Sludge volume index automatic measurement unit

Water quality measurement equipmentSludge volume index automatic measurement unit (SVI meter)

This unit automatically measures sludge volume (SVt and SV30), sludge concentration (MLSS) and sludge volume index (SVI) of the sludge mixture at sewerage treatment plant using the activated sludge process.

Product Features

To determine quality of solid-liquid separation at the final sedimentation tank, SVI indicating settleability of sludge is required as the index for sedimentation of sludge as well as SV30. In addition, by SVI measurement, optimal control of excess sludge amount and return sludge volume becomes possible. Currently, since this SVI is measured by using the beaker test, it requires time and labor. Since an optical detector is used for this device and it is equipped with a cleaning device, V, MLSS and SVI can be automatically and continuously measured in a short time. In addition, maintenance of this unit is easy.

  • Output signal can be received remotely: thus status of sludge (settling character, SVt value, SV30, MLSS and SVI, etc.) can be grasped at any place.
  • As an air lift pump is used for sampling, flock of sludge is hardly broken.
  • By adopting a large-diameter measurement pipe, it can obtain sedimentation characteristic without the imfluence of wall-effect, etc.
  • Since this meter is equipped with a cleaning mechanism to prevent contamination at the inner wall of the measurement tube, it can offer long-term automatic measurement without maintenance.


Item SVI meter
Type SVI-401
Measuring object SV MLSS SVI
Sludge capacity of the sludge mixture is automatically measured at sewerage treatment facilities using the activated sludge process (SVt, SV30). Sludge concentration (MLSS) Sludge capacity index (SVI)
Measuring method Interface tracking type by use of transmitted light Scattered light comparison type Calculation by use of SV30 and MLSS
Measuring range 0 to 90%
(indicated value 0 to 100%)
500 to 5,000 mg/L (indicated value: 0 to 5,000 mg/L) Either 0 to 250 mL/g or 0 to 500 mL/g
Measurement accuracy Repeatability ±0.5% ±5% (F.S. after calibration) ±1%
Output signal DC4 to 20 mA (maximum load resistance: 500 Ω)
(However, hold output is used for MLSS and SVI.) MLSS is DC4 to 20 mA at 0 to 5,000 mg/L.
Ambient environmental conditions temperature -5 to 50°C (no freezing)
Power source AC100 V 50/60 Hz 1.5 kVA Single phase
Configuration of measuring circuit Contactless type by use of semiconductor and IC
Cycle time 1 cycle: 50 minutes (In case of measurement of SV30)
Sampling Automatic sampling type by use of air lift pump
Sampling pump Method Air-lift pump
Air Vane pump KRX-1 type
125/145 L/min 0.05 MPa
AC100 V single phase 50/60 Hz 0.5 kW
Quantity 1
Cleaning method Automatic cleaning with vertical motion of brush in the measuring pipe
External dimensions W 1000 x H 1800 x D 1000 mm
Weight Approx. 750 kg
  • * We also produce the meter in which only SV is measured and SVI is calculated and output by externally inputting MLSS.