Ronald C. Sims

Production and harvesting of microalgae for wastewater treatment, biofuels, and bioproducts

The integration of microalgae-based biofuel and bioproducts production with wastewater treatment has major advantages for both industries. However, major challenges to the implementation of an integrated system include the large-scale production of algae and the harvesting of microalgae in a way that allows for downstream processing to produce biofuels and other bioproducts of value. Although the majority of algal production systems use suspended cultures in either open ponds or closed reactors, the use of attached cultures may offer several advantages. With regard to harvesting methods, better understanding and control of autoflocculation and bioflocculation could improve performance and reduce chemical addition requirements for conventional mechanical methods that include centrifugation, tangential filtration, gravity sedimentation, and dissolved air flotation. There are many approaches currently used by companies and industries using clean water at laboratory, bench, and pilot scale; however, large-scale systems for controlled algae production and/or harvesting for wastewater treatment and subsequent processing for bioproducts are lacking. Further investigation and development of large-scale production and harvesting methods for biofuels and bioproducts are necessary, particularly with less studied but promising approaches such as those involving attached algal biofilm cultures.

Evaluation of the Use of Prairie Grasses for Stimulating Polycyclic Aromatic Hydrocarbon Treatment in Soil

Abstract A research project was conducted to evaluate enhanced treatment of toxic organic chemicals in soil using deep rooted grasses. Eight types of prairie grasses were evaluated in the treatment of four polycyclic aromatic hydrocarbons (PAHs) in a sandy loam soil. The extent of PAH disappearance in vegetated soil was significantly greater than in unvegetated soil.

Fate of polynuclear aromatic compounds (PNAs) in soil-plant systems

Polycyclic aromatic hydrocarbons (PAH) consist of three or more fused benzene rings in linear, angular, or cluster arrangements. Substitution of carbon in the benzene ring with nitrogen, sulfur, oxygen, or other elements creates heterocyclic aromatic compounds (Blumer 1976). Excluding diphenyl types there are some 70 possible isomers of 4-6 fused rings. Additionally these isomers may be substituted by a variety of substituents (Erskine and Whitehead 1975). The aromatic hydrocarbons and heterocycles, unsubstituted and substituted, are referred to alternatively as polynuclear aromatics (PNAs), polycyclic aromatic compounds (PCAs), and polycyclic organic matter (POM) (NAS 1972, U.S. EPA 1975 b).

Rotating algal biofilm reactor and spool harvester for wastewater treatment with biofuels by‐products

Maximizing algae production in a wastewater treatment process can aid in the reduction of soluble nitrogen and phosphorus concentrations in the wastewater. If harvested, the algae‐based biomass offers the added benefit as feedstock for the production of biofuels and bioproducts. However, difficulties in harvesting, concentrating, and dewatering the algae‐based biomass have limited the development of an economically feasible treatment and production process. When algae‐based biomass is grown as a surface attached biofilm as opposed to a suspended culture, the biomass is naturally concentrated and more easily harvested. This can lead to less expensive removal of the biomass from wastewater, and less expensive downstream processing in the production of biofuels and bioproducts. In this study, a novel rotating algal biofilm reactor (RABR) was designed, built, and tested at bench (8 L), medium (535 L), and pilot (8,000 L) scales. The RABR was designed to operate in the photoautotrophic conditions of open tertiary wastewater treatment, producing mixed culture biofilms made up of algae and bacteria. Growth substrata were evaluated for attachment and biofilm formation, and an effective substratum was discovered. The RABR achieved effective nutrient reduction, with average removal rates of 2.1 and 14.1 g m−2 day−1 for total dissolved phosphorus and total dissolved nitrogen, respectively. Biomass production ranged from 5.5 g m−2 day−1 at bench scale to as high as 31 g m−2 day−1 at pilot scale. An efficient spool harvesting technique was also developed at bench and medium scales to obtain a concentrated product (12–16% solids) suitable for further processing in the production of biofuels and bioproducts. Biotechnol. Bioeng. 2012; 109:1674–1684.

Acetone, butanol, and ethanol production from wastewater algae.

Acetone, butanol, and ethanol (ABE) fermentation by Clostridium saccharoperbutylacetonicum N1-4 using wastewater algae biomass as a carbon source was demonstrated. Algae from the Logan City Wastewater Lagoon system grow naturally at high rates providing an abundant source of renewable algal biomass. Batch fermentations were performed with 10% algae as feedstock. Fermentation of acid/base pretreated algae produced 2.74 g/L of total ABE, as compared with 7.27 g/L from pretreated algae supplemented with 1% glucose. Additionally, 9.74 g/L of total ABE was produced when xylanase and cellulase enzymes were supplemented to the pretreated algae media. The 1% glucose supplement increased total ABE production approximately 160%, while supplementing with enzymes resulted in a 250% increase in total ABE production when compared to production from pretreated algae with no supplementation of extraneous sugar and enzymes. Additionally, supplementation of enzymes produced the highest total ABE production yield of 0.311 g/g and volumetric productivity of 0.102 g/Lh. The use of non-pretreated algae produced 0.73 g/L of total ABE. The ability to engineer novel methods to produce these high value products from an abundant and renewable feedstock such as algae could have significant implications in stimulating domestic energy economies.

Isolation and Characterization of Polycyclic Aromatic Hydrocarbon–Degrading Mycobacterium Isolates from Soil

Bioremediation of soils contaminated with wood preservatives containing polycyclic aromatic hydrocarbons (PAHs) is desired because of their toxic, mutagenic, and carcinogenic properties. Creosote wood preservative–contaminated soils at the Champion International Superfund Site in Libby, Montana currently undergo bioremediation in a prepared-bed land treatment unit (LTU) process. Microbes isolated from these LTU soils rapidly mineralized the 14C-labeled PAH pyrene in the LTU soil. Gram staining, electron microscopy, and 16S rDNA-sequencing revealed that three of these bacteria, JLS, KMS, and MCS, were Mycobacterium strains. The phylogeny of the 16S rDNA showed that they were distinct from other Mycobacterium isolates with PAH-degrading activities. Catalase and superoxide dismutase (SOD) isozyme profiles confirmed that each isolate was distinct from each other and from the PAH-degrading mycobacterium, Mycobacterium vanbaalenii sp. nov, isolated from a petroleum-contaminated soil. We find that dioxygenase genes nidA and nidB are present in each of the Libby Mycobacterium isolates and are adjacent to each other in the sequence nidB-nidA, an order that is unique to the PAH-degrading mycobacteria.

Biodiesel from mixed culture algae via a wet lipid extraction procedure

Microalgae are a source of renewable oil for liquid fuels. However, costs for dewatering/drying, extraction, and processing have limited commercial scale production of biodiesel from algal biomass. A wet lipid extraction procedure was developed that was capable of extracting 79% of transesterifiable lipids from wet algal biomass (84% moisture) via acid and base hydrolysis (90 °C and ambient pressures), and 76% of those extracted lipids were isolated, by further processing, and converted to FAMEs. Furthermore, the procedure was capable of removing chlorophyll contamination of the algal lipid extract through precipitation. In addition, the procedure generated side streams that serve as feedstocks for microbial conversion to additional bioproducts. The capability of the procedure to extract lipids from wet algal biomass, to reduce/remove chlorophyll contamination, to potentially reduce organic solvent demand, and to generate feedstocks for high-value bioproducts presents opportunities to reduce costs of scaling up algal lipid extraction for biodiesel production.

Soil Remediation Techniques at Uncontrolled Hazardous Waste Sites

The objective of this critical review is to address soil remediation techniques at uncontrolled hazardous waste sites with regard to the following areas: 1) important regulatory and technical issues and information needs concerning soil remediation at uncontrolled hazardous waste sites; 2) approaches for selection of remediation techniques; and 3) the current state of knowledge regarding soil remediation techniques, including applications and limitations. The areas identified above are addressed with regard to current information, selected milestone publications, and specific applications of technologies to provide a synthesis of the topic. The information concerning current issues, approaches, and soil remediation techniques presented was critically reviewed in order to: 1) identify deficiencies in current approaches; 2) develop a conceptual framework for remediation; and 3) recommend improved approaches for selection of remediation technologies.

Evidence for cooxidation of polynuclear aromatic hydrocarbons in soil

Abstract The effect of constituent matrix on the degradation of hydrocarbons was characterized and evaluated within the context of cooxidation. Current information concerning the cooxidation process applied to hydrocarbons was evaluated and results were used to define a laboratory approach for studying the effects of constituent matrix on degradation rates of 13 polynuclear aromatic hydrocarbons (PAHs) in soil. Four matrices were studied: (1) single constituents applied and incubated singly; (2) a synthetic mixture of PAHs applied and incubated together; (3) a mixture of oil refinery wastes; (4) and a creosote wood preserving waste. Initial soil concentrations of constituents were similar for each matrix evaluated. One soil was used, a Kidman fine sandy loam (Haplustoll, Utah). Incubation conditions and extraction and analysis methods were similar among the studies. Four and 5-ring PAHs were found to disappear more rapidly from soils amended with complex wastes, while degradation rates for 3-ring compounds in all matrices were similar. These results can be interpreted in the context of cooxidation and suggest a potential tool for bioremediation of PAH contaminated soils and the simultaneous protection of groundwater resources through reduction or mitigation of groundwater contamination due to vadose zone-associated PAHs.

Study of Biochemical Pathways and Enzymes Involved in Pyrene Degradation by Mycobacterium sp. Strain KMS

ABSTRACT Pyrene degradation is known in bacteria. In this study, Mycobacterium sp. strain KMS was used to study the metabolites produced during, and enzymes involved in, pyrene degradation. Several key metabolites, including pyrene-4,5-dione, cis-4,5-pyrene-dihydrodiol, phenanthrene-4,5-dicarboxylic acid, and 4-phenanthroic acid, were identified during pyrene degradation. Pyrene-4,5-dione, which accumulates as an end product in some gram-negative bacterial cultures, was further utilized and degraded by Mycobacterium sp. strain KMS. Enzymes involved in pyrene degradation by Mycobacterium sp. strain KMS were studied, using 2-D gel electrophoresis. The first protein in the catabolic pathway, aromatic-ring-hydroxylating dioxygenase, which oxidizes pyrene to cis-4,5-pyrene-dihydrodiol, was induced with the addition of pyrene and pyrene-4,5-dione to the cultures. The subcomponents of dioxygenase, including the alpha and beta subunits, 4Fe-4S ferredoxin, and the Rieske (2Fe-2S) region, were all induced. Other proteins responsible for further pyrene degradation, such as dihydrodiol dehydrogenase, oxidoreductase, and epoxide hydrolase, were also found to be significantly induced by the presence of pyrene and pyrene-4,5-dione. Several nonpathway-related proteins, including sterol-binding protein and cytochrome P450, were induced. A pyrene degradation pathway for Mycobacterium sp. strain KMS was proposed and confirmed by proteomic study by identifying almost all the enzymes required during the initial steps of pyrene degradation.