Abstract: In electrodialysis for desalting or concentrating an electrolyte solution in desalting chambers and concentrating chambers constituted by alternately juxtaposing a plurality of anion and cation exchange membranes between at least a pair of electrodes by supplying the electrolyte solution into the desalting and concentrating chambers while introducing a gas in a bubble state into the electrolyte solution between the ion exchange membranes, the electrolyte solution is made to contact the gas in the bubble state while providing a temperature difference between the gas and the electrolyte solution. The scale deposition onto the ion exchange membranes is prevented with an increase in electrodialysis efficiency.

Abstract: The present invention relates to an apparatus for removing suspended matter, organic matter and nitrogen compounds in the sewage. A processing tank is provided with a floating-separation zone at the upper portion thereof and an electrolysis zone below the floating-separation zone. A bed of porous adsorbent is disposed in the electrolysis zone and electrodes are disposed among the adsorbent. Bubbles generated upon the feed of current to the electrodes rise up through the floating-separation zone to remove the suspended matter and the organic matter in the sewage before introducing the sewage into the electrolysis zone. The porous adsorbent is polarized by the feed of current to the electrodes and results in removing matter remaining in the sewages, especially nitrogen compounds.

Abstract: The present invention relates to a method for removing suspended matter, organic matter, foaming matter and nitrogen compounds in sewage and to an apparatus for the method.The suspended matter and the organic matter are removed by means of first fine bubbles and the foaming matter is removed by means of second bubbles having a larger bubble average diameter. The sewage treated by the first and second bubbles passes through a bed of porous adsorbent polarized by the feed of current, so that nitrogen compounds and the organic matter remained in the sewage are adsorbed and removed. It is also provided with a step for removing the suspended matter and the organic matter remained in the sewage by means of third fine bubbles before transferring the sewage to the bed of adsorbent.

Abstract: An apparatus and process for tubular membrane separation, such as reverse osmosis or ultrafiltration, with an arrangement for removing undesirable deposits from the semipermeable membrane surfaces. For the removal of the deposits, elastic elements are passed, together with the feed solution being treated, through the tubular modules lined with semipermeable membranes, separated from the solution, and are recycled with a fresh supply of the solution from a tank, so that the semipermeable membranes are continuously cleaned while separating a part of the solution by permeation therethrough.

Abstract: To remove salts from a solution containing the salts, hot air is injected downwards into the solution in a concentrator, and the solution is concentrated by direct contact with the hot air, thereby enhancing an evaporation efficiency in the concentrator and preventing scale deposition in the concentrator and piping system. The solution is forcedly cooled in a crystallizer by direct contact with cool air, thereby making crystals grow in the solution within a short time. The solution and air are circulated in a closed cycle, thereby preventing a secondary environmental pollution.

Abstract: A method of regenerating zeolite by heating wherein zeolite having adsorbed (NH.sub.3 -N) in foul water has sodium hydroxide added thereto, the sodium hydroxide containing Na.sup.+ equivalent to NH.sub.4.sup.+ adsorbed to the zeolite, water is added until the total quantity of the zeolite is submerged, and the resultant zeolite is heated at 400.degree. C. for 30 minutes, whereby a regeneration rate of 90% is attained.

Abstract: In regenerating an adsorbent by eliminating water and an adsorbed matter which are contained therein, the adsorbent is indirectly heated while descending within a drying furnace and is indirectly heated while ascending within a regenerating furnace in order to prevent the adsorbent from scattering due to water vapor and the adsorbed gas separated by the heating of the adsorbent and to prevent the adsorbent from burning itself due to heat.

Abstract: A tubular membrane separation apparatus and process, for reverse osmosis or ultrafiltration, with an arrangement for removing undesirable deposit from semipermeable membrane surfaces. The apparatus is of the multiple-stage type wherein the number of tubular modules per stage gradually decreases in a pattern like a Christmas tree laid on its side. Elastic elements are forced through the tubular modules lined with the semipermeable membrane, the number of the elements being gradually decreased stage by stage, so that the deposit is mechanically rubbed off from the membrane surfaces with an optimum number of elastic elements for each stage.

Abstract: A filtration method employs a water tank, a filtration tank within the water tank and provided with a filter material for straining solids from sewage supplied to the water tank, to produce filtered water within the filtration tank, a shield or guide plate encompassing the filtration tank adjacent the filter material to provide a liquid flow passage therebetween, and a bubble generator having a plurality of openings for generating bubbles within the flow zone, so that the bubbles pass along the filter material. Sewage water that is supplied to the water tank is conducted to the flow zone where part of the water passes through the filter material and solids suspended therein are strained out and attached to the outer surface of the filter material.

Abstract: Dialysis apparatus has dilution and concentration chambers arranged alternately, which chambers each are defined by ion exchange membranes and frames each disposed therebetween. Passages for introduction of air into the dilution and concentration chambers are provided at lower portions thereof. The air introduced through the passages into the dilution and concentration chambers rises upward between the ion exchange membranes and is exhausted from upper portions thereof out of the dialysis apparatus. By the introduction of the air, solutions in the dilution and concentration chambers are driven to flow upward. Condensed phosphates are added to liquid to be treated before dialysis of the liquid.

Abstract: In a process for electro-dialysis which comprises passing an electrolyte through dilution chambers and concentration chambers formed between a large number of alternately counterposed anion exchange membranes and cation exchange membranes, and applying an electric potential to a pair of electrodes provided at both ends of a plurality of these chambers, thereby migrating ions in the electrolyte through the membranes and effecting dilution or concentration of the electrolyte, such a volumic rate of air bubbles is introduced to the lower parts of the dilution chambers as to make the thickness of a diffusion layer formed by concentration polarization near the ion exchange membranes in the dilution chambers smaller than when air bubbles are not introduced thereto, and make the resistance between the electrodes smaller than when the air bubbles are not introduced thereto. Superficial air velocity of air bubbles introduced into the dilution chambers is preferably 1-4 cm/sec.

Abstract: Method of and apparatus for separation of solids from a liquid employs an elastic sheet filter which has pores of diameter larger than an average diameter of the solid and smaller than the maximum diameter thereof. The liquid is filtered under pressure by a filtered residue layer developed on the sheet filter. Then liquid is rapidly introduced to the sheet filter portion from the reverse direction to liquid flow occured during the filtration of the liquid so that the sheet filter and filtered residue layer pressed during the filtration is rapidly pressed in the reverse direction, whereby the filtered residue layer is flaked out in the liquid and separated therefrom.

Abstract: A system is provided for separating waste water or solution into a permea solution and a concentrated solution by feeding the waste water or solution to a reverse osmosis apparatus using a membrane.A chemical pretreating apparatus is provided to prevent hard scales contained in the waste water or solution from precipitation during the concentration in the reverse osmosis apparatus using the membrane. An apparatus for charging sponge balls is further provided to mechanically remove suspended solids and other suspended matters, that is, soft scales when deposited on the surface of membrane. The sponge balls are desirably recyclically used.

Abstract: A multi-stage distillation plant consisting essentially of a multi-flash evaporator provided with a multi-flash chamber which is divided into a heat recovery section and a heat rejection section. In this multi-stage flash distillation plant, the aforesaid flash evaporator is provided with a deaerator for deaerating cold sea water, a thickener for separating brine containing a relatively great amount of seeds, from concentrated brine which has been extracted from a front chamber of the final stage flash chamber, and a seed mixing tank for obtaining a seed-mixed brine, whereby part of the sea water which has passed through the deaerator is supplied as a feed sea water to the rear chamber of the final stage flash chamber, while the brine containing a relatively great amount of seed and extracted from the thickener is joined to the seed-mixed brine fed from the seed mixing tank.