When treatment processes are arranged one after the other, this is referred to as?

When treatment processes are arranged one after the other, this is referred to as series operation. In a series operation, the output of one treatment step becomes the input for the next step, effectively treating the wastewater in a linear progression. This arrangement allows for a more comprehensive treatment as each subsequent process can address remaining contaminants that might not have been fully removed in the previous step.

For instance, in a wastewater treatment plant, primary treatment might remove solids, secondary treatment would then focus on organic matter and nutrients, and tertiary treatment could target remaining pollutants or pathogens. By structuring the processes in series, the treatment system can achieve a higher level of effectiveness and efficiency in removing various types of contaminants from the wastewater.

The other options reflect different operational strategies but do not accurately describe the concept of arranging treatment processes consecutively. Concurrent operation typically refers to processes that occur simultaneously rather than in a sequence. Sequential treatment may seem similar but does not specifically denote the arrangement of processes in a single line. Flow-through operation generally describes systems that transport wastewater continuously through treatment steps but does not specifically indicate the arrangement as being sequential.