Published Materials Copyright (c) 2013 Purdue University All rights reserved. http://docs.lib.purdue.edu/alspub Recent documents in Published Materials en-us Thu, 24 Jan 2013 09:54:59 PST 3600 Evaluation of Biodegradability and Biodegradation Kinetics for Anionic, Nonionic, and Amphoteric Surfactants http://docs.lib.purdue.edu/alspub/76 http://docs.lib.purdue.edu/alspub/76 Mon, 19 May 2008 10:14:39 PDT The biodegradation kinetics of anionic (sodium laureth sulfate – SLES), amphoteric (disodium cocoamphodiacetate – DSCADA), and nonionic surfactants (polyalcohol ethoxylate – PAE) were assessed in this laboratory study. Similar degradation behavior was observed for all surfactants with only a fraction of the parent compound readily biodegradable. Biodegradation, as estimated by COD removal, was initially (i.e., within 24 h) rapid, however only 40–70% of the surfactant molecules were readily biodegradable. Intrinsic kinetic parameters were successfully quantified for the readily biodegradable component of the surfactant. Inhibition was not observed and microbial kinetics of SLES, DSCADA, and PAE degradation fit the Monod model well. Average μ-S curves were generated for each surfactant. Based on these results, complete degradation of the target surfactants using biological waste treatment would be limited.

Description:10 pages

]]> Sybil R. Sharvelle et al. Water Recycle and Air Revitalization Nutrient Retention Capabilities of Nile Tilapia (Oreochromis Niloticus) Fed Bio-Regenerative Life Support System (BLSS) Waste Residue http://docs.lib.purdue.edu/alspub/74 http://docs.lib.purdue.edu/alspub/74 Mon, 19 May 2008 10:14:34 PDT Nile tilapia were evaluated as a bio-regenerative sub-process for reducing solid waste potentially encountered in bio-regenerative life support systems. Ten juvenile Nile tilapia (mean weight = 2.05 g) were stocked into triplicate aquaria and fed one of seven experimental diets consisting of vegetable, bacterial, or food waste for a period of seven weeks. Weight gain (g), specific growth rate (mg/d), and daily consumption (g) was significantly higher (p < 0.05) in the control group (13.80, 281.60, and 47.49, respectively) followed by the wheat bran/wheat germ group (4.25, 86.87, and 24.24). Carbon and crude lipid retention was significantly higher (p < 0.001) in fish fed the control diet (37.99 and 68.54, respectively) followed by fish fed the wheat bran/wheat germ diet (23.19 and 63.67, respectively). Nitrogen, sulfur, and crude protein retention was significantly higher (p < 0.001) in fish fed the wheat bran/wheat germ group (40.73, 98.65, and 40.75, respectively) followed by fish fed the control diet (23.68, 21.89, and 23.68, respectively). A general loss of minerals was observed among all groups. Strong associations were observed between crude lipid retention and sulfur retention (r2 = 0.94), crude lipid retention and carbon retention (r2 = 0.92), WG and fiber content of dietary treatments (r2 = 0.92), WG and carbon retention and (r2 = 0.88), WG and lysine content of waste residues (r2 = 0.86), crude protein retention and carbon retention (r2 = 0.84), sulfur retention and crude protein retention (r2 = 0.84), and total sulfur amino acid (TSAA) content of residues and WG (r2 = 0.81). Weaker associations existed between WG and crude lipid retention (r2 = 0.77), crude fiber content and carbon retention (r2 = 0.76), and WG and methionine content of waste residues (r2 = 0.75). Additional research is needed to improve the nutritional quality of fibrous residues as a means to improve tilapia's ability to utilize these residues as a food source in bio-regenerative support systems.

Description:10 pages

]]> John G. Gonzales et al. Solid Waste Resource Recovery The Development and Performance of a Fluence Rate Distribution Model for a Cylindrical Excimer Lamp Supporting Information http://docs.lib.purdue.edu/alspub/72 http://docs.lib.purdue.edu/alspub/72 Mon, 19 May 2008 10:14:31 PDT Ultraviolet disinfection systems employing excimer lamp technology represent a suitable choice in situations where lamp mercury content is restricted, or otherwise undesirable. The XeBr* excimer lamp emits nearly monochromatic radiation at 282 nm, and dose-response experiments with Bacillus subtilis spores have shown that it is germicidally effective. A numerical model was developed to describe the fluence rate (E ) distribution emanating from a cylindrical XeBr* excimer lamp, based on liquid water or air as the surrounding medium. The E distribution model is based on physical phenomena that areknownto govern excimer lamps; the model also accounts for refraction, reflection, and absorbance effects of the quartz lamp envelope and the media surrounding the lamp. Measurements of the E distribution by local actinometry supported the validity of the numerical model. This model can be used as a component (submodel) of a more general model to simulate the behavior of photochemical reactors that employ excimer lamps as their source of electromagnetic radiation.

Description:10 pages

]]> Zorana Naunovic et al. Water Recycle and Air Revitalization An Optimization Framework to Design an ALSS http://docs.lib.purdue.edu/alspub/71 http://docs.lib.purdue.edu/alspub/71 Mon, 19 May 2008 10:14:29 PDT A life support system for manned space missions needs to meet the crewmember demands for the basic life support elements and it should process the loads (wastes) generated by the crewmembers. There are several technology options that can fulfill those requirements. Which technology to deploy, for which purpose, and at which stage of the station's evolution, is still an open question for the researchers. In this work, an optimization framework to determine the optimum technology list and the deployment schedule, given an objective such as minimum cost (ESM), for a manned space mission is proposed. The utilization of the framework is demonstrated by two example applications, Crew Exploration Vehicle (CEV) and Early Mars Base. The total ESM for the life support system predicted for the CEV mission is 595 kg for a crew of four for 14 days. The system favors supplying all the life support elements, such as oxygen, water and food, and storing all the wastes. For the Early Mars Base application, the overall life support system is completed in two separate launches. The total ESM for a 6.5-year Mars mission is 115,300 kg for a crew of six.

]]> Selen Aydogan et al. Systems Analysis and Integration Characterizing Crop-waste Loads For Solid Waste Processing http://docs.lib.purdue.edu/alspub/70 http://docs.lib.purdue.edu/alspub/70 Mon, 19 May 2008 10:14:27 PDT In long-duration, closed human habitats in space that include crop growth, one challenge that is faced while designing a candidate waste processor is the composition of solid-waste loads, which include human waste, packaging and food-processing materials, crop spoilage, and plant residues. In this work, a new modelling tool is developed to characterize crop residues and food wastes based on diet in order to support the design of solid-waste technologies for closed systems. The model predicts amounts of crop residues and food wastes due to food processing, crop harvests, and edible spoilage. To support the design of solid-waste technologies, the generation of crop residues and food wastes was characterized for a 600-day mission to Mars using integrated menu, crop, and waste models. The three sources of plant residues and food waste are identified to be food processors, crop harvests, and edible spoilage. Of these waste streams, the largest generator was crop harvests, especially vines and leaves of sweet potato, which accounted for over 60% of solid waste by mass.

]]> James F. Russell et al. Systems Analysis and Integration Biodegradation of Polyalcohol Ethoxylate by a Wastewater Microbial Consortium http://docs.lib.purdue.edu/alspub/69 http://docs.lib.purdue.edu/alspub/69 Mon, 19 May 2008 10:14:25 PDT Polyalcohol ethoxylate (PAE), an anionic surfactant, is the primary component in most laundry and dish wash detergents and is therefore highly loaded in domestic wastewater. Its biodegradation results in the formation of several metabolites and the fate of these metabolites through wastewater treatment plants, graywater recycling processes, and in the environment must be clearly understood. Biodegradation pathways for PAE were investigated in this project with a municipal wastewater microbial consortium. A microtiter-based oxygen sensor system was utilized to determine the preferential use of potential biodegradation products. Results show that while polyethylene glycols (PEGs) were readily degraded by PAE acclimated microorganisms, most of the carboxylic acids tested were not degraded. Biodegradation of PEGs suggests that hydrophobe-hydrophile scission was the dominant pathway for PAE biodegradation in this wastewater community. Ethylene glycol (EG) and diethylene glycol (DEG) were not utilized by microbial populations capable of degrading higher molecular weight EGs. It is possible that EG and DEG may accumulate. The microtiter-based oxygen sensor system was successfully utilized to elucidate information on PAE biodegradation pathways and could be applied to study biodegradation pathways for other important contaminants.

Description:7 pages

]]> Sybil E. Sharvelle et al. Water Recycle and Air Revitalization Water and Energy Transport of Crops Under Different Lighting Conditions http://docs.lib.purdue.edu/alspub/68 http://docs.lib.purdue.edu/alspub/68 Mon, 19 May 2008 10:14:21 PDT When high-intensity discharge (HID) electric lamps are used for plant growth, system inefficiencies occur due to an inability to effectively target light to all photosynthetic tissues of a growing crop stand, especially when it is closed with respect to light penetration. To maintain acceptable crop productivity, light levels typically are increased thus increasing heat loads on the plants. Evapotranspiration (ET) or transparent thermal barrier systems are subsequently required to maintain thermal balance, and power-intensive condensers are used to recover the evaporated water for reuse in closed systems. By accurately targeting light to plant tissues, electric lamps can be operated at lower power settings and produce less heat. With lower power and heat loads, less energy is used for plant growth, and possibly less water is evapotranspired. By combining these effects, a considerable energy savings is possible. To assess potential energy savings, the authors examined the costs of water and energy transport of cowpea and soybean under four different lighting conditions: overhead metal halide lamps at low light (350 umol/m\u2/s), overhead high pressure sodium lamps at high light (870 umol/m\u2/s), an overhead close-canopy, light-emitting diode (LED)-based system at low light (300 umol/m\u2/s), and an intracanopy LED-based system at low light (300 umol/m\u2/s). The authors used data from published and ongoing studies in the system analysis. When comparing the different lighting conditions, different amounts of total biomass were produced but similar ET rates were found, so lighting condition was not found to impact ET. Overall, intracanopy, LED-based lighting provided the lowest energy costs.

]]> James F. Russell et al. Edible Biomass/Crop Production Optimizing Edible Fungal Growth and Biodegradation of Inedible Crop Residues Using Various Cropping Methods http://docs.lib.purdue.edu/alspub/67 http://docs.lib.purdue.edu/alspub/67 Mon, 19 May 2008 10:14:20 PDT Long-term manned space flights to Mars require the development of an advanced life support (ALS) ecosystem including efficient food crop production, processing and recycling waste products thereof. Using edible white rot fungi (EWRF) to achieve effective biomass transformation in ALS requires optimal and rapid biodegradative activity on lignocellulosic wastes. We investigated the mycelial growth of Lentinula edodes and Pleurotus ostreatus on processed residues of various crops under various cropping patterns. In single cropping, mycelial growth and fruiting in all strains were significantly repressed on sweet potato and basil. However, growth of the strains was improved when sweet potato and basil residues were paired with rice or wheat straw. Oyster mushroom (Pleurotus) strains were better than shiitake (L. edodes) strains under single, paired, and mixed cropping patterns. Mixed cropping further eliminated the inherent inhibitory effect of sweet potato, basil, or lettuce on fungal growth. Co-cropping fungal species had a synergistic effect on rate of fungal growth, substrate colonization, and fruiting. Use of efficient cropping methods may enhance fungal growth, fruiting, biodegradation of crop residues, and efficiency of biomass recycling.

]]> Leopold M. Nyochembeng et al. Edible Biomass/Crop Production Nitrogen Amendment Enhances Edible White Rot Fungal Growth and Biodegradation of Containerized Inedible Crop Residues http://docs.lib.purdue.edu/alspub/66 http://docs.lib.purdue.edu/alspub/66 Mon, 19 May 2008 10:14:17 PDT Edible white rot fungi have been proposed for selective plant biomass transformation and recycling in a sustainable advanced life support (ALS) ecology needed for extraterrestrial expeditions, such as the mission to Mars. Food waste slurry was incorporated into artificial fungal culture media to test for strain tolerance, while urea and food waste were amended in processed wheat and rice straw, as sources of N, to enhance fungal growth, biodegradation, and recycling of the crop wastes. Mycelial growth in food waste-amended artificial culture media decreased with an increase in food waste concentration, while tolerance to high food waste concentration under these conditions was species dependent. Pleurotus ostreatus ""Grey Dove"" and P. pulmonarius were most efficient in degradation when food waste was supplemented at 80% (v/v) in wheat straw. However, when both species were cocultured, addition of food waste to wheat straw did not improve degradation efficiency. Mycelial growth and colonization of P. cornucopiae "Golden Oyster" was enhanced in food waste-amended rice straw compared to growth in the control. Basidiocarp production occurred only in the amended media; however, the quantity of fruit bodies decreased with increased concentration of food waste in the amended rice straw. Enriching wheat straw with urea stimulated fruiting only in "Grey Dove" at 50-60 days after inoculation. P. ostreatus "Blue Dolphin" did not fruit in amended wheat straw despite prolific mycelial colonization of the substrate. Amending inedible crop residues with organic or mineral N at predetermined rates may enhance edible white rot fungal biodegradation of the lignocellulosic residues if tolerant strains are used.

Description:6 pages

]]> Leopold M. Nyochembeng et al. Edible Biomass/Crop Production Surface Modification of Nanofiltration Membranes by Ion Implantation http://docs.lib.purdue.edu/alspub/65 http://docs.lib.purdue.edu/alspub/65 Mon, 19 May 2008 10:14:15 PDT This study involves modifying the surface of nanofiltration (NF) membranes by ion implantation for increased salt rejection. F- ions were implanted on the surface of commercially available nanofiltration membranes to increase the negativity of the membrane surfaces. The objective was to increase the Donnan exclusion effect and thus increasing the salt rejection by the modified membranes. A composite polyamide NF membrane (NF 90 Filmtec) and a cellulose acetate NF membrane (SP 28 Osmonics) were implanted with F? ions at two different intensities--1E10 and 5E10 atoms/cm2. Zeta potential measurements of the unmodified membranes and modified membranes show higher negativity with an increased intensity of ion implantation. Multicomponent salt permeation experiments were performed with the three types of membranes--the unmodified membrane and the two types of modified ones for both NF 90 and SP 28. The results show a decrease of solute flux for all the ions through the modified membranes when compared to that with the unmodified membrane. Initial experiments show no leaching of F? ions into the solution. Therefore, ion implantation on nanofiltration membrane surfaces is a novel technique to increase the salt rejection property of membranes.

Description:8 pages

]]> Parna Mukherjee et al. Water Recycle and Air Revitalization Abiotic Ammonia Mass Transfer in a Biotrickling Filter http://docs.lib.purdue.edu/alspub/64 http://docs.lib.purdue.edu/alspub/64 Mon, 19 May 2008 10:14:11 PDT Abiotic ammonia mass transfer phenomena within a novel biotrickling filter was investigated. The wastestream consists of graywater (hygiene, shower, laundry and food prep water) and waste gas from an upstream solids treatment unit. The bioprocessor is designed to promote absorption of waste gas and biodegradation of contaminants. Following the assumption that advection, diffusion and subsequent bioreaction(s) are independent, transport processes may be analyzed separately and thus only the abiotic mass transfer of ammonia and the effect of surfactants are considered herein. Operating conditions included various gas-phase and liquid-phase flowrates. The experiments were conducted in the presence and absence of the three surfactants of concern, one amphoteric, one anionic, and one nonionic to determine the effect of the surfactants on waste gas absorption. Results indicated that surfactants did not play a significant role in the abiotic mass transfer of ammonia within the system (p-value = 0.998). The data were analyzed using various mass transfer correlations to ensure the validity of this conclusion. Multicomponent gas mixtures and the presence of biofilm(s) during future studies may potentially alter ammonia mass transfer and future research will take this into account.

Description:9 pages

]]> Eric McLamore et al. Water Recycle and Air Revitalization Simultaneous Biodegradation of a Two-Phase Fluid: Biofilm Discoloration Issues http://docs.lib.purdue.edu/alspub/63 http://docs.lib.purdue.edu/alspub/63 Mon, 19 May 2008 10:14:09 PDT Three replicate aerobic-heterotrophic biotrickling filters were designed to promote the simultaneous biodegradation of graywater and a waste gas containing NH\d3, H\d2S and CO\d2. Upon visual observation of discolored solids, it was originally hypothesized that gas-phase CO\d2 concentrations were excessive, causing regions of anoxic zones to form within the biotrickling filters. Observed discolored (black) biofilm of this nature is typically assumed to be either lysed bacterial cells or anaerobic regions, implying alteration of operational conditions. Solid (biofilm) samples were collected in the presence and absence of gas-phase wastestream(s) to determine if the gas-phase contaminants were contributing to the solid-phase discoloration. Two sets of experiments (shaker flask and solids characterization) were conduced to determine the nature of the discolored solids. Results indicated that the discolored solids were neither anaerobic bacteria nor lysed cells. The solids were organic in nature and contain active aerobic-heterotrophic bacteria. Future work will attempt to characterize the discolored solid-phase more accurately.

]]> Eric McLamore et al. Water Recycle and Air Revitalization Strawberry Cultivar Analysis: Temperature and Pollination Studies http://docs.lib.purdue.edu/alspub/62 http://docs.lib.purdue.edu/alspub/62 Mon, 19 May 2008 10:14:05 PDT Strawberry is a life-support-system candidate crop species that is long-lived, asexually propagated, and can bear large quantities of fruit high in sugar and antioxidant content. Strawberries of four-day-neutral cultivars ("Tribute," "Tristar," "Seascape," and "Fern") and one everbearing cultivar ("Cavendish") were grown under greenhouse conditions or varying temperature regimes in three growth chambers. Flowers in growth chambers were hand pollinated three-times weekly with stored pollen, and ripe berries were harvested, counted, weighed, and tested organolepticly. In the greenhouse, two different pollination treatments were compared, while another group of plants was left unpollinated, receiving only occasional mechanical stimulation from normal greenhouse airflow, berry harvest, and plant maintenance. A second group was pollinated with a vibrating wand, and a third group was hand pollinated with stored pollen. The time required for each method was compared along with berry productivity.

Description:15 pages

]]> Gioia Donna Massa et al. Edible Biomass/Crop Production Evaluation of Fish Meal-Free Diets for First Feeding Nile tilapia, Oreochromis Niloticus http://docs.lib.purdue.edu/alspub/61 http://docs.lib.purdue.edu/alspub/61 Mon, 19 May 2008 10:14:03 PDT A study was conducted to evaluate fish meal-free practical diets, with and without amino acid supplementation, for the rearing of first feeding Nile tilapia, Oreochromis niloticus. A basal diet was formulated that appeared marginally deficient in lysine, methionine and threonine; thus, experimental diets were supplemented with all possible combinations of those three essential amino acids. Diets contained 45% crude protein and 12% lipid. Diets were fed to apparent satiation four times daily (0800, 1100, 1400, and 1700 hours) for a period of 30 days. No significant differences (P < 0.05) in specific growth rate, weight gain, apparent consumption, food conversion ratio or survival were observed. A significant difference (P < 0.01) in protein retention was observed between fish fed the positive control diet (51.84%) and experimental treatments (22.80-35.17%). This initial evaluation of fish meal-free practical diets for first feeding Nile tilapia demonstrates the potential for eliminating fish meal in diets for larval tilapia, but additional research appears needed to enhance retention of amino acids.

Description:11 pages

]]> John M. Gonzales et al. Solid Waste Resource Recovery Nile Tilapia Oreochromis Niloticus as a Food Source in Advanced Life Support Systems: Initial Considerations http://docs.lib.purdue.edu/alspub/60 http://docs.lib.purdue.edu/alspub/60 Mon, 19 May 2008 10:14:01 PDT Maintenance of crew health is of paramount importance for long duration space missions. Weight loss, bone and calcium loss, increased exposure to radiation and oxidative stress are critical concerns that need to be alleviated. Tilapia are currently under evaluation as a source of food and their contribution to reducing waste in advanced life support systems (ALSS). The nutritional composition of tilapia whole bodies, fillet, and carcass residues were quantitatively determined. Carbon and nitrogen free-extract percentages were similar among whole body (53.76% and 6.96%, respectively), fillets (47.06% and 6.75%, respectively), and carcass (56.36% and 7.04%, respectively) whereas percentages of N, S, and protein were highest in fillet (13.34, 1.34, and 83.37%, respectively) than whole body (9.27, 0.62, and 57.97%, respectively) and carcass (7.70, 0.39, and 48.15%, respectively). Whole body and fillet meet and/or exceeded current nutritional recommendations for protein, vitamin D, ascorbic acid, and selenium for international space station missions. Whole body appears to be a better source of lipids and n-3 fatty acids, calcium, and phosphorous than fillet. Consuming whole fish appears to optimize equivalent system mass compared to consumption of fillets. Additional research is needed to determine nutritional composition of tilapia whole body, fillet, and carcass when fed waste residues possibly encountered in an ALSS.

Description:6 pages

]]> John M. Gonzales et al. Solid Waste Resource Recovery Loading Balance and Influent pH in a Solids Thermophilic Aerobic Reactor http://docs.lib.purdue.edu/alspub/59 http://docs.lib.purdue.edu/alspub/59 Mon, 19 May 2008 10:13:59 PDT The Bioregenerative Air Treatment for Health system has been proposed for Advanced Life Support (ALS) planetary base applications. The system will be operated as a biotrickling filter to simultaneously treat graywater and waste gas. Preliminary experiments have focused on carbon removal from a graywater simulant. Six bench scale biotrickling filter reactors were constructed and monitored continuously. After a reactor startup phase of 40 days, the average total organic carbon (TOC) removal for reactors packed with Tri-packs\sR packing material was 62%. A second set of experiments was designed to evaluate TOC removal using different packing materials (Bee-cell and Biobale). It was hypothesized that the alternative packing materials would reduce the effects of channeling in the reactors, thus improving TOC removal. However, TOC removal did not significantly improve during the second set of experiments. Of note is that start-up performance was higher in reactors packed with Tri-packs\sR than other reactors. These results indicate that selection of packing material may be an important design parameter for reduction of reactor start-up period and associated off- line time.

]]> Dawn R. Whitaker et al. Solid Waste Resource Recovery Characterization of Effluent from Biological Trickling Filters Treating Graywater in Advanced Life Support Systems http://docs.lib.purdue.edu/alspub/58 http://docs.lib.purdue.edu/alspub/58 Mon, 19 May 2008 10:13:58 PDT Six bench scale biological trickling filter reactors were constructed and operated for simulated advanced life support (ALS) graywater recycling. In an initial evaluation, after a reactor startup phase of 40 days, the average TOC removal for six replicate reactors packed with Tri-packs packing material was 65%. A second set of experiments was designed to assess TOC removal using several types of packing material (B-cell and Biobale). It was hypothesized that alternative packing materials would reduce the effects of channeling in the reactors, thus improving TOC removal. However, the TOC removal was not substantially improved during the second set of experiments. Additionally, recirculation rates were varied and effects to TOC removal were tracked. These modifications also did not result in improved reactor performance. Therefore, a partial characterization of reactor effluent was conducted to determine if the plateau in TOC removal was a result of mass transfer limitations from inefficient lateral dispersion of water through the packing material. The results indicate that degradation by-products may not be readily biodegradable in this system.

Description:10 pages

]]> Sybil Sharvelle et al. Water Recycle and Air Revitalization Evaluation of Biological Trickling Filter Performance for Graywater Treatment in ALS Systems http://docs.lib.purdue.edu/alspub/57 http://docs.lib.purdue.edu/alspub/57 Mon, 19 May 2008 10:13:55 PDT The Bioregenerative Air Treatment for Health system has been proposed for Advanced Life Support (ALS) planetary base applications. The system will be operated as a biotrickling filter to simultaneously treat graywater and waste gas. Preliminary experiments have focused on carbon removal from a graywater simulant. Six bench scale biotrickling filter reactors were constructed and monitored continuously. After a reactor startup phase of 40 days, the average total organic carbon (TOC) removal for reactors packed with Tri-packs\sR packing material was 62%. A second set of experiments was designed to evaluate TOC removal using different packing materials (Bee-cell and Biobale). It was hypothesized that the alternative packing materials would reduce the effects of channeling in the reactors, thus improving TOC removal. However, TOC removal did not significantly improve during the second set of experiments. Of note is that start-up performance was higher in reactors packed with Tri-packs\sR than other reactors. These results indicate that selection of packing material may be an important design parameter for reduction of reactor start-up period and associated off- line time.

Description:7 pages

]]> Sybil E. Sharvelle et al. Water Recycle and Air Revitalization Influence of Support Media Characteristics on Biofilm Activity in Graywater Treatment Systems for Advanced Life Support http://docs.lib.purdue.edu/alspub/56 http://docs.lib.purdue.edu/alspub/56 Mon, 19 May 2008 10:13:53 PDT Advanced life support systems for long-duration space missions will require efficient recycling of water and air. Biological treatment systems may be used as the initial process in a multistep recycling system. Biofilm reactors (or biotrickling filters) have been shown to be effective for treatment of air and water. A major design consideration for these reactors is the selection of biofilm support media. The main objective of this research was to evaluate the effect of three commercially available support media on biofilm activity. Biofilm activity was quantified in terms of microbial respiration, or specifically, carbon dioxide production. Results indicate that carbon mineralization did not differ significantly between media types when data were evaluated based on media volume. However, there was a significant difference in microbial activity when assessed with media surface area as an input value. The results suggest that suspended microorganisms may have contributed significantly to the carbon mineralization in the reactor. Therefore, when predicting performance of submerged biofilm reactors, liquid or media volume should be used as a key model parameter rather than media surface area. This information could prove to be useful when selecting support media and reactor volume for biofilm graywater treatment reactors."

Description:5 pages

]]> Neepa Shah et al. Water Recycle and Air Revitalization Urine Processing for Water Recovery via Freeze Concentration http://docs.lib.purdue.edu/alspub/55 http://docs.lib.purdue.edu/alspub/55 Mon, 19 May 2008 10:13:51 PDT Resource recovery, including that of urine water extraction, is one of the most crucial aspects of long-term life support in interplanetary space travel. This paper will consequently examine an innovative approach to processing raw, undiluted urine based on low-temperature freezing. This strategy is uniquely different from NASA's current emphasis on either 'integrated' (co-treatment of mixed urine, grey, and condensate waters) or 'high temperature' (i.e., VCD [vapor compression distillation] or VPCAR [vapor phase catalytic ammonia removal]) processing strategies, whereby this liquid freeze-thaw (LiFT) procedure would avoid both chemical and microbial cross-contamination concerns while at the same time securing highly desirable reductions in likely ESM levels. The involved freeze concentration methodology is a low energy process that focuses on the nucleation of pure ice crystals followed by a ripening effect of those crystals and subsequent washing to achieve high extraction efficiencies. A theoretical water recovery value of approximately 88% has been determined based on the eutectic points of the expected urine constituents. Overall, this research paper will focus on several aspects of freeze concentration, including an overview of the basic technology and its various pragmatic applications, as well as a theoretical comparison of model percent recovery rates relative to observed experimental operational values. Detailed testing results will also be presented to confirm the observed low-level migration of inorganic, organic, and biological contaminants into the product water.

]]> Jeffrey M. Schmidt et al. Water Recycle and Air Revitalization