system used for the demonstration was designed to treat 500 scfm of vapor from the SVE system (which was rated at 3000 scfm) and to remove a minimum of 3.6 lbs/hr of VOCs. The maximum flow rate during the demonstration was 440 scfm and the average amount of VOCs removed was 1.22 lbs/hr. The results of the Steady-State operations showed an average DRE for the PTI system of 95.44%, with the PDU alone achieving an overall DRE of 97%. In addition, the PTI system was found to be relatively quick to install and was operational 89% of the time. As a result of the demonstration, PTI recommended several design modifications to enhance system performance including redesigning the weather seals in the concentration unit to prevent rainwater and humidity from entering the adsorber, which was the primary operational problem encountered with this component during the demonstration. In addition, PTI recommended evaluating the performance of different adsorbent materials to determine which offers the most cost effective removal efficiencies. The report also presents detailed information on secondary wastes and residuals generated during the demonstration as well as a detailed discussion of operational problems encountered during the demonstration.

The total demonstration cost was $93,726, including work plan, mobilization/demobilization, site work, liquids collection and containment, treatment, monitoring, sampling and analysis, and residuals disposal. The report included a detailed cost breakout. The data from the demonstration were used to estimate the cost of implementing a 3000 scfm PTI system at NAS North Island Site 9. The estimated unit cost for such a system was $3.77 per lb of VOC treated. According to PTI, the commercialization of the technology over the next few years will lower the treatment costs further.