The accurate formula for calculating total suspended solids in raw wastewater is that total suspended solids are equal to the sum of non-settleable solids and settleable solids. This is a fundamental concept in wastewater treatment, as total suspended solids (TSS) represent the concentration of particles in wastewater that can remain suspended under standard conditions.
In raw wastewater, settleable solids are those that will settle to the bottom of a clarifier or sedimentation tank due to gravity, while non-settleable solids remain suspended and do not settle quickly. By combining these two categories, you can derive the total amount of suspended solids present in the wastewater, which is a key parameter for understanding treatment needs and performance.
Other formulations provided, such as the notion of subtracting non-settleable from settleable solids, do not align with the established definitions and relationships within wastewater solids characterization. This differentiation is crucial for proper monitoring and management of treatment processes, ensuring that the plant operates efficiently and meets regulatory requirements.