The water treatment apparatus of the present invention comprises a flocculation part into which water to be treated is introduced, at least two flocculant adding devices installed so that different flocculants can be added to the flocculation part, one or two or more water quality measurement devices for measuring the quality of the water to be treated, and a controlling part for issuing, on the basis of the measurement result from the water quality measurement device(s), a command relating to whether addition of the flocculants to the corresponding flocculant adding device is required or not and to the added amounts of the flocculants, wherein at least one of the flocculant adding devices is an auxiliary flocculant adding device.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55, 57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes a installable and removable valve controller housing (74) which is releasably engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

An apparatus for controlling output in a water treatment plant treating water includes: a chemical dosing management part configured to analyze real-time data to determine a control mode of chemical dosing optimization, and provide the determined control mode as a management command; a chemical dosing optimization part configured to analyze the real-time data to derive a control value such that the control value is to set a minimum of a chemical dosage to be dose in the water while a state of treated water of the water treatment plant is maintained in a normal range; and a chemical dosing output control part configured to provide the control value to a water treatment control device for controlling the water treatment plant, according to the control mode of the management command.

A method treats an aqueous system to inhibit growth of one or more micro-organisms therein and/or to reduce the number of live micro-organisms therein. The method includes adding treatment agents to an aqueous system wherein said treatment agents include (a) a phosphonium compound; and (b) a compound having formula: M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2.

A method treats an aqueous system to inhibit growth of one or more micro-organisms therein and/or to reduce the number of live micro-organisms therein. The method includes adding treatment agents to an aqueous system wherein said treatment agents include (a) a phosphonium compound; and (b) a compound having formula: M(XO.sub.2).sub.n wherein: M is a Group I or Group II metal; X is a halogen; and n is 1 or 2.

Processes for producing olefins may include electrolyzing an aqueous solution comprising metal chloride, where electrolyzing the aqueous solution causes at least a portion of the metal chloride to undergo chemical reaction to produce a treatment composition comprising hypochlorite. The processes may further include contacting at least a portion of the treatment composition with the sour water at a pH from 8 to 12, where the sour water comprises sulfides and the contacting causes reaction of the sulfides in the sour water with the hypochlorite to produce a treated aqueous mixture comprising at least metal sulfates and metal chlorides, where the metal sulfates are present in the treated aqueous mixture as precipitated solids. The processes may further include separating the precipitated solids from the treated aqueous mixture to produce a treated effluent comprising at least the metal chloride.

A closed conduit system for use in a water supply system includes a recirculating unit configured to connect to an isolated section between a first point and a second point of the water supply system. The recirculating unit includes a first filter unit defining a first closed circuit including the isolated section and adapted to perform a first treatment. A second filter unit defines a second closed circuit including the isolated section and is adapted to perform a second treatment. At least one pump is capable of generating a flow of water through the first and the second closed circuit, and a valve selectively controls flow through either the first or the second closed circuit.

The methods disclosed generally relate to treatment of process water using chlorine dioxide. Specifically, reactants may be fed asynchronously into a diluent line or a tank where the reactants may mix and react to form chlorine dioxide. The chlorine dioxide levels may fluctuate in the diluent line or the tank thereby inhibiting or reducing the growth of microbes.

The methods disclosed generally relate to treatment of process water using chlorine dioxide. Specifically, reactants may be fed asynchronously into a diluent line or a tank where the reactants may mix and react to form chlorine dioxide. The chlorine dioxide levels may fluctuate in the diluent line or the tank thereby inhibiting or reducing the growth of microbes.

Described herein are solid compositions for water treatment of swimming pools and spas. The solid composition comprises, in a single solid product in the form of a tablet, puck, briquette, a capsule, powder mix or the like, a combined source of a plurality of chemical compounds such as chlorine, algaecide, clarifier and pH adjuster. In embodiments the solid composition comprises at least a combination of (i) a source of chlorine for killing bacteria and (ii) a neutralizer for ensuring a proper pH balance. In embodiments the solid composition is be formulated as a bilayer. In embodiments the solid composition is formulated as a bilayer, a first layer comprising sodium dichloroisocyanurate (NaDCC) and a second layer comprising trichloroisocyanuric acid (TCCA).