Current online water quality monitoring methods and their suitability ...
Current online water quality monitoring methods and their suitability ...
Current online water quality monitoring methods and their suitability ...
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eliability for continuous <strong>water</strong> <strong>quality</strong> <strong>monitoring</strong> within each barrier in the PRW system. It onlyprovides recommendations based on researchers’ <strong>and</strong> industry experience with <strong>online</strong> analysers.5.1 Organic Load IndicatorsOnline parameters that can indicate the organic load of the <strong>water</strong> source are essential to ensure theintegrity of all barriers within the PRW closed loop system. This is primarily because the PRW isdesigned to remove organic matter from the waste<strong>water</strong> to produce high purity drinking <strong>water</strong>. Inaddition, organic levels in Barriers 6 <strong>and</strong> 7 can cause disinfection by-product formation, <strong>and</strong> <strong>their</strong>presence is also used as a surrogate to indicate microbial contamination 4, 78 .Table 2loadingsOrganic parameters or indicators required to be measured at each barrier to indicate organicParameter B1 B2 B3 B4 B5 B6 B7 CommerciallyAvailableBOD 5 √ √ YesCOD √ √ YesTOC √ √ √ YesDOC √ √ YesSuspendedSolids√ √ √ √ YesTurbidity √ √ √ √ √ √ √ YesCommercially Available SensorsTable 2 lists the parameters required to be measured at each barrier to indicate organic loadings.<strong>Current</strong>ly there are <strong>online</strong> sensors available for <strong>monitoring</strong> all of these parameters; however <strong>their</strong><strong>suitability</strong> for Barriers 1, 2 <strong>and</strong> 2/3 is questionable due to the variability in the matrix composition (seeAppendix 1 for more information).BOD 5There are a number of instruments commercially available: those which use various means to measurethe oxygen respiration rate of sewage sludge, <strong>and</strong> those based on chemometric algorithms to estimateBOD from UV-visible absorption. Some examples are given below:AppliTek Ra-BOD® On-line BOD analyzerDirect BOD measurement using respiration rate (mgO 2 /l.h) of sludge from the WWTPEndress+Hauser Biox-1010This rapidly measures BOD 5 from the dilution factor required to keep the DO level constant in a small<strong>online</strong> bioreactor fed by waste<strong>water</strong> diluted with air saturated <strong>water</strong>.Advantages: Has a high measuring range; <strong>and</strong> Does not require chemicals.Disadvantages: Requires sample conditioning.s::can; Endress+Hauser StipscanThese employ UV-Vis absorption <strong>and</strong> chemometric algorithms to quantify BOD 5 non-destructively inreal-time. They use the spectral absorbance values around 250-380 nm to indirectly quantify BODusing UV-Vis absorption patterns.<strong>Current</strong> Online Water Quality Monitoring Methods <strong>and</strong> Their Suitability for the Western CorridorPurified Recycled Water Scheme Page 18
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