Abstract: A process system is disclosed for the treatment of a waste sand material containing metal contaminants. The waste sand material is the product of sandblasting techniques used to remove paint. The metal contaminants generally include lead, copper, chromium, mercury and cadmium, among other heavy metals. The process particularly provides for the concentration of the lead contaminant in a waste sand that can be economically reclaimed or disposed in an environmentally safe manner. The process also produces a cleaned sand that contains only residual amounts of the metallic contaminants in environmentally acceptable levels. The process provides for the contacting of the waste sand material with a paint decomposer, attrition abrading this sand slurry, size separating the attrition abraded slurry to form a waste sand slurry and a cleaned sand, and removing a portion of the excess water content in the waste sand slurry.

Abstract: Solutions such as for example groundwater, drinking water, extracting solutions and effluents contaminated with metals, radioactive species and organics, singly or in combination, are treated by first removing undesirable oxidizing agents from the contaminated solution. Then the contaminated solution is separately treated with aqueous solutions of ferrous sulfate and hydroxide, which precipitate substantially all of the contaminants. Next, the precipitate is treated with a flocculant and/or a coagulant to form an easily dewaterable and separable solid. The solid contaminants are readily removed from the cleansed solution. The process utilizes a novel combination of steps which maximizes contaminant removal, minimizes waste volume, and produces a recyclable solution and a manageable waste stream. The preferred hydroxide solutions are sodium hydroxide, calcium hydroxide, and ammonium hydroxide.

Abstract: A solid NaCl or KCl electrolyte electrochemical concentration cell assembly (20) for measuring monitored gases (38) containing oxygen or a chlorine containing component is divided into two identical alkali ion conductive half cells (22) and (24) where each half cell has solid electrolyte (23) and (25) that consists essentially of NaCl, KCl, or their mixture and is secured to opposite surfaces of the closed end of a solid membrane (36) exhibiting sodium or potassium ion conductivity. The membrane (36) effectively isolates the monitored gases (38) contacting one half cell from a reference gas environment (40) contacting the other half cell.

Abstract: A solid electrolyte dual gas sensor (10) is made, containing a container body of a first solid electrolyte (11), in contact with a monitor electrode (17) exposed to a monitored gas environment (13) containing selected gas components to be measured and in contact with a reference electrode (15) which is additionally isolated from the monitored gas environment by a second solid electrolyte section (16), and optionally section (14), where the solid electrolyte section (16) is disposed within a ceramic oxide matrix material (25) where the matrix contains interconnected pores filled with electrolyte, and where the second solid electrolyte, at the operating temperature of the gas sensor, is effective to dissociate to provide the sole source of self-generated reference gases at the reference electrode (15).

Abstract: A solid electrolyte dual gas sensor 10 is made, containing a container body of a first solid electrolyte 11, in contact with a monitor electrode 17 exposed to a monitored gas environment 13 containing selected gas components to be measured, and in contact with a reference electrode 15 which is additionally isolated from the monitored gas environment by a second solid electrolyte 16, and optionally 14, where the second solid electrolyte, at the operating temperature of the gas sensor, is effective to dissociate to provide the sole source of self-generated gases at the reference electrode 15, corresponding to the selected gas components to be measured in the monitored gas environment, where, at the operating temperature of the sensor, the first solid electrolyte 11 is effective to conduct oxygen ions, and the second solid electrolyte 16 is effective to conduct ions selected from the group of sodium ions, potassium ions, and their mixtures.

Abstract: A solid electrolyte gas sensor 10 is made, containing a body of solid electrolyte 14, in contact with a monitor electrode 12 exposed to a monitored gas environment 13 containing selected gas components to be measured, and in contact with a reference electrode 15 which is isolated from the monitored gas environment, where the solid electrolyte at the operating temperature of the gas sensor is effective to dissociate to provide the sole source of a self-generated gas, at the reference electrode 15, corresponding to the selected gas component to be measured.

Abstract: In a solid electrolyte electrochemical cell device for generating an EMF signal based on the Nernst equation which is indicative of the SO.sub.2 content of a monitored gas environment, the oxygen content of the reference environment of the cell is adjusted to maintain it equal with the oxygen content of the monitored gas environment to eliminate the effect of oxygen on the EMF signal measurement of SO.sub.2.

Abstract: An alkali ion conductive solid electrolyte electrochemical concentration cell assembly for measuring gases containing anhydrides or related compounds in air or in oxygen-bearing gases is divided into two identical alkali ion conductive half cycles. Each half cell is secured to opposite surfaces of the closed end of a solid membrane exhibiting alkali ion conductivity corresponding to the alkali ion conductivity of the half cells. The membrane effectively isolates a monitored gas environment contacting one half cell from a reference gas environment contacting the other half cell while supporting the equilibrium mode of operation of the concentration cell assembly to generate an electrical signal indicative of a gas species of interest in the monitored gas environment.

Abstract: A circuit means in combination with a conventional oxygen ion conductive solid electrolyte cell establishes the cell in a voltage mode for the purposes of measuring excess oxygen and developing a voltage signal indicative thereof, and switching the cell to a current mode of operation in response to an excess combustible environment wherein current drawn by the cell to pump oxygen for combustible reaction with the excess combustibles environment is measured as an indication of the combustibles content of the gas.