Abstract: An apparatus for dewatering a pulp is described, comprising a vessel having a pulp chamber for pulp to be dewatered; a pulp inlet to the vessle; pulp outlet from the vessel; a filtrate chamber with an outlet for filtrate expelled from the pulp; a stationary cylindrical screen mounted within the vessel and defining said plup chamber and filtrate chamber on opposite sides thereof; and mechanical cleaning means supported by a shaft and disposed in the pulp chamber close to the screen face of the screen for removing a mat of pulp therefrom. The apparatus further comprises a backflushing means mounted outside the vessel and including a cylinder with first and second end portions and a piston mounted within the cylinder for reciprocal movement therein. The first end portion communicates with the interior of the apparatus, and the second end portion communicates with the filtrate chamber.

Abstract: A method for preventing stagnation and biofilm formation in the jet pump circuit of a spa, therapy pool or bath employing separate pumps or plumbing circuits for circulation and for pressure jet/massaging functions. The method includes a bidirectional water conduit through which water flows in one direction when the circulation pump is on, and in the other direction when the jet pump is on. All plumbing in the jet pump circuit is thereby kept free of biofilm by causing water containing a dissolved disinfectant to flow through it while the circulation pump is on. The invention further includes methods for automatically flushing the massage jet air lines and the air bubbler chamber with disinfectant-containing water while the circulation pump is on. This method increases the reliability and safety of spa disinfection, reduces the quantity of disinfectant needed, and in some cases enables ozone to be used as the major or sole disinfectant.

Abstract: Fats and proteins in wastewater are commonly concentrated in a dissolved air flotation cell as a sludge ("skimmings") which has a very high water content, even after centrifuging or the like. A process is provided to reduce the water content of the sludge thereby reducing the cost of disposal of the sludge.

Abstract: A method and apparatus are disclosed for efficient endothermic processing of liquids and the precipitation of dissolved elements and chemical compounds. Improvements over prior systems include system layout, components and modes of operation of the system. Applications of the system include destruction of toxic wastes and sewage treatment, precipitation of chemical compounds and elements including metals from solution (brine, sea water, industrial waste), sterilization and water purification, catalytic formation of chemical compounds, and processing of hydrocarbons.

Abstract: A method is provided for oxidizing arsenic in an arsenic-containing solution. The method comprises contacting the solution containing arsenic in a +3 oxidation state with an amount of a specific type of oxidizing agent, i.e., an agent containing at least one ##STR1## wherein X is a halogen to effect substantially complete oxidation of the arsenic to the +5 oxidation state. The amount of oxidizing agent used is substantially less than that which would theoretically be required. In accordance with a particularly preferred embodiment, the oxidized arsenic is reacted with a metal to form a substantially water-insoluble precipitate, preferably an iron or calcium arsenate.

Abstract: Methods for treating aqueous solutions and for recovering specific chemical products from an aqueous solution by ion exchange or adsorption by passing the aqueous solution through a regenerable filter bed comprising a flocculated mixture of finely divided active particulate material and filter aid materials having a depth of from about 3.0 inches to about 60 inches.

Abstract: Occluded acidity in particulate explosives is removed by slurrying the particles in an inert liquid and subjecting the slurry to wet-grinding. The inert liquid may include an alkaline salt at or near saturation. Separation of the ground explosive particles from the liquid phase results in a ground explosive material with much reduced acidity.

Abstract: Heavy metals are reclaimed from a concentrated wastewater solution containing heavy metal cations and an acid by adding to the wastewater a bed of scrap aluminum in a total amount between about 160% and about 180% of the stoichiometric requirement for complete reduction of the dissolved heavy metal cations to their elemental states and adjusting the acid content of the wastewater to 5% to 20% by volume and allowing the heavy metal cations to react with the scrap aluminum to oxidize the aluminum and to reduce the heavy metal cations to their elemental states thereby producing demetallized wastewater which is neutralized with caustic to produce a treated effluent.

Abstract: A device for controlling the flow of foam which uses a piston-cylinder arrangement to receive foam at the rapid flow rate of a foam generator until the cylinder is substantially full of foam and then to dispense the foam at a lower flow rate by using the piston to gradually push the foam out of the cylinder.

Abstract: A method or methods of controlling the growth of bacteria in the water of swimming pools and/or industrial water supplies by adding to the water a specified concentration of a stable divalent silver compound. The invention has the advantage over chlorination in that it is odorless and non-volatile. It furthermore is superior to monovalent silver compounds as these compounds do not decompose in the presence of light and resist precipitation by halides and form divalent soluble complexes which in the monovalent state are invariably insoluble solids.

Abstract: Cyanide present in aqueous streams, such as effluents from electroplating and gold mining operations is reduced or elliminated by contacting the cyanide-containing stream with oxygen and carbon dioxide in the presence of cupric ions. The oxygen may be provided by air or oxygen and the contacting is carried out at until the pH of the aqueous stream is reduced to a value in the range of about 6 to 8 and preferably 6.5 to 7.5. Cupric sulfate has been found to be particularly effective for the described reaction.

Abstract: A method for controlling zebra mussels in aqueous systems comprising treating aqueous systems which contain zebra mussels or which are prone to zebra mussel infestation with an effective amount of a water-soluble dialkyl diallyl quaternary ammonium polymer (polyquat). A preferred polymer is a poly(quaternary ammonium) compound having the recurring structure [DMDAAX.sup.- ] resulting from the polymerization of monomeric dimethyl diallyl ammonium X.sup.-, wherein X.sup.- is any suitable anion.

Abstract: Blow molded container and related process are provided wherein a container having at least an upper, non-self-supporting, flexible portion is blow molded to include an integral press-lock type closure about its upper open end. The blow mold cavity is formed to provide a rib or bead about one-half the periphery of the container open end, and a hollow recess about the other one-half of the periphery of the container open end. the upper end of the finished container may be flattened along its upper edge and closed by pressing the rib into the recess. It one embodiment of the invention, the lower portion of the container may be of greater thickness, but nevertheless integral with the upper portion, so as to be stable or self-supporting. In another embodiment, the container may be non-self-supporting throughout while, in still another embodiment, the container may be self-supporting throughout its length.

Abstract: A process for enhancing the filterability of organic pigments, which comprises adding to an aqueous pigment suspension 0.5 to 15% by weight, based on the pigment, of an unbranched aliphatic 1,2-dihydroxy compound containing 8 to 22 carbon atoms, and stirring the mixture for at least 15 minutes in the temperature range from 20.degree. to 100.degree. C.Pigments treated by the process of this invention have substantially enhanced filterability as compared with identical pigments which have not been treated with the 1,2-dihydroxy compound.

Abstract: A process for pathogen reduction in waste where dewatered sludge having a solids content in the range of 10-60% is mixed with an additive selected from the group consisting of calcium oxide or calcium carbonate group. Hydration to calcium hydroxide occurs with an attendant release of heat. The pH of the sludge is then elevated and the heat of the hydration reaction is retained resulting in effective neutralization of pathogens. Apparatus is also disclosed.

Abstract: Disclosed is a method and apparatus for preventing or minimizing scale deposition from hard water onto heat transfer surfaces in atmospheric cooling towers, such as those used in air conditioning and refrigeration systems, where evaporative cooling of water provides the necessary heat sink to the atmosphere. An electrical/mechanical control system responsive to changes in density of the water in the evaporative cooling system operates to permit discharge of water containing dissolved and suspended solids from the system when its density reaches a predetermined maximum value and to discontinue the discharge of cooling system water when its density reaches a predetermined minimum value. Water drained from the cooling system is replaced by fresh water, preferably by water containing chemical additives to increase solubility of hard water minerals in the cooling water.

Abstract: A method for assaying compounds belonging to the group biogenic amines and including catecholamines, indoleamines, their metabolites and derivatives, and other small molecular weight compounds using a boric acid extraction method followed by high pressure liquid chromatographic separation in conjunction with electrochemical detection. The method utilizes high purity chemical and liquid components, a microparticulate-silica bonded phenyl stationary phase in the chromatography column and special cleaning and maintenance measures for the various components of the assaying apparatus which result in reduced baseline noise and allow the electrochemical cell to be operated at a sensitivity of one nanoamp or less full scale deflection on a continuous basis.

Abstract: A universal swimming pool water filter apparatus for a bottom opening tank comprising multiply useful dual reverse flow port means and cooperating filter medium support having various filtered water passing openings arranged to accommodate fixed cloth or free particulate filtering media, the port means flow being varied with the type of filtering medium support so that a minimum of different production parts are needed to meet all filtering needs, with a consequent reduction in manufacturing equipment and parts inventory.

Abstract: The dewaterability of alum sludge is improved by treating the alum sludge with low doses of hydrogen peroxide. The hydrogen peroxide enhances filterability and drainability of the alum sludge and also improves the resulting cake quality of the dewatered alum sludge.

Abstract: Procedure for draining of sludge, especially flocculent flotation sludge, including introducing water-sludge mixture into a settling tank with an overflow and removing the settled sludge layer from the settling tank with a slanted conveyor. Horizontal grooves are then pressed in the sludge layer by section roller rows arranged over the slanted conveyor belt. The water extracted from the sludge layer is collected and canalized in these horizontal grooves. The back-flowing water is then collected and guided off in water drainage systems arranged over the slanted conveyor. These water drainage systems are tilted toward and enter a front side of the horizontal grooves. This collected water may either be eliminated directly or returned to the settling tank.