Device and method for measuring settleability of activated sludge in-situ

A method for in-situ measuring settleability of activated sludge using a device, the device comprising:

• 1) a sample chamber comprising a stagnant zone;
• 2) an ultrasonic time domain reflectometer;
• 3) a magnetic stirrer;
• 4) an ultrasonic probe;
• 5) a sample inlet;
• and
• 6) a sample outlet;
• wherein:
• the sample chamber is configured to hold an activated sludge sample, and the ultrasonic time domain reflectometer is configured to measure settling characteristics of the activated sludge sample;
• the sample inlet and the sample outlet communicate with the sample chamber;
• the stagnant zone comprises a top part, a sidewall, and a bottom part;
• the sample inlet is connected to the top part of the stagnant zone;
• the sample outlet is connected to the sidewall of the stagnant zone;
• the magnetic stirrer is disposed at the bottom part of the stagnant zone;
• and
• the ultrasonic probe is disposed on the top part of the stagnant zone;
• and the ultrasonic time domain reflectometer is connected to the ultrasonic probe to transmit signals;
• the method comprising:
• 1) collecting an activated sludge sample in a target location using a constant flow peristaltic pump;
• 2) guiding the activated sludge sample from the sample inlet into the stagnant zone;
• starting the magnetic stirrer to mix the activated sludge sample where exhaust gas is produced;
• and removing the exhaust gas out of the stagnant zone through an exhaust pipe communicating with the stagnant zone;
• 3) stopping the magnetic stirrer;
• turning on the ultrasonic time domain reflectometer to control the ultrasonic probe to emit an ultrasonic signal to monitor the activated sludge sample in the stagnant zone for 30 minutes;
• collecting the ultrasonic signal by an oscilloscope of the ultrasonic time domain reflectometer, and showing an ultrasonic waveform change diagram over time;
• 4) forming a sludge settling displacement curve according to the ultrasonic waveform change diagram;
• 5) obtaining a displacement value at 30th minute according to the sludge settling displacement curve;
• and calculating a sludge volume index (SVI) according to a fitted equation;
• and
• 6) removing the activated sludge sample out of the stagnant zone through a peristaltic pump.