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A Look into CytoCulture's History: Contract Bioremediation Services

CytoCulture is an environmental biotechnology firm based in Point Richmond providing bioremediation services and support. The company uses its own proprietary bioreactor technology and laboratory selected strains of aerobic bacteria to biodegrade a wide range of hydrocarbon contaminants in soil and groundwater. Teaming with affiliated environmental engineering firms, both in the United States and internationally, CytoCulture provides contract bioremediation services for a wide variety of clients and situations, including:

• Remedial Action Plan Preparation and Permitting
• Laboratory and Pilot Scale Biotreatability Studies
• Fabrication of Bioreactor Systems
• Bioremediation of Contaminated Groundwater
• Bioremediation of Excavated Soil
• In situ Groundwater Bioremediation
• In situ Bio-venting of soil

In addition, the firm maintains its own microbiology laboratory, offering biotreatablility studies and laboratory support for other bioremediation / biotechnology projects.

Permitting and Regulatory Affairs

An ongoing dialogue with regulatory agencies is essential to the success of any bioremediation project. Through previous project experience, the California Environmental Protection Agency, the three Regional Water Quality Control Boards (SF Bay, North Coast and Los Angeles), the county Environmental Health Departments, and the local regulatory districts are all familiar with CytoCulture's bioremediation technology. Air Quality Management Districts in the South Coast and Bay Area have approved past projects. CytoCulture has also collaborated with the Cal-EPA Alternative Technology Section (Sacramento) to promote the development and application of bioremediation state wide. Several CytoCulture projects have set regulatory precedents for soil or groundwater bioremediation. CytoCulture is currently petitioning the California EPA to list CytoCulture's proprietary microbiological laboratory techniques as Certified Environmental Technology.

CytoCulture Products

CytoCulture's major products are proprietary bioreactors used to generate site-specific, hydrocarbon-degrading aerobic bacteria. The bioreactors use controlled aeration to maintain high density bacterial cultures and are available with working capacities from 500 to 16,000 gallons. These bioreactors can be fabricated on site internationally using local materials.

CytoCulture typically designs and builds complete bioremediation systems made entirely of chemical-resistant plastic, thus keeping these units inexpensive relative to conventional steel water treatment systems. Furthermore, the components are easy to ship and assemble into modular configurations for site-specific applications. For example, a dual 500 gallon mobile bioreactor system, with a continuous flow capacity of 3 gpm, is available for emergency response to surface and/or underground spills. CytoCulture's bioremediation systems can also be fabricated as closed systems (carbon filter vented) to handle flammable solvents and volatile fuels. Electrical components are avoided for safety and compatibility with refinery operations. The control systems are designed to assure safety, reliability and low maintenance. These bioreactors are easily maintained by trained staff on a weekly basis.

Past Projects - Groundwater

CytoCulture's longest ongoing project involved the bioremediation of hydrocarbon contaminated soil and groundwater in Emeryville, CA. This site, now a shopping center, was formerly a truck terminal with serious hydrocarbon contamination from surface spills, service activities and leaking underground fuel/waste oil tanks. Phase one of the project was designed to decontaminate groundwater. Upon project initiation, 4,000 gallons per day of heavily contaminated groundwater (+ floating oil) were processed through CytoCulture's dual bioreactor system. The hydraulic retention time of the bioreactors was regulated to allow complete degradation of contamination before discharge (typically 8-12 hours). The presence of free product meant that the influent had saturated levels of dissolved-phase hydrocarbons which were consistently reduced to non-detectable levels (less than 0.5 ppm TPH) in the effluent. Aromatic components (BTXE) were reduced from concentrations as high as 440 ppb of benzene to non-detectable (less than 1 ppb).

The project was halted when the original trucking company went bankrupt, but the county and regional water quality control board may force a restart of the operation. In the second phase, clean treated groundwater would be infiltrated into contaminated soil under pavement and buildings on the site. Infiltration up-field of the contaminated areas should augment the in-situ biodegradation of adsorbed hydrocarbon in the soil down-field. This project was performed effectively with minimal impact on appearance and with no effect on operations at the shopping center. A similar project operated for six months recycling groundwater at 10 gpm for irrigation of landscaping at Santa Clara University. Over 2.2 million gallons of gasoline-contaminated groundwater were cleaned to drinking water standards at less than 4 cents/gallon.

In Santa Rosa, CytoCulture installed the first augmented in situ groundwater bioremediation system to be ever permitted in the district (from Santa Rosa to Oregon) controlled by the North Coast Regional Water Quality Control Board. The 5 gpm system treated gasoline-contaminated groundwater in an above-ground bioreactor system. The treated water, cleaned to drinking water standards, was reinfiltrated back to the aquifer via infiltration wells in the former fuel tank pit. The oxygenated infiltrate carried nutrients and hydrocarbon-degrading aerobic bacteria generated in the bioreactors. In the first five months, the gasoline hydrocarbon dropped from 47 ppm (with evidence of free product) to less than 3 ppm in the most contaminated zone. More striking was the 1,000 fold increase in density of bacteria detected in the extracted groundwater just down-gradient from the gasoline plume. In situ counts of hydrocarbon-degrading bacteria were stimulated from a background level of 1,000 colony forming units per milliliter (cfu/ml) to over 1 million cfu/ml over a period of about 2 months. These in situ bacteria were shown in the laboratory to grow well on petroleum hydrocarbons as their sole source of carbon. The industrial site received a Closure Letter from the North Coast RWQCB after 8 months of continuous groundwater bioremediation at 5 gpm.

Two similar in situ groundwater bioremediation projects were completed in 1996 at a new shopping center in Redwood City for Safeway, Inc. These sites operated at 5 gpm and 7 gpm over a period of 6 to 15 months, respectively. Dissolved phase petroleum hydrocarbons in the groundwater were reduced to less than 1 ppm. Both sites were closed by the local Department of Health Services (San Mateo County). The second site was treated for residual levels of chlorinated solvents using a groundwater air stripping system.

Past Projects - Soil

The CytoCulture clean-up approach favors the simultaneous treatment of both contaminated groundwater and soil, when appropriate, using an integrated bioremediation program. The in situ bioremediation projects described above are designed to maximize the degradation of hydrocarbons adsorbed to soil particles in the saturated zone. Microbial degradation of solid phase hydrocarbons is restricted to zones in direct contact with the infiltrated nutrients and bacteria. Careful hydraulic control of the groundwater treatment can optimize this contact, and may even extend the treatment into vadose zone areas by a combination of subsurface infiltration galleries and controlled mounding of the infiltrate. However, subsurface biodegradation rates are generally expected to be much slower than those routinely achieved with excavated soil treatment.

In ex situ soil applications where rapid clean-up is required, a leach field approach can be employed for the continual recirculation of a treatment solution containing high density cultures of petroleum-selective aerobic bacteria, biodegradable emulsifiers and nutrients. This "soil washing" process accelerates the desorption of heavier petroleum fractions into the aqueous phase and facilitates biodegradation of solubilized hydrocarbon. The leach field system may also be used to extract toxic metals with a combination of dilute organic acids and chelating agents. In Oakland, CA, CytoCulture was contracted to provide bioreactors and technical field service for the bioremediation of excavated diesel contaminated soil using the soil washing approach. In less than 10 weeks of operation, the average composite TPH decreased from 2,100 ppm to 85 ppm. Site closure was approved with residual hydrocarbon levels of less than 10 ppm (3 months).

In ex situ soil applications where space is limited or where air emissions are serious concern (urban or South Coast Districts), CytoCulture employs a vacuum heap approach. Vacuum heap bioremediation is a process in which air is drawn through a pile of excavated soil to oxygenate bacteria inoculated into the soil pile. Continual introduction of oxygen, nutrients and water accelerates the biodegradation of the heavier fractions of petroleum contamination with minimal air stripping. The entire vacuum heap is covered with plastic to retain moisture, increase passive solar heating and minimize the release of volatile organics.

In 1989, CytoCulture was contracted by the City of Oxnard to construct a vacuum heap bioremediation system to decontaminate 2,400 cubic yards of soil at a pipeline spill site. As prime contractor, CytoCulture designed and built the soil treatment system to degrade diesel and crude oil. In the first month of treatment, the average TPH values were reduced from 6,700 ppm to 500 ppm. Site closure was approved after three months of operation, with average residual contamination levels of <2 ppm.

Two similar vacuum heap projects have been approved by San Mateo County and the SF Bay Regional Water Quality Control Board for installation at the shopping center site in Redwood City where CytoCulture will have two in situ groundwater systems operating.

When space is available and air emissions are minimal (heavy petroleum fractions only), CytoCulture has employed an augmented land farming approach, similar to conventional soil treatments. However, the CytoCulture approach combines high density bacterial cultures, surfactant and both solid-phase and water soluble nutrients to optimize the rapid biodegradation of hydrocarbon contaminants.

Oxygenation is provided by frequent tilling and/or turning of the soil. Laboratory surveillance of the microbial populations confirm that both indigenous and exogenous strains of hydrocarbon-degraders flourish under these treatment conditions.

CytoCulture completed two augmented land farming projects for Chevron USA Production Company in Casmalia, CA. The first project, a 500 cubic yard pilot study that led to subsequent scale-up, was a comparative study of five different combinations of amendments and augmentation, employed with conventional tilling and irrigation procedures. CytoCulture provided the study design parameters as well as all microbiological analysis, data review, and interpretation. Included in the study was CytoCulture's own proprietary BioSolvent utilized as an adjuvant to facilitate the desorption of adsorbed phase hydrocarbons from the clays and fractured sisquac rock. The successful results of the pilot study led to the scale-up of the most cost and time effective measures for the bioremediation of an additional 1500 cubic yards. The estimated half life for the degradation of the petroleum hydrocarbons (TPH levels), given the results of the Pilot Study was 6 weeks.

The 1500 cubic yard scale-up soil bioremediation study confirmed predictions made in the initial pilot study. The cost-efficient approach, using conventional, but carefully controlled land-farming techniques allowed the biodegradation of petroleum contaminants with a half life of approximately five weeks on a large scale. Initial TPH concentrations (K/D Diluent and crude oil) in the mixed soil bed at the beginning of the study ranged from 1,200 to 1,800 mg/kg, with a starting average of 1,400 mg/kg. Within the first four weeks, the TPH concentrations had been reduced to the range of 680 to 1,100 mg/kg, with an average TPH of 830 mg/kg. After eight weeks, the soil bed TPH concentrations had been further reduced to the range of 390-660 mg/kg, with an average TPH of 508 mg/kg.

A similar land farming project in Oxnard involving 2,400 cubic yards of crude oil-contaminated clay soil was closed in March of 1991 after only six months of biotreatment through the winter (diesel to < 100 ppm, BTXE to N.D. and crude oil heavy fractions to less than 1,000 ppm). Land farming is usually the least expensive bioremediation option for heavily contaminated soil when soil conditions, volatile emissions and space requirements are acceptable.

Industrial Biotreatment

CytoCulture also has limited experience in the biological treatment of industrial hazardous waste streams. At the Naval Air Station in Alameda, CA, CytoCulture provided technical assistance in treating waste water from paint stripping operations. Using laboratory selected bacteria, phenol and methylene chloride concentrations have been reduced from 2,500 ppm and 1,000 ppm, respectively, to less than 10 ppm for discharge.

New industrial biotreatment projects were modeled in our laboratory for petroleum refinery waste water operations. Starting with bench scale studies to develop sole carbon source enrichment isolates, CytoCulture designed pilot and full scale fixed-film bioreactors for on-line pretreatment of phenol at a local refinery (phenol in excess of 4,000 ppm is reduced to 10 ppm).

The laboratory studies culminated with the successful operation of a continuous-flow, fixed film 100 gallon bioreactor system treating concentrated phenol-contaminated waste water.

Partial List of CytoCulture Bioremediation / Industrial Clients