Oxygen uptake at Parshall flumes
Parshall flumes are frequently used to measure flow at municipal wastewater treatment plants. With the flume causing turbulent flow, there is the potential for the emission of volatile organic compounds. To assess the extent of the emissions, laboratory and field measurements at Parshall flumes were completed, using oxygen as a surrogate. The laboratory measurements showed that the most important parameters influencing oxygen uptake were total energy loss and downstream water depth. Satisfactory results were also obtained using drop height. Field results from three municipal wastewater treatment plants showed that oxygen uptake correlated strongly with drop height and only slightly with discharge rate. This is beneficial as downstream water depth is difficult to measure in the field. Findings suggest that the use of an appropriate weir model would allow the estimation of oxygen uptake and volatile organic compounds stripping at Parshall flumes.Key words: oxygen uptake, volatile organic compounds, flumes, wastewater.