Solids Retention Time

The solids retention time (SRT) is the time the solid fraction of the wastewater spends in a treatment unit. It is the quantity of solids maintained in the reactor divided by the quantity of solids coming out of the reactor each day: SRT = V *Cd / Qout* Cout. Where V is the digester volume; Cd is the solids concentration; Qout is the volume wasted each day and Cout is the solids concentration of the effluent. In a conventional, completely mixed, or plug flow reactor, the HRT equals the SRT. In retaining biomass reactors (e.g. anaerobic biogas settlers, septic tanks) the SRT exceeds the HRT.


Glossary Term Name

Legacy NID


Legacy VID