Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
1999-07-30
2002-08-06
Barry, Chester T. (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S610000, C210S611000, C210S620000, C210S631000, C210S153000, C210S154000, C210S172300, C210S199000, C210S916000
Reexamination Certificate
active
06428701
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to bioremediation of wastewater, and more particularly to a method and apparatus for treating wastewater flowing thorough a sewer with a solid or dry bioremediation preparation.
BACKGROUND OF THE INVENTION
Public wastewater collection and treatment systems typically consist of networks of underground pipes and conduits, wet wells, and pumping/lift stations that carry wastewater (e.g., waste from sanitary sewer systems) to a wastewater treatment plant. After entering the treatment plant, the wastewater is commonly subjected to primary, secondary and tertiary treatment processes to remove solid matter and other substances from the wastewater.
Public wastewater collection and treatment systems can be subject to a number of expensive and noxious problems. Such problems typically result from or consist of a) build-up of congealed grease or organic matter within pipes or other conduits, b) the formation of grease layers known as “mats” on the surfaces of wastewater that pools within wet wells or lift stations; c) anaerobic septic conditions, d) bad odors due to the production of hydrogen sulfide and/or other gasses, e) acidic corrosion due to hydrogen sulfide gas, and f) disease-causing bacteria. If left unchecked, these conditions can cause expensive pipe and equipment damage, pipe blockages, backed up sewer lines, raw sewage spills and health problems in humans and/or animals within the community.
Various methods of coping with these problems have been tried in the past. The following are examples of such prior methods of coping with these problems:
i. Mechanical Dislodgement or Purging of Obstructions
Various mechanical processes have been used to dislodge and remove built-up coatings of congealed grease, sludge deposits, oil and soap in sewer lines and lift stations. The mechanical processes include the use of water pressure jets, vacuum trucks, “roto-rooting” and a process known as “pigging” or “balling” where a ball is forced and/or pulled through the wastewater line. These mechanical processes are high in labor, equipment and removal costs. The dislodged pieces of material have to be collected and taken to a disposal site.
ii. Chemical Treatments
Solvent and enzyme products can be used to liquefy and disperse the grease. The required products are costly. This method often times does not reduce the oil and grease in the collection system, but merely passes the problem downstream as the oil and grease may tend to re-solidify, thereby re-coagulating in pipes and pump stations or re-forming in the wastewater treatment plant.
Chemicals such as calcium nitrate, sodium nitrate, chlorine, hydrogen peroxide, caustic soda, lime and iron salts can be used in the short-run to control the bacteria and other conditions responsible for the generation of odorous and corrosive hydrogen sulfide gas. The use of chemicals in sufficient quantities in the long-run is not only very expensive, but there are operational and safety problems. Chemicals can kill the beneficial microorganisms which are the heart of the waste treatment plant, and create ecological problems beyond the plant. However, the currently available chemical storage and delivery apparatus useable for this purpose typically require an above-ground storage structure as well as a source of electrical power, which may be unavailable at many locations in a municipal wastewater treatment system. Moreover, chlorine is highly toxic and can form hazardous compounds such as trihalomethanes (THMs) which are known carcinogens. Hydrogen peroxide is an oxidizing agent less harmful than chlorine, but it has safety and handling issues. The same applied to caustic soda and iron salts, which are corrosive in their own right and can damage plant and equipment like the hydrogen sulfide gas they are supposed to mitigate.
iii. Microbiological Treatments
Another approach involves the use of naturally occurring beneficial microorganisms and catalysts or biostimulation additives (e.g. mixtures or complexes of vitamins, amino acids, enzymes, minerals, organic acids and nutrients) that can stimulate the growth of aerobic and facultative microorganisms indigenous to the system or those aerobic and facultative organisms that are being added to the wastewater stream. These additions of catalysts and microorganisms are meant to establish a more balanced flora or indigenous microbial growth in the system, to remove slime layers populated by anaerobic microorganisms and to remove decomposing organic waste material both of which cause or are caused by septic conditions from which hydrogen sulfide and other odorous compounds are generated. The use of bioremediation and/or bioaugmentation products can also deter the formation of grease and organic material build-ups before such build-ups can cause obstruction of the wastewater collection system. Results achieved by removing anaerobic slime layers, organic material and congealed grease, oils and soap build-up can be a reduction or elimination of both dissolved and gas phase hydrogen sulfide and other noxious odors, reduction or elimination of build-up of organic deposits resulting in faster wastewater flow through the piping, reduction or elimination of acidic corrosion of pipes, manholes, wet wells and equipment and cleaner wastewater with a higher level of dissolved oxygen. The results are a dramatic drop in noxious odors, reduced or eliminated buildup of organic deposits, cleaner wastewater with a higher level of dissolved oxygen, faster flow through pipes, and control of costly acidic corrosion due to hydrogen sulfide.
This approach, known as bioremediation, requires the introduction of microorganisms and bio-stimulators at a controlled rate into the waste water collection system. This has previously been done by spraying, pumping or otherwise delivering a liquid microbial solution into the collection system at various points such as wet wells and pumping stations. Liquid solutions, however, have a limited shelf life and require above ground storage as well as the availability of a power source, such as an electric outlet in the immediate vicinity of the solution-dispensing location. Additionally, not all microorganisms that are desirable in bioremediation can be prepared in a stable, liquid solution.
Dry bioremedial powders have been developed to greatly increase shelf life, and the variety of beneficial microorganisms that may be included in the treatment, however the use of these dry bioremedial powders in the field has been limited due to the lack of a dispensing apparatus capable of withstanding the high-humidity, corrosive atmosphere of the waste water collection system, and capable of keeping the powder dry to prevent caking and to assure reliable operation for extended periods of time without an external power source.
iv. Methods and Apparatus Previously Used for Delivering Chemical and/or Microbiological Treatments to Wastewater
In addition to manual distribution, various other methods and apparatus have heretofore been used for delivering liquid and dry biological or chemical treatments to wastewater at various locations in the wastewater collection/treatment system.
A. Peristaltic Pumps and Gravity Drip Systems for Adding Liquid Biological and Chemical Treatments
Liquid biological and enzyme products (e.g., Neozyme™ and Microbac™) useable for controlling grease build-up, as well as certain liquid bio-stimulants (e.g., Bioprime™, Neozyme™ and BioCatalytics™) that purportedly are useable for odor control, can be delivered into flowing wastewater streams at wet wells, lift stations or pumping stations. Peristaltic pumps typically require a separate source of electrical power and liquid preparations typically require above-ground storage, and thus are not suitable for use within a manhole at a remote site away from all electrical power sources. Gravity drip systems can be installed within man holes located at remote sites away from all electrical power sources but such locations typically do not include the above-ground storage facility required to house the li
Cooper Douglas C.
Mullennix Teddy E.
Barry Chester T.
Buyan Robert
Ennix Incorporated
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