Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2001-10-19
2004-06-22
Upton, Christopher (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S621000, C210S150000, C210S195100, C210S195200
Reexamination Certificate
active
06752926
ABSTRACT:
BACKGROUND OF THE INVENTION
Biochemical oxidation of carbonaceous and nitrogenous substrates, in aqueous waste streams, is typically mediated by microorganisms capable of catalyzing the oxidative processes under conditions ranging from strict aerobiosis to strict anaerobiosis. The selection of the specific process environment depends on the nature of the substrates, their concentration and treatment objectives. High strength wastewater is characterized by high substrate concentrations, as measured by the chemical oxygen demand (COD) or the five-day biochemical oxygen demand (BOD5), and high nitrogen content, as measured by ammonia-, nitrite- or nitrate-nitrogen. Conversion of BOD5 to carbon dioxide and water, and transformation of ammonia to nitrite and nitrate in a process termed nitrification, requires a supply of oxygen sufficiently high to satisfy the stoichiometric requirements of these processes.
Biological processing of high strength wastewater in terrestrial or space environments presents serious challenges, stemming mainly from mass transfer limitations of substrate and oxygen. Further, a major issue in space applications is the absence of gravity which introduces problems associated with separation between solid-liquid and liquid-gas phases.
Immobilized, cell packed bed bioreactors (ICPB) have been used extensively for the treatment of wastewater on earth and can provide solutions to problems associated with microgravity. Conceptual models of advanced life support (ALS) integrated systems design mandate approximately 100% closure with respect to the water loop Drysdale A. E., et al., “A More Completely Defined CELSS”, SAE Paper 941292, 24th International Conference on Environmental Systems and 5th European Symposium on Space Environmental Control System, Friedrichshafen, Germany, Jun. 20-23, 1994.). Water reclamation from various aqueous streams and reuse is thus imperative. Water rich liquid streams in space/space vehicle habitats include washwater, utility water (food preparation, laundry), urine and condensate water. Mixtures of the first two streams (washwater, utility water) are commonly termed greywater. Estimated quantities of urine and greywater vary in the range of between 1.3-2.1 liters of urine waste and 20-30 liters of greywater waste per person per day. (Wieland P. O., “Designing for Human Presence in Space: An Introduction to Environmental Control and Life Support Systems”, NASA Reference Publication 1324, 1994.; Wydeven T. and Golub M. A., “Generation Rates and Chemical Composition of Waste Streams in a Typical Crewed Space Habitat”, NASA Technical Memorandum 102799, Ames Research Center, 1990). With the exception of condensate water which is low in organic content, the other liquid streams contain varying amounts of organic loads and require treatment prior to any possible reuse. Various reuse scenarios include utilization of the reclaimed water as hydroponic solution water, utility water, or potable water. Evidently, each of these reuse scenarios dictates and sets the desired treatment objectives. These objectives include, but are not limited to: organic carbon removal, nutrient reclamation and reuse in hydroponic solutions, and water reclamation. Essentially the first two objectives can be summarized as carbon oxidation and nitrification. Research conducted over the last ten years has shown that biological processes for treatment of urine, condensate, and grey water combined streams have a demonstrated potential for use as a primary water processor (Petrie G. E., et al., “Development of Immobilized Cell Bioreactor Technology for Water Reclamation in a Regenerative Life Support System”, SAE Paper 911503, 21st International Conference on Environmental Systems, San Francisco, Jul. 15-18, 1991; Petrie G. E., et al., “Immobilized Cell Bioreactors for Water Reclamation: Process Stability and Effect of Reactor Design”, SAE Paper 921227, 22nd International Conference on Environmental Systems, Seattle, Jul. 13-16, 1992.) or a trace polisher in an integrated bioregenerative life support water recovery system (Miller G. P. et al., “Further Applications of the Use of Biological Reactors to Remove Trace Hydrocarbon Contaminants from Recycled Water”, SAE Paper 921273, 22nd International Conference on Environmental Systems, Seattle, Jul. 13-16, 1992; Miller G. P. et al., “Using Biological Reactors to Remove Trace Hydrocarbon Contaminants from Recycled Water”, SAE Paper 911504, 21st International Conference on Environmental Systems, San Francisco, Jul. 15-18, 1991). Because of the well established performance reliability, small energy and volumetric requirements, various configurations of immobilized cell bioreactors have been preferred over their suspended growth counterparts. Collaborative work performed by NASA and aerospace contractors has focused on immobilized cell bioreactors operating as plastic media packed beds. Two-stage packed bed bioreactors containing porous and non-porous plastic media accomplishing carbon oxidation in the first stage and nitrification in the second were initially studied (Verostko C. E., et al., “A Hybrid Regenerative Water Recovery System for Lunar/Mars Life Support Applications”, SAE Paper 921276, , 22nd International Conference on Environmental Systems, Seattle, Jul. 13-16, 1992). The performance of these reactors with respect to both chemical oxygen demand (COD), and urea degradation at hydraulic retention times (HRT) in the range of 24-48 hr was satisfactory (greater than 97% and 99%, respectively) but decreased significantly for HRTs in the range of 12-24 hr (65% and 91%, respectively) (Petrie G. E., et al., “Immobilized Cell Bioreactors for Water Reclamation: Process Stability and Effect of Reactor Design”, SAE Paper 921227, 22nd International Conference on Environmental Systems, Seattle, Jul. 13-16, 1992). An immobilized cell bioreactor (ICB) essentially consisting of a foam covered plate reactor was also studied in parallel. The parallel plate reactor performance was over 95% and 99% total organic carbon (TOC) and urea reduction for all HRTs in the range of 12-24 hours. Full-scale experiments for both bioreactor types verified previous findings (Nacheff-Benedict M. S. et al., “An Integrated Approach to Bioreactor Technology Development for Regenerative Life Support Primary Water Processor”, SAE Paper 941397, 24th International Conference on Environmental Systems and 5th European Symposium on Space Environmental Control System, Friedrichshafen, Germany, Jun. 20-23, 1994).
Immobilized cell bioreactors with packed or fluidized bed, provide a unique environment for microbial growth resulting in high biomass concentrations. Packing materials commonly used include ceramic saddles, stainless steel wire spheres, polypropylene toroids, reticulated polyester foams, matted reticulated polypropylene sheets, polypropylene strands and sand. The main features of immobilized cell bioreactors are the support media for microbial attachment with larger surface area which are better for conversion efficiency; the absence of a microbial wash-out flow-rate, and the elimination of the need for concentrated biomass recycle from a clarifier. The advantages of these reactor configurations over conventional, completely stirred tank reactors (CSTR) systems for organic removal and nitrification/denitrification are well established. Biomass concentrations as high as 5-40 g/L of reactor volume have been reported when using solid support particles (Cooper, R. F. and B. Atkinson. Editors of: Biological Fluidized Bed Treatment of Water and Wastewater. Ellis Horwood Limited Publishers, 1981). High biomass concentrations greatly enhance process efficiency resulting in substantial reductions in treatment time and reactor volume. ICBPs can operate both in aerobic and oxygen limiting modes. A major problem with the operation of such aerobic reactors is oxygen distribution and gaseous by-product formation. Phase separation in packed beds under microgravity conditions, has been a major problem.
Greywater generated in closed environments such as a space station, a
Christodoulatos Christos
Korfiatis George P.
McCarter & English LLP
Trustees of Stevens Institute of Technology
Upton Christopher
LandOfFree
Method and apparatus for treatment of wastewater does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for treatment of wastewater, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for treatment of wastewater will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3309601