Implementation of Automatic Monitoring and Control System in Balloon Digester Type’s Biogas Plant from Tofu Waste Using Ultrasonic Distance Sensor

Abstract

Biogas plant is a name often given to digesters that treat waste or sewage into biogas. The monitoring system is an important process to know the quality and quantity of gas produced and understand the processes inside the plant to achieve the optimum process. The monitoring process can be carried out by measuring the volume of biogas collected in the gas holder and the concentration of biogas produced (especially CH4 gas). The manual method of monitoring and control system used a pressure gauge to estimate the volume of biogas. An automatic device was designed and tested for monitoring and controlling gasbag volume by using an ultrasonic sensor. This device measures the distance between the sensor to the surface of the gasbag and calculates it into volume. The sensors contained in this device had a good level of performance with a percentage error of 0.2% and a standard deviation of 0.32 cm. At the same time, the system design has a good level of performance to calculate the volume with a percentage value of 2.51% and a standard deviation of 0.18 cm. The designed system also has proper performance response, shown by the LED indicator turns off and the socket turns on when it reaches the setpoint. The results showed that the volume of the gasbag used in the plant had a maximum capacity of 102.984 kiloliters and a minimum capacity of 58.857 kiloliters, with a total filling time of 30.5 hours and a usage time of up to 12.5 hours.