Florida Wastewater Practice Test

Which chemical is typically used for the dechlorination of final effluent?

1. Chlorine

2. Hydrochloric Acid

3. Sulfur Dioxide

4. Ozone

The correct answer is: Sulfur Dioxide

The use of sulfur dioxide for dechlorination of final effluent is a common practice in wastewater treatment. Sulfur dioxide reacts with residual chlorine in the effluent, converting it into harmless chloride ions. This process is critical because the presence of chlorine in treated wastewater can be toxic to aquatic life when the effluent is discharged into receiving waters. By neutralizing chlorine with sulfur dioxide, wastewater facilities can ensure that the discharged effluent meets environmental discharge standards and protects the health of ecosystems. Other options are not utilized for dechlorination in this context. Chlorine is itself a disinfectant and would not serve to remove chlorine from effluent. Hydrochloric acid may have uses in other chemical reactions or pH adjustment but is not specifically used for dechlorination. Ozone can also function as a disinfectant; however, it is not typically used for the dechlorination of final effluent in the same manner as sulfur dioxide. This understanding of sulfur dioxide’s role is crucial for wastewater operators to maintain compliance with environmental regulations.