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Why water

HWT is a water services provider. The company was founded in 1994 and since then, has successfully designed, built and commissioned in excess of 100 treatment plants. In general, the treatment plants are fully automated, requiring minimal operator intervention.

Our design philosophy consistently favours process and cost efficiency. Typical projects include treatment of;

domestic sewage
industrial effluent
food processing waste water
winery and cellar effluent
potable/drinking water

Additionally, HWT offers process maintenance and effluent management solutions.

Potable water treatment plants need to be reliable, efficient and robust. This is how potable water treatment plants are designed at HWT;

Reliable. Fully automated treatment processes with alarm for mal-function.

Efficient. Appropriate technology for the application. Guaranteed compliance with legislative standards.

Robust. Construction materials include stainless steel and HDPE. Vital equipment redundancy.

Potable water treatment plants by region

Potable water is derived from various sources. In broad brush strokes, potable water can be obtained from ground or surface waters. Ground water would be from wells and springs. Surface waters are generally classed as lakes, dams and rivers. Rainwater would most likely be classed as a surface water.

The nature of the potable water is heavily influenced by region.

For example the Western Cape ground waters are often discoloured by dissolved organic acids, tend to be low in pH and have varying concentrations of iron and manganese.

In other parts of the country and in particular on the West Coast, the ground water tends to be quite saline. Apart from the unpleasant taste, this type of water can be corrosive and harmful to health.

Potable water treatment plants – choosing the right process

Potable water treatment plants vary in complexity. In each instance they would be designed to make use of the most suitable technology. For example Theewaterskloof water. This is a mixture of river and spring water. It has varying and seasonal turbidity. Generally the pH is on the low side with some dissolved iron.

Typically a flocculation treatment process affords a viable solution. This is the chosen route for a number of Municipal sized water treatment plants.

However for smaller applications such as a wine cellar or restaurant, alternative technologies are more appropriate. Although flocculation works well, the addition of flocculant has to be monitored extremely carefully.

Treatment plants can be skid mounted or fabricated within a shipping container.

Potable water treatment plants

Potable water treatment plants


At HWT, sewage treatment plants of all types are designed, constructed and operated.  The treatment plants are constructed in concrete, in containers and in custom made tanks – choice of material is always a function of suitability and efficiency.  Some are mini sewage treatment plants, some are package treatment plants and some are fully fledged biological sewage treatment plants on a Municipal scale.
For sewage treatment plant design, there are multiple biological methods available to the design engineer.  In broad brush strokes, biological sewage treatment can be engineered in a liquid or wet environment.  The liquid environment includes all variations of the activated sludge process.  A wet environment is one such as found in a french drain or a trickling SOG filter.

Before the war, sewage treatment was no biggie.  It was the Roman aqueducts which provided the large volumes of water needed to scour the sewers after the water had performed numerous civic functions, including the supply of water to the many public baths.  The system comprised 11 aqueducts supplying the city with water from as far away as the river Anio.  For those in the technical know, sewage is the liquid waste and sewerage is the infrastructure required to get sewage from point of release to point of disposal.  A sewage treatment plant treats sewage using all manner of sewerage connections and equipment.

The management and maintenance involved in keeping the aqueducts flowing is well described by Julius Frontinus, a general appointed by the emperor Nerva as water commissioner towards the end of the first century AD.  He described his work on the distribution system in his published volume – De aquaeductu.  When first appointed he surveyed and mapped the entire water supply system.  He also meticulously investigated the many abuses, in particular unauthourised abstraction.  Maintenance of the aqueducts was introduced with groups of specially trained workmen. Frontinus also tried to separate the supply so that only the best quality water was provided for drinking and cooking, while lesser quality water was used for the fountains, baths and finally flushing of the sewers.

The composition of sewage has changed hugely since the time of Frontinus.   Eating patterns are vastly different and enormously variable.  Processed and synthetic foodstuffs are present in unprecedented quantities as too are preservatives and colourants.  Sugar and salt intakes today would made kings of the past salivate with envy.

Sewage Treatment Plant

Sewage treatment the world over predominantly makes use of a combination of mechanical and biological treatment processes.  Although great improvements have been made since the early 1900’s, the unit treatment processes have not changed significantly.  We are still very dependent on naturally occurring bacteria to clean up after us.

sewage treatment plant

The modern sewage treatment plant design engineer, if nothing else, knows how to make an environment in which bacteria will thrive.

At HWT, we strive to make our sewage treatment plants unobtrusive, quiet and maintenance free.

Have a look at some of our completed projects