Wastewater New York State Practice Exam

What is the typical MLSS concentration range of an SBR?

1. 1,000 to 3,000 mg/L

2. 2,000 to 6,000 mg/L

3. 5,000 to 10,000 mg/L

4. 8,000 to 12,000 mg/L

The correct answer is: 2,000 to 6,000 mg/L

The typical Mixed Liquor Suspended Solids (MLSS) concentration range for a Sequence Batch Reactor (SBR) is often found to be between 2,000 and 6,000 mg/L. This range is considered optimal for effective biological treatment processes within the SBR system. In SBRs, the concentration of MLSS is crucial because it impacts the efficiency of the treatment process, the settling characteristics of the sludge, and ultimately the quality of the effluent. The concentration range of 2,000 to 6,000 mg/L allows for sufficient biomass to promote effective microbial activity necessary for the degradation of organic matter during the aeration phase. It also avoids issues that can arise from excessively high concentrations, such as poor settling and separation during the decanting phase. The lower end of this range supports the growth of microorganisms without overwhelming the system, while the upper end ensures that there is enough biomass to handle varying loads and improve treatment efficiency. Thus, this range is well-established in the operation of SBR systems.