THE DETERMINATION OF SETTLED SLUDGE VOLUME AND SLUDGE VOLUME INDEX USING PROCESS METHODOLOGIES

摘要

One of the key analytical parameters used to assess the performance of typical municipal wastewater processes is the determination of the settled sludge volume (SV) within the aeration basin. Commonly, this measurement method is performed on a bench scale using a settlometer. This method is sensitive to sampling technique, agitation methods, variations in suspension, process temperature, dimensions of the settling column, and the amount of time between sampling and the start of the determination; all of which can significantly affect results. The test is time-consuming and because of this it is typically performed only once per day. To help eliminate the difficulty in performing the SV measurement, an on-line instrument has been designed to continuously perform the measurement on-site. The methodology includes: purging of the previous sample, accepting a new sample, and performing the measurement. The instrument design includes a uniquely shaped settlometer vessel. This specially designed vessel facilitates the settling rate and reduces the analysis time. A shortened cycle time for each measurement is the result. An on-line SV instrument has been installed in the aeration basin of a local municipal wastewater plant. This installation has provided data that can be compared directly to the laboratory values for this method. This installation site also provides the opportunity to calculate Sludge Volume Index (SVI) when the total suspended solids (TSS) measurements from the aeration basin are considered. The use of this process monitoring technology to determine the critical SVI of the wastewater plant provides information to allow plant performance to be controlled real-time.