Sustainable development requires the development and promotion of environmental management and a constant search for green technologies to treat a wide range of aquatic and terrestrial habitats contaminated by increasing anthropogenic activities. Bioremediation is an increasingly popular alternative to conventional methods for treating waste compounds and media with the possibility to degrade contaminants using natural microbial activity mediated by different consortia of microbial strains. Many studies about bioremediation have been reported and the scientific literature has revealed the progressive emergence of various bioremediation techniques. In this review, we discuss the various in situ and ex situ bioremediation techniques and elaborate on the anaerobic digestion technology, phytoremediation, hyperaccumulation, composting and biosorption for their effectiveness in the biotreatment, stabilization and eventually overall remediation of contaminated strata and environments. The review ends with a note on the recent advances genetic engineering and nanotechnology have had in improving bioremediation. Case studies have also been extensively revisited to support the discussions on biosorption of heavy metals, gene probes used in molecular diagnostics, bioremediation studies of contaminants in vadose soils, bioremediation of oil contaminated soils, bioremediation of contaminants from mining sites, air sparging, slurry phase bioremediation, phytoremediation studies for pollutants and heavy metal hyperaccumulators, and vermicomposting.

A comprehensive overview of elements in bioremediation

This protocol is designed to evaluate the fate in ground water of chlorinated aliphatic hydrocarbons and/or fuel hydrocarbons. The data collected under this protocol can be used to compare the relative effectiveness of other remedial options and natural attenuation. This protocol should be used to evaluate whether monitored natural attenuation by itself or in conjunction with other remedial technologies is sufficient to achieve site-specific remedial objectives. Understanding the contaminant flow field in the subsurface is essential for a technically justified evaluation of a monitored natural attenuation remedial option; therefore, use of this protocol is not appropriate for evaluating monitored natural attenuation at sites where the contaminant flow field cannot be determined with an acceptable degree of certainty (e.g., complex fractured bedrock, karst aquifers).

/pdf/technical-protocol-for-evaluating-natural-attenuation-of-catf5ob7ug.pdf

Technical protocol for evaluating natural attenuation of chlorinated solvents in ground water

AR 840-10 Installation Confinement Facilities. Uniform Treatment of Military Prisoners. Administration. Duty Rosters. Army Bands. Dictionary of United States Army Terms. Salutes, Honors, and Visits of Courtesy. Discharge-Unfitness and Unsuitability. Description and Use of Flags, Guidons, Tabards, and Automobile Plates. The Military Policeman. Confinement and Correctional Treatment of Military Prisoners. Drill and Ceremonies. Uniform Code of Military Justice; Articles— Apprehension. Imposition of Restraint. Reports and Receiving of Prisoners. Releasing Prisoner Without Proper Authority. Unlawful Detention of Another. Improper Use of Countersign. Misbehavior of Sentinel on Lookout. FM 19-5 FM 19-60

Appendix A: References

The intent of this document is to present a technical protocol for data collection and analysis in support of intrinsic remediation with long term monitoring (LTM) for restoration of groundwater contaminated with fuel hydrocarbons. Specifically, this protocol is designed to evaluate the fate in groundwater of fuel hydrocarbons that have regulatory standards. Intrinsic remediation is an innovative remedial approach that relies on natural attenuation to remediate contaminants in the subsurface. In many cases, the use of this protocol will allow the proponent of intrinsic remediation to show that natural degradation processes will reduce the concentrations of these contaminants to below regulatory standards before potential receptor exposure pathways are completed. The evaluation should include consideration of existing exposure pathways, as well as exposure pathways arising from potential future use of the groundwater.

Technical Protocol for Implementing Intrinsic Remediation with Long-Term Monitoring for Natural Attenuation of Fuel Contamination Dissolved in Groundwater. Volume II.

The infiltration of dense non-aqueous-phase liquids (DNAPLs) into the saturated subsurface typically produces a highly contaminated zone that serves as a long-term source of dissolved-phase groundwater contamination. Applications of aggressive physical-chemical technologies to such source zones may remove > 90% of the contaminant mass under favorable conditions. The remaining contaminant mass, however, can create a rebounding of aqueous-phase concentrations within the treated zone. Stimulation of microbial reductive dechlorination within the source zone after aggressive mass removal has recently been proposed as a promising staged-treatment remediation technology for transforming the remaining contaminant mass. This article reviews available laboratory and field evidence that supports the development of a treatment strategy that combines aggressive source-zone removal technologies with subsequent promotion of sustained microbial reductive dechlorination. Physical-chemical source-zone treatment technologies compatible with posttreatment stimulation of microbial activity are identified, and studies examining the requirements and controls (i.e., limits) of reductive dechlorination of chlorinated ethenes are investigated. Illustrative calculations are presented to explore the potential effects of source-zone management alternatives. Results suggest that, for the favorable conditions assumed in these calculations (i.e., statistical homogeneity of aquifer properties, known source-zone DNAPL distribution, and successful bioenhancement in the source zone), source longevity may be reduced by as much as an order of magnitude when physical-chemical source-zone treatment is coupled with reductive dechlorination.

Coupling Aggressive Mass Removal with Microbial Reductive Dechlorination for Remediation of DNAPL Source Zones: A Review and Assessment

In situ air sparging (IAS) is becoming a widely used technology for remediating sites contaminated by volatile organic materials such as petroleum hydrocarbons. Published data indicate that the injection of air into subsurface water saturated areas coupled with soil vapor extraction (SVE) can increase removal rates in comparison to SVE alone for cases where hydrocarbons are distributed within the water saturated zone. However, the technology is still in its infancy and has not been subject to adequate research, nor have adequate monitoring methods been employed or even developed. Consequently, most IAS applications are designed, operated, and monitored based upon the experience of the individual practitioner.

The use of in situ air sparging poses risks not generally associated with most practiced remedial technologies: air injection can enhance the undesirable off-site migration of vapors and ground water contamination plumes. Migration of previously immobile liquid hydrocarbons can also be induced. Thus, there is an added incentive to fully understand this technology prior to application.

This overview of the current state of the practice of air sparging is a review of available published literature, consultation with practitioners, a range of unpublished data reports, as well as theoretical considerations. Potential strengths and weaknesses of the technology are discussed and recommendations for future investigations are given.

An Overview of In Situ Air Sparging

An in situ test method to measure the aerobic biodegradation rates of hydrocarbons in contaminated soil is presented. The test method provides an initial assessment of bioventing as a remediation technology for hydrocarbon-contaminated soil. The in situ respiration test consists of ventilating the contaminated soil of the unsaturated zone with air and periodically monitoring the depletion of oxygen (O2) and production of carbon dioxide (CO2) over time after the air is turned off. The test is simple to implement and generally takes about four to five days to complete. The test was applied at eight hydrocarbon-contaminated sites of different geological and climatic conditions. These sites were contaminated with petroleum products or petroleum fuels, except for two sites where the contaminants were primarily polycyclic aromatic hydrocarbons. Oxygen utilization rates for the eight sites ranged from 0.02 to 0.99 percent O2/hour. Estimated biodegradation rates ranged from 0.4 to 19 mg/kg of soil/day. These rates were similar to the biodegradation rates obtained from field and pilot studies using mass balance methods. Estimated biodegradation rates based on O2 utilization were generally more reliable (especially for alkaline soils) than rates based on CO2 production. CO2 produced from microbial respiration was probably converted to carbonate under alkaline conditions.

https://www.tandfonline.com/doi/pdf/10.1080/10473289.1992.10467077

A rapid in situ respiration test for measuring aerobic biodegradation rates of hydrocarbons in soil

Enhancing biodegradation of petroleum hydrocarbons through soil venting

: Air sparging generally involves the injection of air into an aquifer through vertical or horizontal wells. In situations where contaminant vapor recovery is necessary (e.g., as required by regulation, or in situations where vapor migration could cause adverse impacts), air sparging systems are coupled with soil vapor extraction (SVE) systems. Historically, practitioners have installed air sparging systems to: (1) treat immiscible contaminant source zones at or below the capillary fringe; (2) remediate dissolved contaminant plumes; and (3) provide barriers to prevent dissolved contaminant plume migration. Air sparging systems are also now being incorporated into novel aquifer bioremediation schemes for the delivery of other gases (e.g., oxygen, hydrogen, propane), and they have also been used as a means of improving air distribution for bioventing applications targeting near-capillary fringe soils. Some practitioners implement a variation of air sparging that they term biosparging. In practice, the term biosparging is frequently used to refer to air sparging systems when the intent is to operate without an SVE system. The helium air recovery tests discussed above can be used to quantify the efficiency of vapor capture during combined IAS and SVE operation, and can provide valuable insight to the areal distribution of IAS treatment zones. The ease and speed with which these tests can be conducted and interpreted makes them well suited for IAS pilot tests (even 1-day tests). The helium tests can also be conducted on full-scale systems already in operation to confirm that SVE system performance meets project goals. In addition, the tests can be easily repeated, which allows system parameters to be modified and the impact of those modifications to be quickly assessed. The three case histories presented here were chosen to represent the kinds of conclusion that can be drawn from the tests.

/pdf/air-sparging-design-paradigm-10rudywbtt.pdf

Air Sparging Design Paradigm

Bioventing is an extremely cost-effective method for treating soils contaminated with fuels (JP-4, diesel, gasoline, and heating oil) and non-chlorinated solvents. In April of this year, the Air Force Center for Environmental Excellence (AFCEE) launched a nation-wide bioventing initiative to test the effectiveness of this innovative process at 55 contaminated sites in nineteen states. Twenty systems have already been installed and tested. To ensure that systems were installed and tested consistently, AFCEE developed the comprehensive protocol document. With minimal site specific modifications, the protocol is also used as a regulatory test plan. The concept significantly reduces test plan preparation costs. The AFCEE document introduces the bioventing technology and describes the technical procedures used to set up a bioventing system for field evaluation. It also provides testing, equipment, measurements, and other relevant quantitative data.

Robert E. Hinchee

Papers

An Overview of In Situ Air Sparging

A rapid in situ respiration test for measuring aerobic biodegradation rates of hydrocarbons in soil

Enhancing biodegradation of petroleum hydrocarbons through soil venting

Air Sparging Design Paradigm

Test plan and technical protocol for a field treatability test for bioventing