Pre-Sedimentation Systems for Water Treatment PlantsWhen considering pre-sedimentation (pre-sed) systems for water treatment plants, it is essen...
Published on by Hossein Ataei Far, Deputy Manager of the Research, Technology Development, and Industry Relations Center at NWWEC
When considering pre-sedimentation (pre-sed) systems for water treatment plants, it is essential to understand local conditions and consult with experienced engineers. Different approaches may be suitable for different plants. Key pre-sed system designs include earthen lagoons, concrete basins with serpentine channels, and concrete basin clarifiers.
#### 🌿 Earthen Lagoons
- **Advantages:**
- Long detention times (days), allowing plants to manage peak solids and turbidity events.
- Economical due to lower construction time, material, and design costs.
- **Disadvantages:**
- Require large amounts of land.
- Potential freezing issues in cold climates ❄️.
- May need additional pumping to integrate with existing plant hydraulics.
- Short-circuiting, leading to reduced detention times.
- Solids turnover in larger lagoons, causing treatment disruptions.
- Labor-intensive cleaning, typically done annually, requiring de-watering and drying over several months 🧹.
- **Design Consideration:**
- Often constructed in parallel to allow one lagoon to be operational while the other is cleaned.
#### 🏗️ Concrete Basins with Serpentine Channels
- **Characteristics:**
- Suitable for chemical additions with short detention times (15-60 minutes) for oxidation.
- Example: Fort Peck Water Treatment Plant.
- Sodium permanganate is added to oxidize organics and enhance filtration.
- Followed by coagulant addition, flocculation, and high-rate settling for turbidity removal.
#### 💧 Concrete Basin Clarifiers
- **Performance:**
- Can remove 50-90% of turbidity based on raw water quality.
- Example: Fort Peck pre-sed basins.
- **Process:**
- Includes coagulant addition, rapid mixing, flocculation, and high-rate settling with inclined plate settlers.
- Solids are conveyed to on-site earthen setting lagoons for evaporation or land application.
### Conclusion
A well-designed pre-sed system must be tailored to local conditions and specific needs. Numerous factors influence the design and selection of the appropriate pre-sed system. Consulting with professionals, such as the team at Morrison-Maierle, ensures that the most effective and efficient solutions are implemented for water treatment plants in various locations, like Montana.
Reference:
[1] https://lnkd.in/dEwkuq6K