This standard specifies the requirements for the design, materials, construction, and installation of settling tanks (clarifiers) used for solid-liquid separation in wastewater treatment. It covers key design parameters like surface overflow rate, detention time, and weir loading, as well as mechanical equipment such as scraper mechanisms and drive units.
Requirements for settling tank (clarifier equipment) for wastewater treatment
Quick Reference Values
Typical Surface Overflow Rate (Primary Settling)25 - 50 m³/m²/day
Typical Detention Time (Primary Settling)1.5 - 2.5 hours
Typical Surface Overflow Rate (Secondary Settling)15 - 30 m³/m²/day
Maximum Weir Loading Rate185 m³/m/day
Scraper Tip Speed (Circular Tank)0.02 - 0.05 m/s
Minimum Tank Bottom Slope1:12 (or 8%)
Key Formulas
Surface Area (A) = Design Flow (Q) / Surface Overflow Rate (SOR)
Detention Time (t) = Tank Volume (V) / Design Flow (Q)
Practical Notes
This standard is foundational but has been largely superseded by the IS 14594 series. For new projects, the newer codes should be consulted.
The design parameters provided are general guidelines; actual values should be based on treatability studies of the specific wastewater.
Proper specification of the scraper drive mechanism (Clause 7) is critical to ensure long-term operational reliability and prevent breakdowns.