Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2000-07-19
2002-04-02
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S617000, C210S621000, C210S629000, C210S631000, C210S760000
Reexamination Certificate
active
06365048
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
None
BACKGROUND OF THE INVENTION
(1). Field of the Invention
The present invention relates to a process which enables the treatment of organic matter contaminated drinking water. In particular, the present invention uses a combination of the addition of a carbon source to a fluidized bed bioreactor and ozonated organic matter to biodegrade the ozonated organic matter and carbon source and thus purify the water.
(2). Description of Related Art
The use of beds containing microorganisms in an aerobic biological environment which degrades pollutant organic matter in water is well known in the prior art. Further, the use of ozone to oxidize the organic matter for biodegradation is well known in the prior art. U.S. Pat. No. 5,851,399 to Leitzke describes such a process using a fixed bed reaction vessel. U.S. Pat. No. 3,779,909 to Wisfeld et al also describes a similar fixed bed process. Various other patents are as follows: U.S. Pat. No. 5,954,963 to Matheson; U.S. Pat. No. 5,942,118 to Besten; U.S. Pat. No. 5,885,826 to Worden et al; U.S. Pat. No. 5,711,887 to Gastman et al; U.S. Pat. No. 5,512,178 to Dempo; U.S. Pat. No. 5,505,856 to Campen et al; U.S. Pat. No. 5,466,374 to Bachhofer et al; U.S. Pat. No. 5,346,617 to Costello; U.S. Pat. No. 5,336,413 to van Staveren; U.S. Pat. No. 5,211,847 to Kanow; U.S. Pat. No. 4,693,827 to Mordorski U.S. Pat. No. 4,255,266 to Moreaud et al; U.S. Pat. No. 4,178,239 to Lowther; and U.S. Pat. No. 3,836,456 to Fries.
U.S. Pat. No. 4,693,827 Mordoski describes a fixed bed method for accelerating the start-up of biological nitrification systems for wastewater treatment and preventing reducing the effects of toxic and inhibitory materials or excursions of pH, temperature, or dissolved oxygen upon nitrifying organisms. A rapidly metabolized soluble or miscible organic material containing little or no nitrogen is added to the carbon-consuming step of the process. Heterotrophic organisms consume the added material together with soluble ammonia to generate additional organisms. The soluble ammonia concentration in the wastewater is reduced to a nontoxic, less toxic, or less inhibitory level. The goal is to increase the removal of ammonia nitrogen from wastewater by adding rapidly metabolized carbon source. The carbon source provides growth of heterotrophic microorganisms that consume ammonia nitrogen which is incorporated into cellular matter (the C:H:O:N ratio of bacterial cells is typically about 52:6:26:12). This reference describes the use of additional rapidly metabolized carbon source to increase biomass concentration; the use of chemical compounds such as carbon supplements (alcohols, organic acids, and the like) for the degradation; and that the carbon source is added to the water stream just prior to or directly to the stage which removes carbonaceous materials from water. The patented method pertains to the removal of ammonia nitrogen, but not to the removal of organic matter initially present in water.
U.S. Pat. No. 5,954,963 to Matheson describes a fixed bed process and apparatus for biologically treating water without using ozone. The inventive process preferably comprises the steps of: (a) adding a sulfur-containing oxygen scavenger to the water in an amount effective for at least reducing the amount of dissolved free oxygen in the water; (b) removing at least a portion of a substance from the water by exposing the water to microorganisms effective for biologically removing the substance therefrom; and (c) feeding a biostimulant to the microorganisms effective for increasing the rate at which step (b) occurs. The inventive apparatus preferably comprises a system for adding the sulfur-containing oxygen scavenger to the source water stream and a system for feeding the biostimulant to the microorganisms. The invention particularly relates to processes and apparatuses for the biological denitrification of water.
The patent describes the use of a biostimulant to the microorganisms to increase the rate at which a substance is removed from water; the use of low molecular weight organic compounds as carbon supplements for the purpose of invention (alcohols, organic acids, and the like); and the use of a carbon source added to the water stream at a point located at a very short distance upstream of the bioreactor.
The process of Matheson pertains to biological denitrification of water, and not the removal of organic matter present in water. The Matheson process is not capable of effectively removing organic matter (particularly humic substances, which are disinfection by-product precursors) from water. This is because most of the organic matter present in water cannot be effectively degraded by purely biological means. As a result, while microorganisms consume the biostimulant, little or no removal of organic matter present in water occurs. No ozonation is used first to convert nonbiodegradable organic materials into biodegradable organic matter and then “stimulated” biodegradation is used to increase the rate at which this biodegradable organic matter is removed by microorganisms. In Matheson, the carbon source (an organic compound) may be added.
U.S. Pat. No. 5,851,399 to Leitzke describes a fixed bed process which serves for treating water polluted with pollutants which can only be degraded with difficulty by purely biological means. The water is circulated through a reactor vessel arrangement in which it is treated with ozone which causes a preliminary oxidation of the pollutants. The water passes into a vessel arrangement containing an aerobic biological treatment which, owing to the preliminary oxidation of the pollutants, is able to degrade these further. It can be inferred from the description, that water alternately passes through ozonation and biodegradation stages so that ozone is used to break down nonbiodegradable materials and convert them into biodegradable materials, which are removed at the biodegradation stage.
Leitzke describes the use of recirculation through ozonation and biodegradation stages. The Leitzke process was not effective for either the removal of natural organic matter present in water or producing biologically stable water. This is because ozonation of natural organic matter produces a significant amount of slowly biodegradable organic matter, which is difficult to remove by biodegradation. There is no disclosure of a rapidly metabolized carbon source which increases the rate at which these biodegradable materials are biodegraded, thus, significantly enhancing the effect of recirculation on process efficiency.
U.S. Pat. No. 5,466,374 to Bachhofer et al and Locher describes a fixed bed process for purifying polluted water containing organic nutrients for microorganisms, the process including (a) mixing the organically polluted water intensively with ozone in an ozone treatment unit; (b) adding to the water of step (a) at least one compound containing sulfur, which at least one compound containing sulfur is bioavailable for assimilation by at least aerobic microorganisms; and (c) passing water of step (b) through a filter composed of a plurality of layers. The process may optionally include treating water after step (c) with ozone in an ozone water treatment unit in order to oxidize residual bioavailable sulfur. The compound containing sulfur is preferably added in an amount which is effective to at least eliminate sulfur deficiency of the aerobic microorganisms and promote growth of a biofilm in the filter thereby contributing to biological mineralization of the organic nutrients. The goal is to increase the bioavailability of organic pollutants by means of ozone and to increase the rate of biodegradation by adding sulfur containing compounds that promotes growth of biomass.
Bachhofer et al describe the use of ozone to convert nonbiodegradable materials into biodegradable organic matter; the use of biodegradation to remove biodegradable organic matter; and the addition of biostimulants to increase biodegradation rate by promoting growth of biomass.
The Bachhofer et al process i
Masten Susan Jane
Yavich Alexander A.
Board of Trustees of Michigan State University
McLeod Ian C.
Prince Fred
Simmons David A.
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