WASTEWATER

WEAR PROTECTION IN WASTEWATER MANAGEMENT SYSTEMS

The Th. Scholten GmbH & Co. KG applies its proven wear protection solutions from the SC-AwaTec® product line to water and wastewater management systems. These packages, which comprise a variety of different materials like cast basalt or hard ceramic, and in particular special installation mortar, offer solutions in terms of corrosion protection, protection against abrasion, and protection against BSC (biogenic sulphuric acid corrosion) in combination with the corresponding process technologies.

Areas of application include sewer construction and sewer rehabilitation projects, sewage treatment plants, and other structures requiring additional long-term and sustainable protection. For optimum installation and sealing, Scholten offers cement-based mortar which meets the increasingly higher requirements and increasingly stricter environmental regulations.

The photo shows a trough conveyor pump station that was lined with cast basalt using the Reith procedure. Not only the crescent-shaped spiral trough was lined, but also the side walls, the head, and the sump pit were lined with SC cast basalt tiles.

PULHEIM PURIFICATION PLANT

The Pulheim purification plant was put into operation in 1982 and was expanded in 1994. In 2007, the Th. Scholten GmbH & Co. KG rehabilitated the first two spiral troughs with cast basalt with the result that it has not shown any signs of wear in five years of operation.

The situation in the purification plant: In light of the rough operating conditions resulting in a high susceptibility to wear, the concrete linings of the spiral troughs in particular suffer from pitting corrosion due to sulphuric acid. After contracting an expert report, the management decided in mid-2012 to replace the concrete trenches with cast basalt trenches from the Th. Scholten GmbH & Co. KG.
This economical material consisting primarily of silicon dioxide and aluminium oxide is not only resistant to corrosion caused by alkalis and acids (except for hydrofluoric acid), but has also proven itself over decades of use for applications in damp and chemically aggressive operating conditions and materials.
Scholten was contracted to partially rehabilitate the spiral troughs and both pump pits in addition to completely lining the entire screw pump with cast basalt and the associated comprehensive rehabilitation of the concrete according to the applicable concrete rehabilitation guidelines.

Technical details:
The Pulheim purification plant is equipped with four screw pumps with a diameter of 900 millimetres each as well as four more with a diameter of 1.200 millimetres each, over a length of 10.500 millimetres per screw pump. The experts from Th. Scholten GmbH & Co. KG installed prefabricated troughs made exactly to size in the Wülfrath factory in the concrete troughs already moulded to size during the concrete rehabilitation process. During installation, the 30 millimetre thick cast basalt tiles were joined in a mould and preassembled to form elements with a length of 500 millimetres each. At the site in Pulheim, a crane inserted the elements, each of which weighed about 90 kilos, in the six precisely pre-fabricated troughs so that they, when placed next to each other, completely covered the bed of the screws and precisely reflected the profile of the screw pumps.

Mortar was back-filled to precisely fit and fasten the troughs in the concrete bed, and for the surfaces having contact with wastewater, epoxy resin was used instead of mortar. There is only a gap of five millimetres between the feed screw and the cast basalt trench.
In addition to the troughs, the inner concrete surfaces of both pump pits (walls, stairs, and transitions), a total of 100 m² was lined with 22 millimetre thick cast basalt tiles. This guarantees that all inner concrete surfaces have long-term protection against biogenic sulphuric acid corrosion (BSC).

HIGH-PERFORMANCE MORTAR FOR THE WASTEWATER INDUSTRY

The sustainable prevention and cost-effective repair of systems in need of renovation is an ongoing issue in the wastewater management sector. Both wastewater treatment plants, primarily capped structures and open screw troughs, as well as wastewater infrastructure in the form of shafts, pumping stations and sewer pipes require durable and reliable protection.

Mortar systems
A wide range of highly-modified mortar systems – specially tailored to the requirements of the wastewater sector – have been used successfully for years and enable the permanent and extremely economical renovation of wastewater infrastructure.

The highlight: geopolymer mortar
Geopolymer mortar is a solution for the reliable protection of wastewater engineering structures in highly acidic environments, even well below pH 3, as it is a mineral system that is open to diffusion with the advantage of a permanent bond to the substrate and, in contrast to cementitious mortars, offers permanent protection against biogenic sulphuric acid. It reliably prevents the dreaded, frequently occurring biogenic sulphuric acid corrosion (BSK) and protects the structures permanently against renewed damage. The material is classified in exposure class XWW4 in accordance with DIN 19573 and meets the highest requirements.
This product is also used as a laying mortar or jointing mortar for fused cast basalt slabs/elements and has also proven to be an excellent addition to existing materials in this area of application.
The geopolymer mortar is applied to the previously adequately prepared, load-bearing substrates by hand, for example, in layer thicknesses of 9 to 20 millimetres per work step on the previously applied bonding bridge due to its high adhesive strength. Application using the wet stream spraying method or the spin-on method is particularly economical.

Shaft coated using centrifugal technology

Coating a walkable channel using the wet flow method with conventional machine technology

Our mortars – including geopolymer mortars – are manufactured in Germany in accordance with DIN EN 998-2: 2016 with the corresponding control mechanisms to ensure consistently high quality.

Geopolymer mortars have many advantages, some of which are unique and unbeatable when combined:
Permanent protection against biogenic sulphuric acid (BSK)
Pumpable up to 100 m hose length, even in hot weather
100 % more area coverage possible in the wet spraying process
Fiber-reinforced, therefore 25-50 % higher bending/tensile strength
Permanently resistant to media temperatures of up to 250 °C
Resistant to freeze-thaw and de-icing salt, also highly sulphate-resistant
High layer thicknesses when applied by hand – even with single-layer application
Can withstand water for short periods
Very good adhesive strength – “new layer on old layer” without any problems
Very good adhesive tensile strength
Impermeable to water and seals against pressing groundwater
Up to 75 % CO2 savings during production

The successful use of well over 25,000 tons of our geopolymer mortar worldwide in over 200 major projects provides a secure basis with sound experience, even when tackling challenging construction projects and geometries – in a proven manner and in close coordination with all parties involved.