Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Reexamination Certificate
1998-02-24
2001-09-25
Gorgos, Kathryn (Department: 1741)
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
Reexamination Certificate
active
06294057
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to enhanced inversion, dispersion and activation systems and devices. More particularly, the present invention relates to enhanced organic polyelectrolytes (polymers) and organic polyelectrolyte solution inversion, dispersion and activation using electrohydraulic discharge energy delivered into the polymer or polymer solution. The present invention is applicable to situations in which an organic chemical, polymer or enzyme must be disentangled or uncoiled to obtain optimum performance. As a result, less polymer and less energy in activating the polymer are used when the polymer or polymer solution is optimally activated, reducing costs and improving efficiency.
Polymers have been widely used in sludge (biosolid) conditioning applications, such as dewatering applications where fine solid particles are removed from biosolids. Polymers are also used extensively in water treatment, wastewater treatment and industrial water treatment. They are also widely used in the food and chemical industries.
In general, polymers are organic macro-molecules composed as chains of five or more individual monomer building blocks linked together in a linear or branched configuration. Various functional groups may be located along the chain. Such functional groups provide charged sites which may be used to neutralize electrical charges on colloidal particles. The functional groups along the chain may possess a negative charge (anionic polymer), positive charge (cationic polymer), or an overall neutral charge (nonionic polymer).
Polymers are typically available in dry form, liquid solutions, and inverse emulsions. These “neat” preparations are diluted in water, mixed into solution and activated by an inversion process of mixing and aging to achieve increased activity. The purpose of the activation process is to allow the coils of the polymer to loosen and unwind, increasing the exposure of the functional charge sites to increase the effectiveness and performance of the polymer. During the aging process, the diluted polymer solution is allowed to sit in a tank with gentle or no stirring. In sludge dewatering applications, for example, when a polymer is optimally activated by exposing more of its functional groups, less polymer is required and higher cake solids are obtained. This results in lower operational cost and better performance.
For ease of understanding, the present invention, as well as most of the background of the invention, will be discussed by reference to the dewatering of biosolids. It will be understood, however, that the inventions may be employed in a wide variety of applications and technologies, including but not limited to water, wastewater and industrial water treatment as well as in the food, chemical and petrochemical industries.
In the past, and in most current biosolid dewatering applications, activation of polymers is accomplished by equipment specified by design engineers. In many instances, specific polymer preparation requirements are not met because of misinformation or misunderstanding between equipment designers, consultants and contractors. These facilities usually include pumps and calibration devices which allow a specified dilution of the polymer and water. This solution is then transferred to a mixing and aging tank where the polymer solution is activated. Polymer mixing and aging facilities are not usually designed to accommodate any particular type of polymer.
FIGS. 1A and 1B
schematically show a variety of systems typically used to activate polymer. These methods require, among other things, expensive equipment with high maintenance costs. Moreover, optimizing the equipment for a particular polymer is usually difficult and requires expensive modifications as well as constant attention and adjustment. Thus, in most cases, polymer activation is not optimal.
In biosolid dewatering applications, for example, it is first necessary to determine the type and amount of polymer to achieve the required conditioning, making it necessary to calculate such parameters as the solution strength, usage and feed rate for each operation (see e.g.,
Chemicals Used for Dewatering,
Ch. 13, pp. 254-57). In such applications, water-soluable polymers are typically used, such as: methyl cellulose, carboxyl methyl cellulose and cellulose ethers; starches (ethers and acetates); polyvinyl alcohol (PVA), ethylene oxide polymers, polyvinyl pyrollidione, polyethyleneimine; as well as others. The dewatering calculations are complicated because of the continually changing composition of the biosolids and the fact that polymers in solution are only active and effective for certain finite periods of time. In practice, once the solution strength, usage and feed rates are calculated, the values are sometimes doubled to provide for a margin of error. This necessarily results in increased polymer usage and energy costs.
Static, in-line mixing technology to mix and activate polymers has been studied. The technology is appropriate for certain polymers only and suffers from, among other things, clogging problems. In the early 1980s, for example, in-line blending systems were developed that led to enhanced polymer activation. These systems are still in use today, particularly in the biosolid dewatering field; for example, to activate polymer solutions prior to or after being mixed with the biosolids to be treated. In many instances, these systems actually cause decreased performance in polymer activation because no means for aging the polymer is provided and/or the fragile polymer is over-mixed.
One such currently available method and apparatus is described in U.S. Pat. No. 5,164,429 to Brazelton et al., which is typical of the present state of polymer activation. In this type of system, polymers are activated by some form of rotating mixing mechanism to impart mechanical energy into the polymer solution and cause activation of the charge sites. Polymers are mixed in their diluted solution and further activated by mixing in separate and distinct zones of the mechanisms. Other systems use in-line mixing devices, or a combination of the two.
The claims of these devices is that the polymer solution is activated sooner than if the solution were traditionally mixed and allowed to age. However, none of the systems are able to change the physical or chemical characteristics of the polymer solution needed for activation. Another presently popular in-line mixer-type of system is available as the Polymaster of Komax Systems, Inc., Wilmington, Calif. Still other examples of polymer dilution/activation systems and devices are described in U.S. Pat. Nos. 5,284,627 and 5,252,635, both to Brazelton, et al.
A novel technology still in its infancy is the use of pulsed-plasma discharges (“pulsed power”) in aqueous solutions to treat water and wastewater. High energy underwater discharges can induce a number of physical and chemical effects on solids and chemical compounds dissolved and suspended in water. Depending upon the energy of the pulse and the frequency of the pulses, these effects include the formation of high temperature, high pressure plasma, shock waves and electromagnetic radiation, including UV and X-rays.
Pulsed power technology, as currently employed, generally employs high frequency pulses (generally greater than one pulse per second) of electrical energy, typically of a millisecond's duration, to solids or organisms in a liquid which is between two electrodes. The pulsed power technology currently employed also typically require relatively high energy level pulses (of approximately 1,500 joules/second). One of the earlier devices for generating pulsed power, commonly referred to as a pulsar, is shown and described in U.S. Pat. No. 3,220,873 to R. H. Wesley, for applications such as the removal of constituents from solutions as precipitates and impregnation of surfaces with desired substances.
Some, including R. H. Wesley, have attempted to apply pulsed power technology directly to the treatment of wastewater. For example, U.S. Pat. No. 4
Freeman Dylan J.
Wachinski Anthony M.
Gorgos Kathryn
Maisano J.
Niro Scavone Haller & Niro
Thames Water Utilities
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