Craig R. Woolard

Treatment of hypersaline wastewater in the sequencing batch reactor

Abstract Hypersaline wastes are generated during industrial activities that include chemical manufacturing, oil and gas production and waste minimization practices. These wastes which contain organic compounds and high concentrations of salt (>3.5%), are difficult to treat using conventional microorganisms typically found in wastewater facilities. Biological treatment to remove organics without dilution will require the use of halophilic organisms which have special adaptations for survival at high salinities. In this paper, studies were conducted with a moderate halophile isolated from the Great Salt Lake, Utah, U.S.A. The organism was able to degrade phenol in a simulated oil field produced water containing 15% salt if iron, nitrogen and phosphorus were added to the medium. This organism was used to develop a halophilic sludge in a Sequencing Batch Reactor (SBR) operated at 15% salt during a 7 month study period. An average phenol removal of over 99.5% was achieved with this reactor and specific substrate removal rates were similar to those reported for more conventional treatment cultures.

Natural organic matter and DBP formation potential in Alaskan water supplies

Disinfection by-products (DBP) are formed when natural organic matter (NOM) in water reacts with a disinfectant, usually chlorine. DBPs are a health risk element and regulated under the Safe Drinking Water Act. A study was conducted to evaluate the characteristics of NOM that contribute to DBPs in 17 different drinking water systems in Alaska. In order to determine the nature of the organic matter contributing to DBPs, DBP formation potential was compared with standard water quality parameters such as UV-254, color and dissolved organic carbon (DOC), as well as pyrolysis-gas chromatography/mass spectrometry (GC/MS). Results showed strong correlations between UV-254 and DBP formation potential for all waters studied. DOC, on the other hand, was less strongly correlated to DBP formation potential. Unlike previous studies, the total trihalomethane and haloacetic acid formation potentials were equal on a mass concentration basis for the waters studied. Pyrolysis-GC/MS indicated that NOM contributing to DBPs were primarily phenolic compounds. This finding was consistent with previous studies; however, unlike other studies, no correlation was found between aliphatic compounds in the raw waters and DBP formation potential.

Enhancement and inhibition of soil petroleum biodegradation through the use of fertilizer nitrogen: An approach to determining optimum levels

Laboratory studies were conducted to evaluate the relationship between soil water content and microbial response to soil nitrogen (N) in petroleum‐contaminated soils. Various levels of N were added to a sand, a sandy loam, and a silt loam. Measurements of the extent of biodegradation in each soil (petroleum loss or CO2 production) indicated that biodegradation was related to soil N expressed as a function of soil water (mg N/kg soil H2O or mg N/I) better than N expressed as a function of soil dry matter (mg N/kg soil). A loamy sand was treated with four levels of N (0, 250, 500, 750 mg N/kg soil) and incubated at three water contents (5.0, 7.5, and 10.0% on a dry soil weight basis). Soil water potential and O2 consumption were best related to N expressed on the basis of soil water. It is concluded that expressing N in units of mg N/kg soil H2O (easily obtained by dividing [mg N/kg dry soil] by [soil moisture content]) can be used to determine fertilization rates for bioremediation processes. On this basis...

Nutrient and temperature interactions in bioremediation of cryic soils

Low temperatures and lack of available nutrients often limit the rate of microbial petroleum hydrocarbon degradation in contaminated cryic soils. Proper management of both these parameters may increase microbial respiration in such soils. Interactions between nutrient level and temperature could impact management decisions for both factors, but these interactions have not previously been adequately described. Petroleum-contaminated soils from two Alaskan sites were studied in separate laboratory experiments. Nutrients and incubation temperatures were independently varied so interactions between the two could be studied. Soil from a gravel pad near Barrow, AK responded positively to temperatures increasing from 5°C to 20°C, and to addition of 50 or 100 mg/kg of supplemental nitrogen. Soil from Ft. Wainwright, AK responded positively as temperatures were increased from 1°C to 21°C, but microbial respiration decreased when temperatures were raised to 41°C. Microbial activity increased when 100 or 200 mg/kg of supplemental nitrogen was applied. In both soils, there were positive interactions between soil temperature response and addition of nitrogen fertilizer. Microbial response to soil warming was accentuated by proper nitrogen management, and response to fertilizer application was greatest when soil was warmed.

Nutrient amendments for contaminated peri-glacial soils: use of cod bone meal as a controlled release nutrient source

The lack of available nutrients, particularly nitrogen, often limits the rate of microbial petroleum hydrocarbon degradation in contaminated cold region soils. Microbial activity in many peri-glacial soils responds to addition of nitrogen, although excess levels can inhibit biodegradation by decreasing soil water potentials. Aqueous soluble inorganic fertilizer quickly partitions into soil water, increasing the salt concentration, and imposing an osmotic potential. Strategies that can be used to avoid microbial inhibition include the use of controlled release fertilizers. We studied the use of an organic fertilizer, cod bone meal, as a nutrient source for bioremediation. Nitrogen mineralization from cod bone meal was greater at 20 °C (first-order reaction rate constant k=0.0206 d -1 ) than at 10 °C (k=0.0154 d -1 ) and greater at pH 6.5 and 7.5 (k=0.0208 and 0.0189 d -1 , respectively) than at pH 5.5 (k=0.0143 d -1 ). Net O 2 consumption from diesel fuel degradation in a contaminated soil was greatly increased by addition of nitrogen and phosphorus in the form of diammonium phosphate (DAP) or cod bone meal relative to unfertilized soil. Cod bone meal fertilized soils had greater net O 2 consumption than DAP fertilized soils. However, residual soil hydrocarbon analyses indicated no difference in petroleum loss between the two nutrient sources.

The use of solid peroxides to stimulate growth of aerobic microbes in tundra

Solid peroxides and peroxyhydrates degrade into a basic salt, water, and molecular oxygen when in contact with biologically active soils. Column reactors were used to quantify the extent to which three solid peroxides would stimulate growth of aerobic, heterotrophic bacteria and fungi in contaminated tundra soil. Soils in contact with a peroxide compound were incubated in column reactors at field moisture conditions at either 12 or 25°C with no mixing. After 1200-h incubations, localized concentrations of bacteria and fungi were at least 2 orders of magnitude greater in soil amended with sodium carbonate peroxyhydrate than in soil containing either calcium peroxide or magnesium peroxide. Only in soil containing sodium carbonate peroxyhydrate did microbes grow to an appreciably higher concentration than in control soil, which contained no peroxide. Stimulation of both bacterial and fungal growth occurred primarily at distances of less than 5 cm from the peroxide, suggesting that under static moisture conditions, only localized microbial growth can be expected in acidic tundra soils.

Laboratory model of a petroleum migration barrier in arctic alaska

Childs Pad is a gravel construction pad that was contaminated with petroleum during oil-field service operations in Deadhorse, AK. As part of a remedial action plan, a buffer strip of uncontaminated sandy gravel was placed along certain sections of the pad boundary. A peroxygen formulation manufactured by Regenesis Copyright, sold as Oxygen Release Compound (ORC(R)), was placed in the buffer strips. The ORC was intended to supply oxygen to aerobic microorganisms capable of degrading petroleum. Tests were conducted in a 1/2 scale laboratory cell to determine the oxygen release characteristics of the ORC when subjected to expected subsurface flow rates of up to 0. 02 l/s (6.9 m/day). In laboratory tests, a zone of enhanced oxygen concentration was formed down-gradient from the ORC socks. Only during periods when the flow rate was less than 0.01-0.015 l/s (3. 5-5.2 m/day) was ORC-oxygen observed at monitoring points up-gradient or directly cross-gradient of the ORC. Conclusions from the laboratory study were that ORC may provide an aerobic zone in the Childs Pad barrier as far as 1 m directly down-gradient of the sock during periods of high flows (6.9 m/day). Copyright 1999 Elsevier Science B.V.

Analytical methods for petroleum in cold region soils

Introduction In order to demonstrate the effectiveness of a bioremediation project, one must have an accurate measure of the contaminants, both at the start of the project and throughout the treatment process. The measurement of the contaminants throughout the process is important to demonstrate that the treatment is successful and to identify advances or set-backs quickly and effectively. Proving the disappearance of hydrocarbons is important to the success of a bioremediation project. An accurate measurement of hydrocarbons and their biodegradation products is needed to confirm that petroleum was actually consumed by bacteria (discussed in Chapter 7, Section 7.3). One method of confirming biodegradation of petroleum is the coupled measurement of biodegradation rates by proxy methods and the disappearance of the contaminant. Biodegradation rates do not, in and of themselves, prove the decomposition of contaminants. Measurement of biodegradation rates, however, can be an easy way to demonstrate that the potential exists for contaminant removal. While measures of biodegradation rates are often used to estimate time to closure for a site, or proof of technology, biodegradation rates can be unreliable. Common measures of aerobic biodegradation are loss of contaminants, oxygen (O 2 ) consumption, and carbon dioxide (CO 2 ) evolution. Unfortunately, the CO 2 can result from non-biological sources (see Chapter 7, Section 7.2.2.2 for additional discussion). Particularly in low pH groundwater, pH adjustment made during bioremediation could result in CO 2 off-gassing from groundwater. Oxygen depletion in the subsurface is also not proof of biodegradation.

Bioremediation of Petroleum Hydrocarbons in Cold Regions: Analytical methods for petroleum in cold region soils

Introduction In order to demonstrate the effectiveness of a bioremediation project, one must have an accurate measure of the contaminants, both at the start of the project and throughout the treatment process. The measurement of the contaminants throughout the process is important to demonstrate that the treatment is successful and to identify advances or set-backs quickly and effectively. Proving the disappearance of hydrocarbons is important to the success of a bioremediation project. An accurate measurement of hydrocarbons and their biodegradation products is needed to confirm that petroleum was actually consumed by bacteria (discussed in Chapter 7, Section 7.3). One method of confirming biodegradation of petroleum is the coupled measurement of biodegradation rates by proxy methods and the disappearance of the contaminant. Biodegradation rates do not, in and of themselves, prove the decomposition of contaminants. Measurement of biodegradation rates, however, can be an easy way to demonstrate that the potential exists for contaminant removal. While measures of biodegradation rates are often used to estimate time to closure for a site, or proof of technology, biodegradation rates can be unreliable. Common measures of aerobic biodegradation are loss of contaminants, oxygen (O 2 ) consumption, and carbon dioxide (CO 2 ) evolution. Unfortunately, the CO 2 can result from non-biological sources (see Chapter 7, Section 7.2.2.2 for additional discussion). Particularly in low pH groundwater, pH adjustment made during bioremediation could result in CO 2 off-gassing from groundwater. Oxygen depletion in the subsurface is also not proof of biodegradation.