Abstract: A water treatment system provides a flow of treated water having a pre-established quality, for example, a maximum TDS and permitted pH range, from a flow of reclaimed water having a quality poorer than the pre-established quality of the treated water and a flow of treatment water. The system includes a mixing reservoir; first and second fluid conduits connected to the mixing reservoir for flowing the reclaimed water and the treatment water into the reservoir; and a third fluid conduit connected to the mixing reservoir for discharging a flow of treated water from the mixing reservoir; and sensors connected for sensing the flow rates and qualities of the reclaimed water and treatment water flowed into the mixing reservoir and of the treated water discharged from the mixing reservoir.

Abstract: The amount of electrical power delivered to a dialysate heater in the dialysis machine is maximized without substantially exceeding a predetermined maximum allowed power consumption for the dialysis machine. The instantaneous power consumed by the machine is measured and compared to the maximum allowed power consumption. The excess of power beyond the instantaneous power consumed up to the maximum allowed power consumption is then made available to the heater. The worst case power consumption limitations of the dialysis machine components do not adversely affect the heat available from the heater. The rate at which dialysis treatments may progress may increase or the time required for dialysis treatments may decrease.

Abstract: A method of regulating aeration in biological treatment of wastewater by implementing a step of eliminating carbon in aerobiosis, a step of nitrification in aerobiosis, and a step of denitrification in an anoxia, in which method the oxidation-reduction potential is continuously measured in a treatment system, a curve is established of variation in oxidation-reduction potential as a function of time, and the derivative thereof is calculated, wherein, when the derivative tends towards zero, the derivative and the value of the oxidation-reduction potential are correlated to determine whether aeration should be started, continued, or stopped.

Abstract: The present invention provides a sensor (10) and method for detecting the presence of water or glycol in an oil system. The water/glycol sensor includes a water/glycol concentrator (12) which concentrates the water and glycol in a concentrating zone (84). A water/glycol detection probe (14) is located in the concentration zone (84) such that minute quantities of water or glycol in the system may be detected.

Abstract: The present invention provides an apparatus for separating into solid material and liquid a mixture thereof. The apparatus includes a movable filtering element for filtering the mixture, a feed device for supplying the mixture onto the filtering element, a suction device for drawing off liquid from the mixture through the filtering element and a measuring device for measuring the area or areas on the filtering element where the liquid is predominantly to be found.

Abstract: A method for controlling the detoxification of aqueous solutions containing cyanides and/or cyano complexes, in particular zinc cyano complexes, with the use of a source for formaldehyde for glycolnitrile formation and a source for hydrogen peroxide for perhydrolysis of the glycolnitrile is disclosed. During the addition of the source for formaldehyde at a pH value in the range from 8.5 to 12 the pH value is kept constant by addition of an acid. The addition of the source for formaldehyde is discontinued if the pH value no longer increases.

Abstract: A self-contained, self-sufficient system and method for purifying non-potable water to make the water potable is disclosed. The system comprises (a) means for oxidizing which treats the non-potable water by oxidizing organic substances, disinfecting the non-potable water by destroying parasites, bacteria and viruses, and causing coagulation of colloids, (b) means for filtering the treated non-potable water wherein oxidized organic substances, destroyed parasites, bacteria and viruses, and colloids are removed to provide potable water, and (c) means for optionally generating a biocide from dissolved salts when dissolved salts are present in the non-potable water. The system can also include means for contacting potable water generated by the system with a biocide. The system is self-contained and self-sufficient, requiring no external resources for the continuous operation thereof.

Abstract: A metallic indicator electrode senses the anionic charge per unit time borne by the dispersed phase of a stream of an aqueous dispersion of negatively charged particles by virtue of the potential developed by the electrode as measured by a voltmeter. The developed potential can be used downstream, for example, to control the addition of a water treatment chemical or extraction of water from the stream.

Abstract: A system and method are disclosed for controlling the amount of cationic coagulant to be introduced into a laundry waste water having a content of non-solid fats, oils and/or grease (FOG) which is to be reduced.

Abstract: A control system for a water softener, control device therefor and methods of making the same are provided, the system comprising a microcontroller operatively interconnected to an output of a comparator to effect a subsequent operation of a recycling unit for the water softener when the output signal is at a certain condition thereof, the system causing the output signal to have a phase shift relative to the phase of an A.C. power supply of the system when a sensing electrode unit in the ion exchange bed of the water softener is at a certain resistance value relative to the resistance value of a reference electrode unit that is also disposed in the ion exchange bed, the phase shift comprising the certain condition of the output signal, the microcontroller determining the certain condition by comparing the phase of the output signal to the certain phase.

Abstract: A method for controlling the chemical treatment of a solution comprises the steps of feeding a treatment chemical into the solution, applying an external voltage across a reference electrode and a working electrode of a voltammetric sensor while the electrodes are immersed in the solution, measuring a current that flows through the working electrode, converting the measured current into a feedback signal indicative of the concentration of treatment chemical in the solution, and using the feedback signal to control the rate of feeding the treatment chemical.

Abstract: An automatic system to precisely maintain bactericidal action in a reservoir of water equipped with a recirculation system, such as a swimming pool, decorative fountain, spa, cooling water reservoir or the like. The automatic system includes: a service loop which bypasses a portion of the recirculating water past sensors which measure the pH and oxygen reduction potential (ORP) of the water and in which acid and halogen are injected by a chemical feed unit; an electronics unit for determining the injection quantity of the acid and/or halogen needed to restore pH and ORP to stored set-points, and for controlling the chemical feed unit in response to the injection time determination; and an optional telecommunication unit for reporting process control status to a remote location and allowing modification of the process parameters, selection of operating modes, and performance of diagnostic tests from the remote location.

Abstract: The sample separator including a first suction nozzle, serving also as an electrode, for extracting one of first and second components each having an impedance different from each other, a second suction nozzle, serving also as an electrode, for extracting the other component, a nozzle driving member for ascending/descending the nozzles as one unit, and an interface detecting member for detecting an interface between two components. The interface detecting member further including an impedance detector for detecting an impedance between the two nozzles serving also as the electrodes, a storing section for storing a first threshold value to detect the first component, and an operation control member for comparing the first threshold value stored in the storing member with a detected value obtained by the impedance detector, and for controlling the nozzle driving member based on a result of the comparison.

Abstract: A wastewater treatment system and method for chemical precipitation and removal of metals from wastewater in a continuous or batch treatment process includes an ion-selective sulfide electrode and a reference electrode disposed in a precipitation tank for measuring an electrochemical potential therebetween in a predetermined range. A controller unit is provided which is responsive to the electrochemical potential in the predetermined range and is connected to a precipitant feed unit for automatically controlling the chemical precipitant fed into the precipitation tank.

Abstract: The feature of the present invention resides in that when a polyelectrolyte coagulant is added to sludge to dewater the sludge in a sewage treatment plant, the dosage level of the polyelectrolyte coagulant to be to the sludge is controlled most properly, whereby moisture content of dewatered cake can be minimized.

Abstract: Aerated bitumen froth containing bitumen, water, air and solids is the product of the hot water extraction process for recovering bitumen from oil sand. Measurements related to the water content of the froth can be obtained by measuring its resonant frequency in a calibrated output, open-ended microwave cavity. By also measuring the bulk density of the froth and assuming a constant relationship for the solids content, one can compute from the assembled data the output quality of the froth. The measurements can be taken repetitively at the vessel as the froth is produced and used to almost instantly provide froth quality information.

Abstract: A treatment method for removing arsenic from water includes conditioning the water with one more additives including an iron salt, an acid, and an oxidant until the water contains more ion than arsenic, is acidic, and has an ORP of about plus 600 mV. A reagent is then added to the conditioned water until it becomes basic and the water and additives are then reacted in a reaction chamber wherein iron and arsenic are co-precipitated in the form of iron arsenate and iron hydroxide or iron oxide. Treated water is then separated from the precipitate by settling of filtering.

Abstract: A method is disclosed for the treatment of water, containing an oxidizing agent, flowing through a conduit or contained in a vessel. The oxidation reduction potential or the ORP of the water is continuously measured at a sensing position and a reducing agent is fed to the water in response to the measured ORP to neutralize the oxidizing agent and maintain a desired concentration of reducing agent residuals in the water at the second sensing position.

Abstract: An automatic control system for maintaining the quality of water in a cooling tower utilizes a probe (38) which senses the oxygen reduction potential (ORP) of a soap having a 1:1 stoichiometric equivalent of mineral acid and ammonia or amine in the water. The soap is pumped from a chemical supply means (20) containing the soap in response to the ORP of the soap in the water falling below a predetermined threshold. A second sensing probe measures the conductivity (in MHos) of the water as a factor of the total dissolved solids (TDS) to control the bleed-off or blow-down of the water. The chemicals, which are supplied for maintaining the ORP, permit significantly higher total dissolved solids in the water than with standard cooling tower systems, without the buildup of scale. As a consequence, water consumption is significantly reduced; and the system functions automatically, without requiring periodic visual inspection, water analysis or manual operation.

Abstract: A method and apparatus for automatically measuring the acidity of overhead water in an oil refinery, and dispensing a neutralizing agent into the refinery system at a rate responsive to that measurement. A sample of overhead water is collected and passed through a filter and cation exchange resin. The acid concentration of the sample is then automatically measured and a signal generated based on the concentration. The signal goes to a controller which controls the dispensation rate of neutralizing agent into the refinery system, thus reducing the acidity of the overhead water and limiting the corrosive effects of such acidity.

Abstract: To analyze the oxidizable substances, for example the chemical oxygen demand (COD), contained in an aqueous sample liquid, for example sewage water, the aqueous sample liquid is diluted with dilution water and fed into a reaction container where it is mixed with ozone from an ozone generating device. After passing through a second reaction container, for example a tubular reactor, the sample liquid reaches an ozonometer appliance. Ozone being added continuously, the ratio of sample liquid to dilution water of the mixture is regulated in such a manner that the residual ozone content measured by the ozonometer appliance remains constant at a predetermined level. The ratio of sample liquid to dilution water of the mixture required to maintain the reading on the ozonometer at the predetermined level is used to determine oxidizable substances contained in the water, in particular COD.

Abstract: Reduction of the nitrite content of aqueous solutions by treatment with hydrogen peroxide in the acidic pH range can be controlled by measurement of the redox potential. Contrary to the teaching of the prior art, addition of the hydrogen peroxide in the process according to the invention is terminated not at the highest redox potential, but only after lowering of the potential to a value of 650.+-.10 mV. In this way, nitrite contents below 1 mg/l can be obtained even when the solutions additionally contain fluctuating amounts of various compounds oxidizable by H.sub.2 O.sub.2.

Abstract: In an intermittent aeration activated sludge process in which aeration and agitation is repeated alternately, a first aeration tank and a second aeration tank are connected to each other and an ORP meter is applied to each tank. In the first aeration tank, the sum of an aeration period and a denitrification period of an agitation step is controlled to a predetermined period T.sub.gs based on a time when a bending point appeared on an ORP curve in a previous cycle. In the second aeration tank, the sum of an aeration period and an agitation period is controlled to a predetermined period T.sub.ds longer than T.sub.gs based on a time when an ORP measured value reached a predetermined value in a previous cycle. Operations of the first and second aeration tanks are simultaneously transferred from the agitation to the aeration based on detection of the predetermined ORP value. As a result, a necessary anaerobic condition period is secured in the first aeration tank.

Abstract: A continuous process by which waste water containing low to high concentrations of organic constituents and total nitrogen is biologically purified to such an extent that the organic constituents are minimized, the content of total nitrogen is completely nitrified, if it exceeds the assimilation demand, and the nitrate formed is reduced by aerating the waste water or exposing it to oxygen while not exceeding a preselected redox potential. In the subject process, the expenditure on the oxygen introduction and the expenditure on the denitrification are minimized. Further, the amount of excess sludge produced is extremely small.

Abstract: A system and method for detecting the presence of contaminants in supercritical fluid. The system is based upon the use of an absorbent module comprising an absorbent which selectively absorbs the contaminant being measured and wherein the electrical properties (i.e. conductance and/or capacitance) of the absorbent varies depending upon the amount of contaminant absorbed. A sample stream of the supercritical fluid is contacted with the absorbent material. By measuring the electrical properties of the absorbent, contaminant levels are measured and monitored.

Abstract: Method of processing water including bath water and water employed in air treatment plants, which is conveyed in a circuit containing a contaminating point and a processing plant, the water exiting the contaminating point being contaminated water having a redox potential which is measurable and the method including, in the order recited, continuously measuring the redox potential of the contaminated water at the inlet of the processing plant; introducing into the contaminated water an auxiliary processing agent which is a mixture including a flocculating agent which promotes deposition of corpuscular pollutants and a halide which reduces ozone and disinfects the contaminated water as a function of the redox potential in such a way that the auxiliary processing agent is introduced in proportion to a drop in the redox potential; treating the water with ozone from an ozone generator in a spatial region defined within the processing plant and forming flocks including the corpuscular pollutants; and filtering the

Abstract: A system is disclosed for controlling the amount of treatment composition, e.g., cationic coagulant, to be introduced into an aqueous medium, e.g., a laundry waste water, having a content of non-solid fats, oils and/or grease (FOG) which is to be reduced. This system comprises a detector adapted to determine the electric charge value of a material comprising the aqueous medium having a FOG which is to be reduced and to provide a signal indicative of this electric charge value and an automatic processor provided with a relationship of the amount of treatment composition to be introduced into the aqueous medium to reduce the FOG of the aqueous medium to a given level as a function of the signal, and adapted to receive the signal and to provide a control signal to a source of treatment composition to control the amount of treatment composition introduced from the source of treatment composition into the aqueous medium.

Abstract: A water treatment apparatus has a tank that contains a resin bed through which water flows. The apparatus is controlled by occasionally measuring the conductivity of the resin bed at two spaced apart locations to produce first and second conductivity measurements. The ratio of the two conductivity measurements is calculated periodically. The present ratio value, along with the minimum and maximum ratio values that occurred since a previous regeneration of the resin bed, are used to determine the movement of an exhaustion front through the resin bed. A probability of exhaustion also is determined and when that probability exceeds a given value, regeneration of the resin bed is initiated. The conductivity measurements are used to determine if the resin bed has lost efficiency and in which event a warning signal is sent to the user.

Abstract: A method and apparatus for the removal of water, liquids and liquors from sludges and slurries, the sludges and slurries mixed with an electrolyte to improve conductivity and introduced into a conveyor chamber where an electrical path is established to permit electrical energy to pass through the conveyor chamber and the sludge, slurry and electrolyte to free bound water and remove it from the sludge or slurry, and to heat the sludge or slurry to drive off remaining water by vaporization.

Abstract: A process is disclosed for the detoxification of aqueous solutions containing cyanides and/or cyano complexes in the presence of heavy metals which are Mn, Co, Ni, Cu, Cd and Zn, more particularly Cu, by oxidative treatment of the solutions with peroxide compounds at pH values of 8 to 12. Peroxide compounds from the group consisting of alkali metal percarbonates and alkaline earth metal peroxides are used. The peroxide compounds are added to the solutions to be detoxified per se or are formed in situ therein from hydrogen peroxide and other components. Sodium perborate, sodium percarbonate and calcium peroxide are preferred.

Abstract: A device for detecting and monitoring the charge condition of finely divided solid charged particles in a fluid-flow is so devised as to accept the continuous and full volumetric flow of the fluid and to automatically and repeatedly sample and measure the charge condition. The full flow is accommodated without restriction in a passageway which intersects a bore wherein a streaming current detector (SCD), located below the passageway, is caused to cyclically sample and measure the charged-particle content of the flow; and at a passageway location downstream from the point point of cyclical sampling a head-creating formation assures that the fluid level will be raised to maintain a filled condition of the sampling bore. The device is further illustratively disclosed in use in a fluid-treatment system, wherein the SCD produces a signal to control flocculant added to the full flow of the fluid.

Abstract: A method for treating and resolving a phosphorus containing oily waste emulsion is described. The treatment uses an emulsion destabilizing cationic polymer of low molecular weight in combination with filter aids to form a coacervate slurry. The coacervate slurry can be optionally treated with either high molecular weight anionic or cationic coagulents, or combination thereof. The suspended solids formed by the above treatments are removed from the slurries and wasted or discarded or incinerated. The remaining liquids may be recycled, reused, or treated as effluent meeting environmental standards.

Abstract: The optimum antifoulant concentration and cleaning interval for reverse osmosis membranes is determined by providing samples of a liquid to be purified in a reverse osmosis system, the samples having a range of antifoulant concentrations added. The zeta potential for each sample is measured, and the amount of antifoulant that provides the lowest (most negative) zeta potential is selected as the preferred antifoulant concentration. A cleaning frequency sample of the liquid to be purified with the preferred antifoulant concentration is prepared and passed across a cleaning frequency membrane that passes dissolved matter in the permeate but does not pass colloidal material. The rate of change in flow of the permeate of the cleaning frequency sample is measured as a function of time, and the cleaning frequency of the cleaning frequency sample is determined.

Abstract: Optimum amounts of demulsifiers for breaking oil-in-water emulsions with low salt contents and high surfactant contents are determined by measuring the streaming potential in the emulsion to be broken.

Abstract: A sensor for the detection of wood chip level in a digester, for example, a Kamyr digester, which consists of: (a) a probe, several meters long, vertically mounted inside the top part of the digester; (b) a series of bare metal electrodes in the side of the probe, spaced typically a few centimeters apart, and electrically insulated from the probe wall; (c) electronic circuit processing to allow any pair of electrodes to be selected, and (c) a means to allow the electrical properties of a liquor or wood chip and liquor mixture between the electrodes of a pair to be measured, and the level deduced from the measurement.

Abstract: Monitoring and controlling the reactivation of an alkanolamine solution containing heat-stable salts of such alkanolamine with stronger acid anions and weaker acid anions by contacting the alkanolamine solution (a) with a strong base anion exchange resin which has a high affinity for stronger acid anions (b) contacting the effluent alkanolamine solution from the strong base anion exchange resin with a second strong base anion exchange resin which has an affinity for weaker acid anions (c) measuring and recording the electrical conductance of the effluent solution from the first mentioned anion exchange resin (d) removing the first mentioned anion exchange resin from service when the conductance of the effluent alkanolamine solution from said resin indicates breakthrough of stronger acid anions in said effluent, (e) measuring and recording the electrical conductance of the effluent alkanolamine solution from the second mentioned anion exchange resin (f) removing the second mentioned anion exchange resin from s

Abstract: A system is disclosed for controlling the amount of treatment composition, e.g., cationic coagulant, to be introduced into an aqueous medium, e.g., a laundry waste water, having a content of fats, oils and/or grease (FOG) which is to be reduced. This system comprises a plurality of detectors each of which is adapted to determine a parameter, other than the FOG level, of a material comprising the components of the aqueous medium and to provide a determined signal indicative of the determined parameter; and an automatic processor provided with a relationship of the amount of treatment composition to be introduced into the aqueous medium to reduce the FOG of the aqueous medium to a given level as a function of the plurality of determined signals, and adapted to receive the plurality of determined signals and to provide a control signal to a source of treatment composition to control the amount of treatment composition introduced from the source of treatment composition into the aqueous medium.

Abstract: Apparatus for measuring the concentration of carbon compounds in water, the apparatus including a reaction zone for converting such carbon compounds to free and/or combined carbonaceous acids, a device for introducing at least a portion of the water to be analyzed as liquid or vapor into such zone, a device for contacting such acids with weakly basic anion exchange resin and a device for measuring the electrical impedance of at least a portion of such resin.

Abstract: A beltpress controller performs on-line measurements of output sludge cake thickness. A controller takes a product of the measured cake thickness with belt speed, moisture content and belt width to determine a rate of dry solid output per unit time. The calculated rate is compared with a desired rate and the sludge flow rate is adjusted by adjusting the speed of a sludge feed pump to obtain the desired dry solid output rate. In systems which mix polymer with the sludge to increase the dewatering efficiency, the sizing of a mixing orifice through which the sludge and polymer is provided is adjusted to maintain a substantially constant mixing energy. This prevents errors in the streaming current detector which measures the amount of excess polymer in the filtrate and the controller adjusts the speed of a polymer dosing pump accordingly.

Abstract: A method and apparatus for polishing a condensate is provided wherein the condensate contains both suspended and colloidally dispersed solid impurities, and also intermittent and variable levels of ionic impurities and dissolved silica. When the ionic impurities exceed a preselected level, a finely divided ion exchange resin mixture is first admixed with the condensate at a rate sufficient to reduce the level of such impurities to a preselected level within a preselected contact time period. Thereafter, the resulting condensate is passed through a membrane filtration device to remove such suspended and dispersed solid impurities. A simple, effective and reliable retrofittable apparatus adapted for use with BWR's fitted with precoat filter systems is provided.

Abstract: This invention relates to a method for the in-vivo determination of hemodialysis parameters. To carry out hemodialysis with the greatest efficiency and safety, it is inter alia necessary to know the clearance of the dialyzer. To be able to determine the same in vivo, the invention provides a method in which the electrolyte transfer of the dialysis fluid is measured by means of a measuring device at two different predetermined dialysis fluid ion concentrations and the dialysance is determined on the basis thereof, which dialysance is numerically equal to the clearance.

Abstract: A method of operating a drum centrifuge having a foraminous drum rotatable about an axis it is centered on comprises first filling a charge of a suspension into the drum while rotating it about its axis so that the charge forms an annular stratified body having an inner surface and the liquid phase of the body passes radially outward and leaves behind the solid phase as a filter cake and then refilling at least one additional charge of a suspension into the drum onto the filter cake while rotating the drum as in the preceding filling step to add the solid phase of the additional charge to the cake already in the drum. Then at least periodically the radial position of the inner surface of the body in the drum is detected and the dry point when the liquid phase has substantially passed radially out of the drum is ascertained to generate outputs corresponding to the detected radial positions and the times same are detected.

Abstract: The content of halo-organic pollutants in water is lowered to residual AOX values below 1 mg/l, preferably below 0.1 mg/l by adjusting the Fe.sup.2+ comtent of the water to 20 to 1000 mg/l, adding a precipitated or pyrogenic silicic acid, converting 20 to 1000 mg of the Fe.sup.2+ into Fe.sup.3+ by adding in an oxidation agent, preferably hydrogen peroxide, and separating the iron (III) hydroxy complexes formed and the silicic acid, which contain the halo-organic pollutants in an adsorbed state, at pH 5-10. The method can be controlled in a simple manner as regards the addition of Fe.sup.2+ and oxidation agent via the Fe.sup.2+ /Fe.sup.3+ redox potential.

Abstract: A process and an apparatus are disclosed for the monitoring and treatment of circulating water of open circulation systems, preferably in cooling tower circulation systems, in which at least one partial minor stream is continuously diverted from the main circulating water supply and directed through a compact module in which, in an automatic sequence, the pH value of the partial stream is measured and adjusted by the addition of any necessary acid, the conductivity of the partial stream is measured, preferably inductively, and an elutriation unit is activated to drain excessively conductive water, corrosion inhibitor is added to the partial stream in dependence upon the quantity of fresh water added to the circulating water, organic and/or inorganic biocides can be added and the partial stream is filtered and returned continuously to the main circulating water supply.

Abstract: A method and apparatus for controlling a fluid treatment apparatus that includes a resin tank containing an ion exchange media. A control valve controls the regeneration cycle and includes a regeneration control turbine operatively connected to a regeneration control disk forming part of a servo system. During regeneration, a meter flow of fluid emitted by a regeneration control nozzle produces rotation in the turbine to effect a regeneration sequence. Regeneration is initiated by a regeneration initiating nozzle which emits a stream of fluid at the turbine for a predetermined time interval in order to initiate a regeneration cycle. A control system includes a sensor for monitoring the fluid quality level of the source fluid or the treated fluid and initiates regeneration. When the control system is used with the disclosed control valve, the control system communicates presssurized fluid to the regeneration initiating nozzle upon sensing a predetermined quality level.

Abstract: A vessel is provided with a flexible plastic tube containing an electrical contact switch. Impure water is added to the vessel between the tube and the wall of the vessel. The vessel is then placed in a home freezer. Upon partial freezing of the impure water, the ice expands to flex or compress the tube to close the switch so as to actuate a detector or alarm. The user then removes the unfrozen water, and allows a fraction of the ice to melt. The just formed water is checked for purity by a conductivity measurement. If impure, the water is removed, and the ice is allowed to further melt until the desired purity level is reached at which time the remaining ice is melted to obtain purified water. The device and method are particularly suitable for home use to economically obtain purified water.

Abstract: A method and apparatus for dewatering material, the material having a certain degree of conductivity, the material being introduced into a pressure chamber and simultaneously being compressed as electrical energy is introduced into the material elevating the temperature and driving off the fluid or water in the form of steam through apertures in the pressure chamber, the residence time being a function of the conductivity of the material, the dimensions of the pressure chamber and the electrical energy and pressure directed on the material.

Abstract: There is disclosed a method for the protection of metal surfaces against corrosion by the formation of a passivating coating of zinc silicate on the surfaces of the metals exposed to the water. The metal surfaces are preconditioned by contact with water containing a soluble zinc salt in an amount from about 0.5 to about 5 parts zinc per million weight parts of the water while the total alkalinity is maintained above 100 millequivalents by the addition of a water soluble alkaline material, as needed. The pretreatment passivates the metal surfaces with a coating of zinc carbonate, as can be determined by measuring the magnitude of external current flow between electrodes of a test probe maintained in the water.

Abstract: A steam boiler having a water blow down in which the blowdown rate is automatically controlled in response to the flow rate and impurity level of the make up water so as to maintain the boiler water impurity level below a specified concentrations.

Abstract: A filter centrifuge has a feeler arm which contacts the free surface of the centrifuge contents to signify by the angular displacement of the arm, the thickness of the layer of contents in the filter drum. On the contact surface of the filter arm, at least one sensor is provided which is responsive to a characteristic of the material constructed by the arm for signalling the nature of the material.