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Wastewater treatment for indirect potable reuse (IPR) is a possible approach to address water scarcity. In this study, a novel membrane bioreactor–membrane distillation (MBR-MD) system was evaluated to determine the environmental impacts of treatment compared to an existing IPR facility (“Baseline”). Physical and empirical models were used to obtain operational data for both systems and inform a life cycle inventory. Life cycle assessment (LCA) was used to compare the environmental impacts of each system. Results showed an average 53.7% reduction in environmental impacts for the MBR-MD system when waste heat is used to operate MD; however, without waste heat, the environmental impacts of MBR-MD are significantly higher, with average impacts ranging from 218% to 1400% greater than the Baseline, depending on the proportion of waste heat used. The results of this study demonstrate the effectiveness of the novel MBR-MD system for IPR and the reduced environmental impacts when waste heat is available to power MD.

This paper presents a continuous-flow cell screening device to isolate and separate microalgae cells (Chlamydomonas reinhardtii) based on lipid content using high frequency (50 MHz) dielectrophoresis. This device enables screening of microalgae due to the balance between lateral DEP forces relative to hydrodynamic forces. Positive DEP force along with amplitude-modulated electric field exerted on the cells flowing over the planar interdigitated electrodes, manipulated low-lipid cell trajectories in a zigzag pattern. Theoretical modelling confirmed cell trajectories during sorting. Separation quantification and sensitivity analysis were conducted with time-course experiments and collected samples were analysed by flow cytometry. Experimental testing with nitrogen starveddw15-1 (high-lipid, HL) and pgd1 mutant (low-lipid, LL) strains were carried out at different time periods, and clear separation of the two populations was achieved. Experimental results demonstrated that three populations were produced during nitrogen starvation: HL, LL and low-chlorophyll (LC) populations. Presence of the LC population can affect the binary separation performance. The continuous-flow micro-separator can separate 74% of the HL and 75% of the LL out of the starting sample using a 50 MHz, 30 voltages peak-to-peak AC electric field at Day 6 of the nitrogen starvation. The separation occurred between LL (low-lipid: 86.1% at Outlet # 1) and LC (88.8% at Outlet # 2) at Day 9 of the nitrogen starvation. This device can be used for onsite monitoring; therefore, it has the potential to reduce biofuel production costs

To assess the suitability of microalgal strains for biodiesel production the lipid content and composition, especially individual triacylglycerols (TAG) and free fatty acids (FFA) must be determined. In this study, the compositions and concentrations of TAG and FFA were analysed in four halophytic algal species, Dunaliella salina , D. tertiolecta , D. bardawil , and D. granulata . These species were selected as part of a larger screen to identify species suitable for biofuel feedstocks. An accelerated solvent extraction instrument was used for lipids and fatty acid extraction using a dichloromethane–hexane solvent system. Ultra-performance liquid chromatography coupled with mass spectrometry (MS) detection was optimized and applied to the quantitative analysis of TAG and FFA in the different algal extracts. Individual TAG were characterized structurally using direct electrospray ionization (ESI) MS and MS/MS techniques. Cationic adducts (NH 4 + ) of TAG were detected and quantified in the positive ESI MS and MS/MS modes, while the negative ESI mode was used for FFA analysis. Over 20 TAG were identified and quantified in the four Dunaliella strains. Analysis of FFA compositions demonstrated that the most abundant FFA in these four algal species were palmitic, linolenic, linoleic, and oleic acids.

Acid mine drainage (AMD), characterized by elevated levels of sulfate, acidity, and metals, is produced by the oxidation of mining-exposed minerals and is a major environmental issue. Sulfate-reducing bioreactors (SRBRs) are an attractive AMD treatment option. SRBRs contain an organic material, usually wood chips or compost, which provides a slow-release carbon substrate to support a complex anaerobic microbial community. A relationship between the microbial inoculum and bioremediation performance was established in laboratory experiments. The use of 16S rDNA-based profiling techniques established a correlation between SRBRs that performed well and the presence of three key functional groups: cellulose degraders, fermenters, and sulfate-reducing bacteria (SRB). Subsequent analyses of pilot- and field-scale SRBRs targeted the 16S gene and apsA functional gene, which is found in all SRB. Although multivariate statistical analyses of the 16S sequences of the communities did not reveal obvious differences, the apsA sequences of each SRBR were significantly different. The apsA sequences also revealed that Thiobacillus spp., which are capable of sulfur oxidation, were prevalent at the poorly performing SRBR. A novel, high throughput, biomolecular method called active community profiling (ACP) was developed and validated using model systems. ACP identifies the active members of mixed communities through the ratio of rRNA to rDNA, which is proportional to growth rate. When coupled with physiochemical analysis, ACP offers a powerful new tool to help understand microbial community dynamics. The effects of bioaugmentation and biostimulation on the community structure of AMD treatment systems were studied. Although all columns remediated AMD to a similar level, ACP analysis revealed that the active members of their communities were distinctive. It was determined that biostimulation or bioaugmentation at the top of the microbial carbon chain increased the active community diversity. This dissertation emphasizes the role of the microbial community associated with AMD remediation. Characterization of these communities with biomolecular tools at several scales has significantly advanced the understanding of the community's structure, function, and activity. The research approaches and methodologies developed have wide application, and provide unique and valuable contributions to the scientific knowledge of AMD treatment specifically, and to microbial ecology and bioremediation in general.

Three parameters important to the transesterification reaction of soy waste cooking oil to ethyl esters were optimized: molar ethanol concentration, weight fraction of the potassium hydroxide catalyst, and reaction temperature. In the course of optimizing the parameters, applicable analytical techniques which quantify the free fatty acid and water content of waste cooking oils and the components of the reaction mixture with minimal manipulation were developed and verified. The acid number and the water content of the waste cooking oil were determined to be as 3.61 ± 0.06 and 0.018 vol%, respectively. Hence, the pretreatment of waste cooking oil was not explored. The optimal conditions for the production of ethyl esters from waste cooking oil were identified to be: 145 mol% excess ethanol based on stoichiometric requirements, 1.3 wt% potassium hydroxide based on the waste cooking oil used, and a reaction temperature of 27°C. Using these optimized parameters, the mass-based ethyl ester yield was found to be 85.6%.