Consulting | Intervention to improve wastewater treatment plant performance

Constructed Wetlands also offers diagnostic and technical consulting services for existing wastewater treatment plants (WWTPs) with the goal of increasing efficiency and/or diagnosing process and/or operational failures. In this particular study, the company was responsible for the diagnosis, action plan/interventions, and training to improve the performance of an existing compact WWTP for treating sanitary effluents from an administrative building at a mining unit. The plant, composed of activated sludge reactors with extended aeration and polishing with physicochemical treatment, was exhibiting low organic load removal efficiencies (less than 60%), insufficient to meet legal requirements and well below design efficiencies.

The company then conducted a detailed technical and operational diagnosis with the following investigations:
- Evaluation of influent flows and loads to the treatment system;
- Evaluation of existing monitoring data for the treatment system;
- Evaluation of the water/moisture ratio of the biological process;
- Determination of the SVI (Sludge Viability Index) of the activated sludge;
- Analysis of the sludge microbiology; - Overall assessment of equipment and processes;

- Verification of conformity between the WWTP design and the implemented/operational structures;

- Checking the operational parameters of the design and those currently in effect in the existing structures;

- Checking current maintenance routines;

- Verification of the automation system programming and operational cycles of the WWTP in question;

After the diagnosis, revisions were made to the operating routines, adjustments were made to the WWTP's automation parameters, and the operational team was trained, accompanied by assisted operation until the WWTP's performance was restored.

The interventions were effective, and the WWTP returned to achieving the design efficiencies (greater than 95% for organic load removal).

One of the technical studies requested by the client, for the composition of the diagnosis, consisted of the microbiological analysis of the sludge, as shown in the project's cover image. This analysis revealed the poor biodiversity of the microfauna, with a predominance of stalked ciliates and rhizopods, without the presence of filamentous bacteria, low concentration of free and flagellated ciliates, characteristics of sludge with poor treatability and low nitrification potential. One of the causes for this characteristic of sludge with poor treatability is possibly associated with high concentrations of dissolved oxygen and low concentration of BOD. This was precisely one of the points observed in the field investigations to justify the poor performance of the wastewater treatment plant.