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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.

Design philosophy 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.

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

Drinking (potable) water is derived from various sources. Broadly, potable water can be abstracted from the ground or collected from surface waters. Ground water is found in boreholes, 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 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.

Sewage Treatment

HWT designs, constructs and operates sewage treatment plants of all types.  Treatment plants can be constructed in concrete, in containers or making use of 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 composition of sewage has changed hugely since Roman times.   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.

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

HWT sewage treatment plants are unobtrusive, quiet and maintenance free.

16 x 6m container sewage treatment plant