Towards a hydrodynamically enhanced design and operation of primary settling tanks – Results of a long term in situ measurement investigation program

Abstract

AbstractIn modern wastewater treatment the function of primary settling tanks (PSTs) has become more complex comprising the control of readily biodegradable carbon between denitrification and biogas production by an optimum performance. This requires detailed investigations in order to obtain exact knowledge of the processes within PSTs. The article shows the results of the investigation of a PST comprising in situ flow measurements and removal efficiency analysis. The measurements were carried out at different surface overflow rates, which ranged from low to even higher values than those recommended by design guidelines. This was done in order to investigate the relationship between hydrodynamic processes and removal efficiency at high hydraulic loads. Inflowing and outflowing suspended solids concentrations and loads were recorded on‐line during the measurements. The measurements provided detailed insight into the flow processes within the PST as a first step towards hydrodynamically driven design and operation control of PSTs.