Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
1999-10-12
2001-03-27
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
C210S716000, C210S724000, C210S903000
Reexamination Certificate
active
06207059
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to wastewater treatment and more particularly to a method for reducing the concentration of entrained solids, nitrogen, pathogens, and heavy metals; as well as killing bacteria, reducing the biological and chemical oxygen demands, reducing odors and generally improving the overall color and turbidity of the wastewater. In addition, the present invention relates to the chemical processing and decomposition of hydrocarbon compounds, and more particularly to a chemical composition and process for decomposing or encapsulating hydrocarbon based hazardous waste material.
BACKGROUND OF THE INVENTION
Wastewater treatment entails removing and treating many different types of pollutants or contaminants found in wastewater. There are, of course, many different types of processes that are aimed at treating wastewater to remove such contaminants and pollutants. Generally, the basic approaches revolve around biological and/or chemical treatment processes. While there has been significant progress made in developing new technology for treating wastewater, there still remains one serious concern that is especially felt by small towns and local governments all over the world. The thrust of the technology that has been developed today for treating wastewater is principally aimed at very large wastewater anaerobic and aerobic treatment facilities that require tremendous capital investment and space for retention compounds to facilitate digestion. These wastewater treatment systems and processes fall outside of the economic reach for many small local government bodies or small businesses that need or require their own wastewater treatment facilities. Therefore, there has been and continues to be a need for a cost effective wastewater treatment system that is affordable by small governmental bodies and others who have a need to treat and process wastewater. It is further recognized that some individuals need a system of a capacity or scale that is substantially below the size of the typical treatment plants normally designed for large municipalities.
Further, another deficiency of conventional wastewater treatment processes is that they often rely solely on aerobic or anaerobic digestion to remove contaminants and are not particularly designed to deal with a wide range of contaminants and pollutants typically found in wastewater streams. Therefore, there is also a need for a practical and cost-effective wastewater treatment process wherein the process effectively removes a wide range of pollutants and contaminants from the wastewater.
In addition, it is widely known that hydrocarbon based toxic and hazardous wastes are commonly produced as a consequence of numerous commercial and industrial processes. In some cases, this waste material may be difficult to contain at the point of generation, and as a result, this material may ultimately escape to the environment as a contaminant. Such contamination often poses serious environmental and health concerns, and consequently there arises the need to remove or neutralize this contamination.
One commonly employed process being used for treating low levels of hydrocarbon contamination is in situ bioaugmentation. In this process, genetically altered microorganisms are applied directly to the affected material where they proceed to digest the hydrocarbon contaminants. In the case of ground contamination, the effected soil is seeded with the micro-organisms and their digestion progress is continuously monitored. Although effective, treatments using this approach tend to be prolonged and may require extended treatment and monitoring periods, possibly lasting five to ten years before satisfactory results are obtained. Capital and operational costs for this process can be excessive.
Another common method of treating soil contaminated with hazardous hydrocarbon compounds involves the removal and off-site processing of the soil. The off-site processing typically includes baking the contaminated soil in a high temperature furnace or kiln so as to burn or combust the hydrocarbon contaminants and hence effectively remove them. This treatment approach, while not as slow as in situ bioaugmentation, tends to be extremely expensive as a consequence of the high transport and fuel costs associated with such processing. Soils treated via this process are often void of nutrients and beneficial bacteria, which negatively impacts soils reuse.
Still other equally expensive processes, which have been successfully employed to treat hydrocarbon-contaminated soil, involves in-situ exposure to highly oxidative reactants, such as hydrogen peroxide, in conjunction with lead and zinc bearing solutions. While effective in reducing the overall toxic hydrocarbon content of the contaminated soil, this type of treatment tends to attack or neutralize non-toxic organics which may also happen to be present in the soil. The use of strong oxidants can mobilize heavy metals if present in the soils and actually increase the danger to the public from them. In general, neutralization of non-toxic organics is undesirable and hence this approach is less than ideal in most instances.
Therefore, there is and continues to be a need for a practical and efficient technique for eliminating or neutralizing toxic hydrocarbon contaminants typically found in the environment which is fast acting, cost effective and which targets only the specific toxic hydrocarbons of concern.
SUMMARY OF THE INVENTION
The present invention relates to a chemical and mechanical method for treating municipal wastewater and basically entails chemical injection of a coagulant, a flocculent, and one or more oxidants to precipitate, flocculate, and separate solids and metals from suspension and solution within the wastewater. It further involves the reduction of pathogens by oxidation and elevated pH adjustments as well as the preparation of solids for disposal through vector attraction reduction by elevating the pH of the separated solids to 12 pH units. The process further involves removal of essentially all ammonia nitrogen via a combination of oxidation and ion exchange and subsequent chemical pH adjustment of the treated liquids to 8.5 pH units for discharge.
The process is dependent on a reagent comprised of mixing hydrated calcium hydroxide with bauxite and a carbon source to form the reagent. This reagent is directed into the wastewater stream and mixed with the wastewater therein and subsequently directed to a settling vessel for mechanical separation of the liquids and solids. It has been found that this reagent drives the pH of the wastewater to 12 pH units, causing the calcium carbonates and other metallic compounds within the wastewater/reagent solution to precipitate. As the solids settle within a retention vessel, the precipitating calcium products and settling bauxite create a coagulating effect with the entrained solids contained within the wastewater, causing the suspended solids to settle to the bottom of the retention vessel. This process causes the wastewater to be cleaned and purified of solids and metallic carbonate compounds, thus softening as well as cleansing the wastewater.
In addition, in one embodiment of the present process, it is contemplated that a flocculating agent in the form of a polymer can be added as an augmentation to the reagent just described. By introducing the polymer into the wastewater and mixing the polymer with the wastewater, flocs of the solids are formed and as the flocs accumulate and increase in size they tend to settle to the bottom of the reactor, thereby further cleaning or removing smaller particle solids from the wastewater.
Another option of the present invention deals with removing nitrogen compounds from the wastewater. Generally, nitrogen is reported as inorganic ammonia nitrogen as well as total Kjeldahl nitrogen (total organic and inorganic nitrogen). Other forms of nitrogen (inorganic) found in wastewater are nitrates and nitrites. The present invention entails raising the pH of the wastewater, removing the solids, and
Achemco, Inc.
Coats & Bennett PLLC
Lawrence Frank M.
Simmons David A.
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