Soil Pollution & Remediation at NW Pipe & Casing/Hall Process Site: PAHs, PCBs, VOCs - Pro, Papers of Agricultural engineering

Download Soil Pollution & Remediation at NW Pipe & Casing/Hall Process Site: PAHs, PCBs, VOCs - Pro and more Papers Agricultural engineering in PDF only on Docsity! Radio­Wave  Heating  Combine  Bioremediation  for  the  Organic  Pollution  Remediation  in  Northwest  Pipe  &  Hall Process Company Casing/ H S   ao Chen  oil and Water Department, UF, 10/21/08  Abstract  The soil in the superfund Northwest Pipe & Casing/Hall Process Company site has been heavily polluted by PAHs, PCBs and VOC. The remediation technology has been done in this site including: the removal and treatment or off-site disposal of highly contaminated surface and subsurface soils, the placement of a clean, re-vegetated soil cap. The remediation technology used in this site is quite useful here, but there are also some drawbacks of the main technology soil heating remediation, which transfers contaminants from one medium to another without destroying them. This paper further discuss another cost effective way about microwave heating combine bioremediation to remediate the heavily contaminant soil within this site. Besides, in consideration of the temperature of this site is relatively low, to use radio wave heating system to support micro degradation of pollutants is a real option for accelerated soil remediation . Introduction    Across the USA, there are many underground organic storage tanks and other facilities are no longer in use. Because many of there tanks and facilities have not been properly maintained, are rusted or leaking. Site contamination from these organic pollutions is an imminent concern for many communities seeking to develop abandoned properties for other uses. This is the case about former Northwest Pipe & Casing/Hall Process Company in Clackamas County, Oregon. A pipe coating business (Hall Process Company) operated at this site from 1956 to 1978. Northwest Pipe and Casing leased the Hall property between 1978 and 1985, during which Northwest Pipe and Casing operated the pipe coating facilities. Historical, on-site disposal and mishandling of wastes from pipe manufacturing and pipe coating operations are the primary sources of contamination at the site. Contaminants released at the site into the soil and groundwater were volatile organic compounds (VOCs), polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). EPA placed the Northwest Pipe site on the Superfund National Priorities List on October 14, 1992. Numerous areas of surface and subsurface soil on this site are contaminated with PAHs, PCBs and to a lesser extent with chlorinated volatile organic chemicals VOCs. The upper 3 feet of soil across this site has been moderately impacted by PAHs and PCBs. Average total HPAHs and total PCBs concentrations in subsurface samples from gridded test pits exceeded 25 mg/kg and 1.5 mg/kg respectively. As an example of the levels of individual HPAH compounds detected in soil, benzo(a)pyrene was detected in 18 of 21 surface soil samples at a mean concentration of 54.4 mg/kg and maximum concentration of 410 mg/kg. In subsurface soil, benzo(a)pyrene was detected in 80 out of 144 subsurface soil samples, at a mean concentration of 2.6 mg/kg and maximum concentration of 48 mg/kg. The remediation technology has been done in this site including: the removal and treatment or off-site disposal of highly contaminated surface and subsurface soils, the placement of a clean, re-vegetated soil cap. The implementation of institutional controls on this site that ensures the cap integrity is not impacted by future uses. The remediation technology used in this site is quite useful here, but there are also some drawbacks of the main technology soil heating remediation, which transfers contaminants from one medium to another without destroying them. This paper will further discuss another cost effective way about microwave heating combine bioremediation to remediate the heavily contaminant soil within this site. Biological methods seem to offer a respite as they treat and handle these pollutants in a natural context. Many biologically mediated pollutant removal techniques have been successfully employed in the field. Besides, in consideration of the temperature of this site is relatively low, this paper will further combine a radio wave heating system with the bioremediation system. Materials and Methods    Site Description The site covers approximately 53 acres of land, underlain by an upper water bearing This paper will further discuss another cost effective way about microwave heating combine bioremediation to remediate the heavily contaminant soil within this site. Biological methods seem to offer a respite as they treat and handle these pollutants in a natural context. Many biologically mediated pollutant removal techniques have been successfully employed in the field. Besides, in consideration of the temperature of this site is relatively low, this paper will further combine a radio wave heating system with the bioremediation system. Microorganism remediation Microorganisms play an important role in the degradation of PAHs and PCBs in terrestrial and aquatic ecosystems, and microbial degradation is the main process in natural decontamination. 1. PAH microorganism remediation Biodegradation of the two-ring PAH naphthalene in soil was first reported in the 1920’s and, since then, has been studied for the ability of bacteria to utilize the compound as the sole source of carbon and energy(Larsen, Karakashev et al.). Biological degradation of PAHs with up to five rings has been well studied. Lower molecular weight PAHs are degraded easily while high molecular weigh PAHs are difficult to degrade by normal enzymatic processes. Temperature plays an important role for the biodegradation of PAHs in soil.(Ferguson, Powell et al. 2008) Recent study in biological degradation of PAHs: Representative PAHs and PAH-degrading bacteria in soil Genera Representative PAHs Burkholderia Fluoranthene, pyrene, chrysene,coronene, benz(a)anthrancene, dibenz(a,h)anthrancene Cycloclasticus Naphthalene, benz(a)anthrancene, fluoranthene, pyrene, chrysene Flavobacterium Phenanthrene, benz(a)anthrancene, fluoranthene, pyrene, chrysene Mycobacterium Naphthalene, Phenanthrene, benz(a)anthrancene, fluoranthene, pyrene, chrysene Pseudomonas Naphthalene, fluoranthene, chrysene, Phenanthrene, benz(a)anthrancene, fluoranthene, pyrene Rhodococcus Naphthalene, fluoranthene, chrysene, Phenanthrene, fluoranthene, pyrene Sphingomonas Naphthalene, fluoranthene, 2-methylphenanthrene, 2,3-dimethylnaphthalene, fluorine, 3-chlorodibenzofuran, anthrancene, phenanthrene, pyrene, dibenzofruan Staphylococcus Dibenzofuran, dibenzo-p-dioxin, fluorene 2. PCBs microorganism remediation PCB degrading bacteria are ubiquitous and mostly aerobic in nature, Gram negative soil bacteria include Pseudomonas, Acinetobacter, etc; while Gram positive bacteria include Anthrobacter and Cornyebacterium species. These stains utilize PCBs as a sole source of carbon and energy and co-metabolize them into a number of components like chlorobenzoic acides via ring-dioxygenation and meta-cleavage. The degradation rate PCBs decrease with increase in chlorine substitution PCBs containing two chlorines in the ortho-position of single ring and each ring show a striking resistance to degradation. PCBs containing all chlorines on a single ring are generally degraded faster than those containing the same number on both rings. (Chávez, Gordillo et al. 2006) 3. Tretrachloroethene microorganism remediation The microbial reductive dechlorination process has gained increased acceptance as an effective remediation technology for Tretrachloroethene-impacted soil. Central to this process are bacteria that use chlorinated ethenes as terminal electron acceptors to fuel their energy metabolism. In chlororespiration, transfer of reducing equivalents derived from the oxidation of simple organic compounds (e.g., lactate, acetate) or hydrogen results in the reduction (i.e., dechlorination) of the chlorinated compound(s) and concomitant release of inorganic chloride.(Amos, Suchomel et al. 2008) Considerable effort has led to the identification and isolation of bacteria capable of respiratory reductive dechlorination(Amos, Christ et al. 2007). Most of the described isolates dechlorinate tetrachloroethene (PCE) to cis-1,2-dichloroethene (cis-DCE), and dechlorination past DCE appears to be limited to some members of the Dehalococcoides group(Löffler and Edwards 2006). Thermally-enhanced microbial soil remediation The remediation of contaminated soil can be significantly enhanced by increasing the temperature to desorb, mobilize, and evaporate pollutants, to initiate chemical reactions forming nonhazardous products or to support biodegradation. Besides, the temperature in this site is relatively low. Historical winter daytime temperatures are typically between 40 and 50 degrees Fahrenheit (EF), while nighttime temperatures range in the mid-to upper 30's. Summer daytime high temperatures typically range in the mid- to upper 70's, with nighttime summer lows in the 50's. Here this paper will further discuss the radio-wave heating combined microbial soil remediation. This technique has the advantage that a significant increase in the degradation rates can be achieved even with a relatively small energy input (heating up to about 35°C and stabilization of the temperature by compensating the heat loss). Additionally, under ideal conditions a complete conversion of the hydrocarbons to CO2 and H2O occurs, making a cleaning of the effluent flow unnecessary. A combination of low- and high-frequency electrical energy was successfully applied to homogeneously heat the capillary fringe, the boundary region of saturated and unsaturated zones. The energetic efficiency of the method was evaluated showing that an efficient transformation of RW energy to heat in the target volume can be achieved. By comparing biodegradation and soil respiration under conventional and electric (low-frequency resistive and dielectric RW) heating, the compatibility of the electric heating methods with bioremediation processes could be proven. Therefore, RW-supported microbial degradation of pollutants is a real option for accelerated soil remediation.(Roland, Buchenhorst et al. 2008) U. Roland etc.(Roland, Holzer et al. 2007) have conducted a long-term experiment about the combine of radio-wave heating and bioremediation technology for soil remediation. A heavily contaminated soil containing about 25 000 mg/kg mineral oil hydrocarbons, approx. 1 500 mg/kg BTEX aromatics and about 400 mg/kg polycyclic aromatic hydrocarbons was treated via a thermally-enhanced bioremediation. The moderate heating to a mean soil temperature of 37°C led to a marked increase of the soil respiration related to the degradation of organic pollutants. The advantages of radio-wave heating are most pronounced in those cases where the ambient temperature and the available carbon sources are not sufficient for a significant microbiological (auto-) heating. Conclusion  The soil in the superfund Northwest Pipe & Casing/Hall Process Company site has been