Desalination refers to the removal of salts and minerals from water. PROXA has extensive experience in the application and design of optimal desalination solutions that are energy efficient, minimizes brine streams and reduce operational input & maintenance requirements.
Desalination refers to the removal of salts and minerals from water. PROXA has extensive experience in the application and design of optimal desalination solutions that are energy efficient, minimizes brine streams and reduce operational input & maintenance requirements.
Our desalination expertise covers
Brackish water desalination technologies can be divided into two main groups: ion exchange and reverse osmosis. Ion exchange is the most widely applied and more economical for desalination of waters with a low salt content. This market is currently dominated by reverse osmosis technology due to its favourable economics in the brackish water range.
PROXA has extensive experience in the use of brackish water membranes for the desalination of surface, water, process water and effluent. These brackish water systems operate at pressures of 8 – 25 bar (g) and water recoveries of 55 – 99%. Both of which is determined by the feed water composition. Brackish water RO systems are also commonly used in double pass mode to produce ultra pure water for boiler applications.
The treatment of mine waters to recover potable water is a well known and proven technology. The bigger challenge is what to do with the resultant salts that are now concentrated into a smaller brine stream in a cost effective manner. The protection of the environment, space limitations related to the building of new brine ponds and long term legacy risks led the PROXA R&D teams to focus on sustainable brine treatment solutions.
Numerous Zero Liquid brine generation (ZLD) mine water treatment plants have been built by PROXA using a range of different technologies and solutions depending on the composition of the clients feed water, specifically calcium and sodium ions.
In some cases it is possible to achieve ZLD using only membrane processes with the salts being safely exported back into the environment from where they came.
In other cases where high levels of monovalent ions are present (for example sodium), thermal processes are required to treat the highly concentrated brine stream, to recover salt crystals.
Thermal processes include either heating the solution up to boil off and recover the water or freezing to recover the water as ice. In both cases the resultant salt is left behind in a solid form. In addition, PROXA has been a key player in piloting of Eutectic freeze crystallisation for the selective recovery of high purity saleable by-products from brines.
PROXA has used both heating and freezing to produce by-products from mine water effluents.
Our ability to control water chemistry and selectively target specific components in effluent has a significant advantage in ensuring that effluent waters are safe for discharge or alternately can be used to produce drinking water in water scarce areas.
Brine treatment has become an area of concern for the mines due to the high level of salts stored on site, the associated legacy risk and the volumes required for storage. Maximising water recovery from mine waters using membrane processes ensures cost effective solutions.
PROXA has been able to achieve recoveries exceeding 99% using membrane process. The resultant small volume, highly concentrated salt or brine stream can then be treated further to recover the salts in a solid form where required. PROXA has a number of references for brine treatment of sodium and gypsiferous feeds and is the only company running more than five zero liquid brine (ZLD) generation sites at full production in Africa.
Another key advantage from our ability to control water chemistry is to selectively remove high quality saleable products from brine. These products include, amongst others, gypsum used in construction, sodium sulphate used in the detergent manufacture and phosphates used in fertiliser.
PROXA has developed and implemented brine treatment solutions which are cost effective and meet all legislative requirements throughout South Africa, Zambia, Mozambique, Zimbabwe, Tanzania, Ghana, Namibia and Botswana.
A key requirement in all desalination applications is the management or disposal of the salts and minerals removed from the water (brine).
PROXA is a leader in brine management solutions as well as recovery of valuable by-products from these highly concentrated waste streams with multiple references in a wide range of applications, for example:
PROXA serves a number of industrial sectors, including: mining, power, petrochemical, steel, mineral, food & beverage and more. In each of these sectors water plays a critical role in the various processes being employed.
However, this process water is often contaminated and needs to be treated prior to discharge, or reuse for alternative applications. PROXA has assisted a number of clients in treating their process water to various qualities for reuse elsewhere on the plant. Process water and/or contaminated effluent can also be treated to qualities suitable for human consumption where water can be distributed to communities.
The treatment required depends on the contaminants present in the process water, and the quality required for either reuse of the process water or for discharge to the environment. In some instances, clients need to treat their potable water further for use as process water where a superior quality is required, such as boiler feed water. PROXA has the experience, skill and technology available to tailor the treatment process to the client requirement on a case-by-case basis.
Sewage treatment is the process of removing pollution from household sewage. It includes physical, chemical, and biological processes to remove pollutants and produce environmentally safe treated wastewater.
Normally, the heart of the sewage treatment system is the activated sludge process, which removes organic pollution, and nitrogen and phosphorous compounds, if required.
The activated sludge process may be preceded by grit removal, primary clarification and equalization and superseded by sand filtration, ultra-filtration, maturation, disinfection etc. A by-product of sewage treatment is usually a semi-solid waste or slurry, called waste activated sludge (WAS), that has to undergo further treatment/stabilisation before being suitable for disposal or land application. In most cases, the bulk of the wastewater treated is of household (or municipal) origin, but a fraction can also be of industrial origin.
Sewage treatment systems can vary in size from 2.4 million person equivalent Stickney sewage treatment plant in Illinois to modular “package plants” suitable for treatment of as little as 10 to a few hundred person equivalents. Sewage treatment systems can also vary in complexity ranging from rudimentary reed beds and trickling filters in developing countries to energy efficient moving bed bioreactors (MBBRs) and highly advanced membrane bioreactors that implements ultra-filtration membranes to ensure superior effluent quality. PROXA has in-house design and build capacity to supply both MBBR and MBR turnkey packaged solutions in this field. PROXA has a number of references in this area.
We provide optimum solutions through unrivalled experience in:
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