**Part 8: Bioindicators for Early Detection of Operational Issues**Using Protozoan Analysis and the Sludge Biotic Index (SBI)*1. **Balanced *Vor...
Published on by Hossein Ataei Far, Deputy Manager of the Research, Technology Development, and Industry Relations Center at NWWEC
*Using Protozoan Analysis and the Sludge Biotic Index (SBI)*
1. **Balanced *Vorticella* Populations**
- **Function**: Balanced populations of *Vorticella* protozoa indicate that wastewater treatment plants (WWTPs) operate with optimal oxygenation and manageable organic load. These sessile protozoans thrive in well-aerated systems, reflecting stable operating conditions.
- **Impact**: *Vorticella* contributes to better floc formation, improving sedimentation and effluent clarity. This results in smoother downstream processes and improved water quality (Xiao et al., 2021).
2. **Imbalances in Protozoan Populations**
- **Problem**: Overabundance of specific species, such as *Vorticella microstoma*, often signals insufficient oxygen levels or an overloaded system.
- **Monitoring Benefits**: Detecting these imbalances early allows operators to adjust aeration rates or reduce organic load, mitigating potential system failures (Zhang et al., 2023).
*Key Protozoan Indicators and Their Roles*
- **Positive Indicators**:
- *Epistylis rotans*: Associated with high water quality and effective treatment processes, indicating optimal aeration and microbial balance.
- *Arcella sp.*: A positive indicator of nitrification and proper oxygen levels in the system, critical for complete biological treatment.
- **Potential Warning Indicators**:
- *Aspidisca cicada*: Signals acceptable system performance but may highlight sporadic toxic inputs, necessitating further investigation.
- *Vorticella microstoma*: Suggests insufficient oxygenation or a high organic load, indicating system stress or imbalance (dos Santos et al., 2014).
*Research Insights from Protozoan Studies*
- **SBI as a Diagnostic Tool**:
- Protozoan-based monitoring, including the SBI, provides operational insights into suspended solids, oxygenation levels, and overall system health. While SBI scores may not directly predict effluent quality metrics such as COD and BOD5, they serve as an effective early-warning system for operational adjustments (dos Santos et al., 2014).
- **Correlations with Treatment Parameters**:
- Studies reveal that specific protozoan populations correlate strongly with factors such as total suspended solids (TSS) and dissolved oxygen (DO), emphasizing their value as indicators for system health.
References:
[1] Drewnowski, et al. (2019).
[2] Sid, et al. (2017).
[3] Singh, et al. (2012).
[4] Water Environment Federation (WEF) (2021).
[5] Environmental Protection Agency (EPA).
[6] European Commission (2022).
[7] Xiao, Y., et al. (2021).
[8] Zhang, Q., et al. (2023).
[9] dos Santos, L. A., et al. (2014).
[10] Ren, Z., et al. (2022).
This picture is shown in this article: Rudakova, et al. 2019. Biomonitoring in the control system of biological wastewater treatment in pulp and paper industry
Floc formers of active sludge. A -floc formers of active sludge under average load