Risk of Collapse in Water Quality in the Guandu River (Rio de Janeiro, Brazil)

Area of Science:

• Environmental Science
• Water Quality Management
• Ecotoxicology

Background:

• The Guandu River is a vital water source for over nine million people in Rio de Janeiro.
• Decades of domestic and industrial pollution have severely degraded water quality, particularly during summer months.
• Elevated levels of phosphorus, cyanobacteria, and enteric bacteria pose significant risks.

Purpose of the Study:

• To assess the current poor water quality of the Guandu River.
• To evaluate the ineffectiveness of Phoslock as a phosphorus mitigation strategy.
• To document the undesirable side effects of Phoslock treatment.

Main Methods:

• Analysis of water quality parameters, including phosphorus, cyanobacteria, and bacterial counts.
• Assessment of Phoslock's efficacy in reducing phosphorus levels.
• Sensory evaluation of potable water for taste and odor issues (2-MIB/geosmin).

Main Results:

• High concentrations of dissolved total phosphorus, cyanobacteria, and enteric bacteria were confirmed.
• Phoslock treatment proved ineffective in mitigating phosphorus levels.
• Potable water exhibited undesirable mud-like taste and odor due to 2-MIB/geosmin.

Conclusions:

• The Guandu River's water quality remains critically poor.
• Phoslock is not a viable solution for phosphorus control in this context.
• Urgent implementation of comprehensive solutions like sewage treatment and environmental recovery is necessary.