In this applied research, a plant controller with capacity of 300 litres has been developed. The system provides graphical user interface (graphics and tables) using Visual Basic program to show and monitor the fermentation process. Communication between the software and hardware is established through microcontroller’s interface. The microcontroller acts as the main controller which controls the humidity, temperature, pH, aerator, heater, exhaust fan, and the speed of the motor. Temperature and humidity sensor (DHT-22), Methane Gas sensor (CH), Carbon Gas sensor (MQ7), and Nitrogen Gas sensor (MiCS-2714) are used in this system. The domestic waste raw materials such as vegetables and sugar cane waste are thinly sliced while the fruits are grinded. Temperature, humidity, and pH readings are collected as reference parameters prior to the process starts. During the anaerobic digestion process, temperature is kept at 40°C ±1 while plant’s tube is maintained at 40°C. When the temperature falls to 39°C, the heater is switched on, when the temperature reach 40°C the heater is switched off. This research is carried on using two kind of mixture models which are: mixture model X (mixture of vegetables, fruits and sugar cane waste) and mixture model Y (same as X with additional rice husk). The mixture model X and Y C/N’s ratio is in compliance with SNI-7030-2004 standard. The real-time plant controller system proposed in this research is successfully.

In this applied research, a solar energy powered process control monitoring system of inorganic fertilizer plant with capacity of 300 liters has been developed. The process control system consists of PLC with solar energy panel as its power source and a monitoring process system. The monitoring process system includes a Raspberry Pi minicomputer, an LCD touchscreen, level shifter converters, Arduino Nano, RS485 modules, four analog sensors, and one digital sensor. This system works by collecting temperature, humidity, and gas concentrations data and controlling the heater, exhaust fan, and aerator to maintain desired processing conditions.DHT-22 digital sensor measures temperature and humidity, pH probe analog sensor measures pH values, MQ-4, MQ-7 and MiCS-2714 measures methane, carbon monoxide, and nitrogen dioxide gases respectively. Analog output sensor is read by PLC’s analog to digital converter while digital output sensor is read by 1-wire bus by Arduino. The collected data is send over RS485 to Raspberry Pi. The plant temperature is set constant at 40°C. The heater is turned on at temperature of ≤ 38°C, when temperature reach ≤ 42°C the aerator, exhaust fan, and mixer will be on and will be switched off all together at 40°C. The temperature, humidity and PH are set as the reference of the control process.

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