Csir

Council of Scientific and Industrial Research

Tshwane University of Technology

Phillert Trust

Roc Water Technologies (pty) Ltd

Roc Water Technologies Ltd

Johannes Philippus Maree

Andries Gerber

John A Clayton

Wynand Jacobus Louw

Tabani Mtombeni

Guido Kamiel Erik Bieseman

A water treatment process () includes, in a crystallisation stage (), passing a saline water feed () through an elongate conduit kept in a cold environment at a temperature below the equilibrium freezing temperature of the saline water, forming a slurry of brine and ice crystals inside the conduit, and, in a separation stage (), separating the ice crystals from a bulk of the brine, producing a brine stream () and an ice stream (). The elongate conduit is of a material, or has an inner material layer in contact with the saline water and with the slurry of brine and ice crystals, with a thermal conductivity of less than 5 W/m·K and has a length configured to ensure formation of the slurry of brine and ice crystals in the conduit at the flow rate of the saline water feed through the elongate conduit.

Treatment of water

A process to treat water includes adding a salt-forming base to the water thereby producing saline water, or thereby forming a salt in the water which is different from a salt that the water started out with, if the water started out as saline. The saline water is treated, at a temperature Twhich is above the saturation temperature of the saline water, in a first membrane separation stage to provide clean water and a first brine, the salinity of the first brine being higher than the salinity of the saline water. The first brine is cooled to a temperature Tto precipitate some of the salt from the first brine and the precipitated salt is separated from the first brine producing a second brine, the temperature Tbeing below the temperature Tbut above the freezing temperature of the first brine. The second brine is treated at a temperature Tabove the saturation temperature of the second brine in a second membrane separation stage to provide clean water and a third brine. The salt-forming base, the temperature Tand the temperature Tare selected so that the salt which is formed in the saline water has a solubility in water at the temperature Twhich is at least 1.5 times the solubility of the salt in water at the temperature T

A process for treating impure water includes adding magnesium hydroxide and/or ammonium hydroxide to the water. This neutralizes the impure water and reacts with dissolved metals in the water. The metals are precipitated as metal hydroxides/oxides, which are removed from the water. Thereafter barium hydroxide is added to the water. The barium hydroxide reacts with dissolved sulphates to produce barium sulphate and, when magnesium hydroxide is used, with dissolved magnesium, to produce magnesium hydroxide. Barium sulphate and, when present, magnesium hydroxide are removed from the water. When ammonium hydroxide is used, ammonia is stripped from the water. Carbon dioxide is then added to the water. The carbon dioxide reacts with dissolved calcium in the water. The calcium is precipitated as calcium carbonate, which is removed from the water.

A method of treating water to remove fluoride ions from the water, thereby to reduce the dissolved fluoride content of the water, is provided. The method includes, in a contacting step, contacting water containing dissolved fluoride ions with alumina, to cause the fluoride ions to react with and become bound to the alumina. In a regenerating step, the alumina, when spent, is regenerated to drive off fluoride ions bound thereto. The regenerated alumina is recycled to the contacting step where it is used to remove further fluoride ions from the water. The fluoride ions driven off the alumina in the regenerating step are passed on to downstream processing thereof.

Water treatment

A water treatment process for raw water containing dissolved Fe and H cations to reduce the Fe &plus; cation concentration therein involves oxidation of the Fe cations to Fe cations with the formation in the water of solid Fe(OH) from the Fe cations. The process comprises the steps of oxygenating the water and raising the pH of the water. The oxidation of the Fe cations and the fromation of the Fe(OH) are carried out in the presence of suspended particulate material in the water, the particulate material being present in the water at a concentration of at least 5 g/l.

Treatment of acidic water containing dissolved ferrous cations

A process for treating water having anions comprising sulfur and oxygen dissolved therein involves subjecting the anions to an anaerobic biological reduction to sulfide anions dissolved in the water, followed by a biological oxidation of the sulfide anions to elemental sulfur suspended in the water. The sulfur is separated from the water. The reduction and oxidation are effected together in a series of common reaction stages in which there are oxidizing conditions which permit the biological oxidation without preventing the biological reduction.

Process for treatment of sulphate-containing water

A water quality improvement process is provided for acid water containing sulphate and/or sulphite ions. The water is continuously fed into a fluidized bed containing calcium carbonate particles. The water consumes calcium carbonate and has its pH increased while calcium sulphate CaSO.sub.4 and/or CaSO.sub.3 are produced.

The invention provides a chemical process for the treatment of water containing dissolved calcium and sulphate ions, so as to produce a purified product water having a reduced sulphate ion concentration. Barium sulphide is added to the water to cause precipitation of barium sulphate from the water. The water from which the barium sulphate has been precipitated is then treated with carbon dioxide to form hydrogen sulphide in the water, and the hydrogen sulphide is stripped from the water.

Water treatment for sulfate ion removal

The invention provides a process for the treatment of water containing dissolved calcium ions and dissolved sulphate ions. The water is passed at a pH of 5-8,5 through an anaerobic biological sulphate removal stage wherein microorganisms utilize sulphate ions in the water to produce hydrogen sulphide. The water from the sulphate removal stage is then passed through a hydrogen sulphide removal stage where hydrogen sulphide is removed therefrom. Water form the hydrogen sulphide removal stage is passed through an aerobic biological treatment stage wherein microorganisms cause at least partial biodegradation of any organic material remaining in the water and wherein calcium carbonate is precipitated. The invention also provides a biological water treatment installation which comprises an enclosed reservoir means which provides an anaerobic stage and which feeds into a hydrogen sulphide removal stge, which feeds into a reservoir means having oxygenating means therein for oxygenating water therein and providing an aerobic stage.

Growing community of inventors

Pretoria, South Africa

Johannes Philippus Maree