A defined role in your monitoring routine.
A representative return-activated-sludge sample can be checked with the S3A when its concentration and characteristics fall within the instrument specification. Return-stream readings need to be considered in their own sampling context.
The specified MLSS range is 50–6,500 mg/L. Results above 6,500 mg/L are shown as INF; they are not a quantified concentration above that limit. Confirm suitability with PMA if the expected sample is outside the stated range.
From a representative sample to a recorded result.
Prepare the sample
Collect a representative sample using the site’s procedure. Use a 210 ml sample and confirm that the expected MLSS is within the specified 50–6,500 mg/L range. Readings above 6,500 mg/L are indicated as INF.
Run the test
S3A provides an MLSS result in approximately 10 seconds, followed by a 30-minute unattended settlement cycle. Standard outputs include SVI, settled sludge level, supernatant clarity and floating sludge.
Review in context
Review completed measurements alongside the sample identity and site observations. Store up to 28 completed results for each of three internal locations, with date and time.
Keep return and mixed-liquor records distinct
Use a consistent location/profile and clear sample identification. Compare the measurements alongside the treatment works’ existing observations and procedures.
Calibration and optional measurements
Calibrate with a site-specific sample of known MLSS between 2,000 and 4,000 mg/L. Repeat after large changes in sludge characteristics. SSVI and SSSL require the optional stirrer module.
Optional connection to a client system.
Specify optional MODBUS RTU over two-wire RS-485 when ordering. Read functions 03/04 provide supported readings to a compatible client system; dashboards and integration are client-provided. Function 06 is limited to Holding Register 40001 for the slave ID (1–247), not measurement writes or test control.
Operational measurement, not a replacement for required laboratory analysis.
S3A supports operational checks of activated sludge. Required compliance sampling, regulatory testing and laboratory analysis must still follow the procedures that apply to the site.
Operate indoors in a safe area at 0–45°C, in noncondensing conditions and away from direct and reflected sunlight. Follow the current manual and the treatment works’ safety and sampling procedures.
Continue your application review.
Measurement parameters
Explore the S3A measurement parameters for activated sludge, including MLSS, SVI, settled sludge level, supernatant clarity and floating sludge.
Explore guideS3A product details
Explore the portable S3A suspended solids and MLSS analyser for activated sludge: 210 ml sample, rapid MLSS result and 30-minute settlement cycle.
Explore guideContact PMA
Contact PMA UK to discuss S3A applications, product information, demonstrations, technical support, calibration and wastewater settlement testing.
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