This “batch system” respirometer consists of: a single thermostatically controlled vessel, divided into two interconnected compartments with closed recirculation loop between the two. A constant air flow is supplied via a ceramic diffuser in the conditioning compartment, and a combined oxygen/temperature sensor in the reaction compartment controls the DO and temperature. Both compartments are kept completely mixed by means of paddle stirrers and a peristaltic recirculation pump.
The BM‐EVO is doted by three different operation modes (Static, Cyclic and Dynamic).
In this study we are only making use of the dynamic R mode for toxicity and biomass yield followed by the COD fractioning and COD removal rate.
The R mode is based on the addition of one or several small sample doses in the returned activated sludge previously aerated in the reactor vessel.
For R mode the measuring system was previously calibrated to get the corresponding offsets and factors with the purpose to determine the corresponding CO and bCOD results in mg/l units.
Data capture & handling together with respirometer control is performed by the powerful BM software loaded onto a permanently connected PC. The automatically derived parameters generated by that BM‐EVO include:
- OUR (mgO2/l.h) : Oxygen Uptake Rate.
- SOUR (mgO2/gVSS.h) : Specific OUR ‐ by introducing the MLVSS concentration ‐
- Rs (mgO2/l.h) : Dynamic Respiration Rate.
- Rsp (mgO2/gVSS.h) : Specific Rs ‐ by introducing the MLVSS concentration –
- CO (mg/L) : Consumed Oxygen
- bCOD & rbCOD (mg/L) : Biodegradable & Readily biodegradable COD – by introducing YH