EVERY DROP COUNTS. Clean water is becoming a scarce resource. There is an increasing need to treat wastewater, both in developed countries and emerging countries alike. New wastewater treatment plants are continually being built in Latin America, Asia and Africa.
¹Source: The United Nations Water and Sanitation Goals Report 2023
²Source: United States Environmental Protection Agency
³Source: Global Wastewater Status United Nations University
Many water treatment plants have now severely aged and suffered various degrees of degradation – mostly due to biogenic corrosion in areal parts of confined pits and primary treatment tanks in the wastewater treatment plant.
To comply with new micropollutant regulations, water treatment processes must also be upgraded, and quaternary treatment may be required.
Count on Sika’s expertise to help solve this and related problems in wastewater treatment plants.
Key Factors Affecting Concrete Durability
- Chemical attack: Wastewater – especially industrial wastewater – often contains aggressive substances like sulfates, chlorides, and organic acids.
- Microbiological activity: Bacteria and other microorganisms used for the water treatment can contribute to concrete degradation through processes like sulfate-reducing bacteria (SRB) activity and biological sulfuric acid attack (BSA) leading to acid production.
- Abrasion and erosion: The flow of wastewater, especially in pipes, channels, and primary treatment tanks, can cause mechanical wear and tear on concrete surfaces.
- Freeze-thaw cycles: In regions with fluctuating temperatures, repeated freezing and thawing can lead to cracking and spalling of concrete.
- Steel reinforcement corrosion: Exposure to chlorides, moisture, and acidic environments in wastewater treatment plants can lead to the corrosion of embedded steel reinforcement.
What You Should Consider Prior to the Project
Before defining the repair and protection strategy, the specific sewage treatment plant requirements on refurbishment must be considered. These requirements can have an important influence in determining the correct design, planning and construction procedures, together with the future maintenance works necessary for the sewage treatment plant.
Examples of such project related requirements include:
Durability
Duration of closure / Downtime
System compatibility
Total life cycle costing
Exposures / Site Conditions
Ecology
1. Screening Channel
In a large treatment plant, the removal of large objects is automatically performed in the screening channel.
Problem
In waste water treatment plants, erosion is mainly due to abrasion or by chemical attack. Erosion damage results from the abrasive effect of waterborne silt, sand, gravel, and other debris being circulated over a concrete surface during operation. The compounds present in hardened Portland cement are attacked by the aggressiveness (low pH) of the waste water.
Sika Solution
Sika MonoTop®-3400 Abraroc
Problem
Chemical attacks, depending on the aggressiveness of the waste or industrial water.
Sika Solution
Sikagard®-720 EpoCem®
Sikagard®-63 N
Sikagard®-7000 CR
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete.
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex® PRO-3
Sika® Injection-451
Sikaflex®-403 Tank & Silo
Problem
Damage in concrete due to microbial induced corrosion (MIC) in covered areas where the sewage is in a turbulent flow.
Sika Solution
Sika MonoTop®-4400 MIC
Sikagard®-7000 CR
2. Grit, Fat & Grease Removal Chamber
In some plants, pre-treatment may include a grit channel where the wastewater velocity is adjusted to allow settlement of the sands/grits or other hard particles. Sands/grits must be removed as they may damage pumps or other equipment. Fat and grease removal is generally done in a large plant in the primary settlement tank using mechanical surface skimmers.
Problem
Abrasion and erosion due to sand, grit or other particles.
Sika Solution
Sika MonoTop®-3400 Abraroc
Problem
Chemical attacks depending on the aggressiveness of the waste or industrial water.
Sika Solution
Sikagard®-720 EpoCem®
Sikagard®-63 N
Sikagard®-7000 CR
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete. Very often in waste water treatment, joints sealed with average sealant fails due to the lack of chemical resistance to these products. Instead of proceeding to the full removal of the failed joint, Sika has developed a joint system that can be applied over the original failed material.
The Sikadur-Combiflex® SG system is the second generation development of the globally proven Sikadur-Combiflex® with even improved performance such as advanced adhesion properties. The unique system consists of the Sikadur Combiflex® SG tape and the Sikadur® adhesives. It is widely used as joint waterproofing in watertight concrete structures.
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex® PRO-3
Sikaflex®-403 Tank & Silo
Problem
Microbial induced corrosion (MIC) in covered areas where the sewage is in turbulent flow
Sika Solution
Sika MonoTop®-4400 MIC
Sikagard®-7000 CR
3. Primary Sedimentation Tanks
In the primary sedimentation tank, sewage flows through large tanks, commonly named “primary clarifiers” or “primary sedimentation tanks”. These tanks are equipped with mechanically driven scrappers that drive the collected sludge towards a hopper. Some primary sedimentation tanks can be covered to control odor. In such conditions, they can be subjected to biogenic corrosion.
Problem
Chemical attacks depending on the aggressiveness of the waste or industrial water.
Sika Solution
Sikagard®-720 EpoCem®
Sikagard®-63 N
Sikagard®-7000 CR
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex® PRO-3
Sikaflex®-403 Tank & Silo
Problem
Abrasion and erosion due to sand, grit or other particles at the bottom of the concrete floor.
Concrete spalling due to sulfate attack or other aggressors on the wall of the tank.
Sika Solution
Sika MonoTop®-4012
SikaTop® Armatec®-110 EpoCem®
Sika MonoTop®-3400 Abraroc
Problem
Heavy abrasion on the rolling pad of the scrapper.
Sika Solution
Sikadur®-42
Sika® Icosit®-KC 330 FK
Problem
In covered areas of tanks, biogenic corrosion may occur - leading to microbial induced corrosion (MIC).
Sika Solution
Sika MonoTop®-4400 MIC
Sikagard®-7000 CR
4. Aerated & Anoxic Biological Tanks
Biological tanks are designed to substantially degrade the biological content of the sewage. These biological contents are originated from human waste, soap, and detergents.
Problem
Chemical attacks depending on the aggressiveness of the waste or industrial water.
Sika Solution
Sikagard®-720 EpoCem®
Sikagard®-7000 CR
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete.
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex® PRO-3
Sikaflex®-403 Tank & Silo
Problem
Concrete spalling due to reinforcement steel corrosion.
Sika Solutions
Sika MonoTop®-4080 repair mortar
SikaTop® Armatec®-110 EpoCem® rebar protection
5. Secondary Sedimentation Tanks
Secondary treatment is intended to degrade further the organic content of sewage water originating from human waste, soap, detergent, etc. Most of the plants treat the sewage using aerobic biological processes.
Problem
Erosion due to water flow
Sika Solution
Sikagard®-720 EpoCem®
Problem
The water has already received some treatment, hence the level of chemical aggressiveness in this sedimentation tank is reduced.
Sika Solution
Sikagard®-720 EpoCem® can be used alone in secondary treatment tanks
Sikagard®-7000 CR
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex® PRO-3
Problem
Steel reinforcement corrosion due to reduced concrete cover.
Sika Solution
Sika MonoTop®-4012
SikaTop® Armatec®-110 EpoCem®
6. Filtration Beds
In the filtration bed, the treated water flows through various layers of sand beds for final filtration before being discharged in the environment. Filters are periodically cleaned using air and clean water at the counter stream. The cleansing water is then pumped back to the aeration basin for retreatment.
Problem
Abrasion and erosion due to sand, grit or other particles.
Sika Solution
Sika MonoTop®-3400 Abraroc
Problem
Chemical attacks depending on the aggressiveness of the waste or industrial water.
Sika Solution
Sikagard®-720 EpoCem®
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete.
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex® PRO-3
7. Digestion Tanks
The sewage sludge digestion tank is where the sludge is stabilized, reduced in volume, made innocuous through the process of dissolving organic substance with the help of anaerobic bacteria and finally, where energy is recovered.
Problem
Abrasion and erosion due to sand, grit or other particles.
Sika Solution
Sika MonoTop®-3400 Abraroc
Problem
Concrete or steel above the sludge may suffer heavy attack due to the formation of the sulfuric acid. Additional stress is caused by the elevated temperature originating from the biological process. Downtimes always create problems and difficulties for the owners, as well as the loss of money. Sika offers solvent-free, high build coating systems that can be applied in one layer on a well-prepared surface. Therefore, downtimes can be minimized without the reduction of protective properties.
Sika Solution
Sikagard®-7000 CR
Sikalastic®-8440
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete.
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex®-403 Tank & Silo
8. Gasometers
Within the process of biological deterioration in the biological tank or the digestion tank, biogas (methane, CO²) will be produced and be stored in gasometers. These gasometers are generally built-in steel. Biogenic sulfuric acid is highly aggressive to steel. Additional stresses are caused by the elevated temperature.
Problem
Concrete or steel above the sludge may suffer heavy attack due to the formation of the sulfuric acid. Additional stress is caused by the elevated temperature originating from the biological process. Downtimes always create problems and difficulties for the owners, as well as the loss of money. Sika offers solvent-free, high build coating systems that can be applied in one layer on a well-prepared surface. Therefore, downtimes can be minimized without the reduction of protective properties.
Sika Solution
Sikagard®-7000 CR
Sikalastic®-8440
Problem
Leakage and risk of pollution due to cracks, untight joints or damaged concrete.
Sika Solution
Sikadur-Combiflex® SG System
Sikaflex®-403 Tank & Silo
9. External Basement Waterproofing
To keep drinking water in below-ground storage tanks clean, it has to be protected from groundwater entering the structure.
Sika Solutions
SikaProof® A+ pre-applied, fully-bonded TPO membrane
SikaProof®-808 pre-applied, fully-bonded TPO membrane
Sika Solutions
SikaShield® W pre- and post-applied, wet-bonded bitumen waterproofing membrane, self-protected by a cross-laminated HDPE film
Sika® Igolflex® bitumen based liquid coating
10. Service Buildings, Concrete & Masonry Exterior
Most waste water treatment plants have a technical service building. External surfaces of the building as well as of the above-ground tanks are exposed to weathering and therefore often need protection.
Problem
In these technical buildings, chemicals are handled. Therefore, the floors in the chemical storage area also need protection.
Sika Solution
Sikafloor®- 381
Sika® Ucrete® MF
Problem
Roofs in the buildings (technical and office) of the sewage treatment plants may require waterproofing.
Sika Solution
Sarnafil® PVC or FPO membranes
Sikalastic® liquid applied membranes
SikaShield® bitumen membranes
Problem
External concrete surfaces may undergo natural weathering due to carbonation. When the plant is located close to the sea, they may also suffer chloride attack.
Sika Solution
Hydrophobic impregnations: Sikagard®-705 L and Sikagard® H 303
Protective coatings: Sikagard®-675 W ElastoColor and Sikagard®-5500
Problem
External masonry surfaces may undergo natural weathering due to water penetration that may lead to mold growth and reduced thermal performance of the structure.
Sika Solution
Hydrophobic impregnation: Sikagard®-703 W
Sika's Expert Knowhow & Solutions
Systems Plus Knowhow: Sika's Holistic Approach to Water Infrastructure
Sika empowers water infrastructure owners, architects, engineers, operators, and contractors with comprehensive support, ensuring project success.
Our commitment extends beyond providing high-quality products; we offer:
Expert Guidance
- In-depth technical advice and assistance throughout the project lifecycle.
- Comprehensive support for refurbishment projects, including specification development, detailing, method statements, and application guidance.
- Expertise in designing new structures for long-term durability.
Cost-Effective Solutions
- Sika's expertise minimizes overall project costs by optimizing performance and extending service life.
Comprehensive Product Portfolio
Sika delivers a complete range of durable and reliable solutions specifically engineered for demanding water infrastructure applications, including:
- Concrete admixtures
- Waterproofing membranes
- Concrete protection coatings
- Watertight joint systems
- Concrete repair and reinforcement systems
Sika’s Experts Provide Assistance to Benefit your Business
Local Contact
Contact a Sika expert near you for technical support and locally available products and systems.
Global Project Support
Sika’s Project Support Team provides in-depth consultative support for our full product range and represents a single point of contact into the extensive Sika network of experts. Please contact us to learn more or inquire specifically on your current project(s).
