Prototipe sistem peringatan dini berbasis SMS untuk mendeteksi kenaikan kadar gas amoniak di pengolahan air limbah industri penyamakan kulit

The objective of this research was to produce prototype of an early warning system based on SMS for detection the rising level of ammonia gas in wastewater treatment of leather tanning industry. The systems consist of three parts, those were data input, data processing, and output. Ammonia gas sensor as a detector that produces an analog Direct Current (DC) voltage. Analog to Digital Converter (ADC) pin on the microcontroller received an analog DC voltage to be processed. ADC readings done through the Liquid Crystal Display (LCD) while the Global System for Mobile Communications (GSM) modem was used to send Short Massage Service (SMS). This early warning system worked by determining a threshold value. SMS would be sent to hand phone number of job holder, if the ADC value exceeded the specified threshold value. Result obtained was the ammonia gas sensor model are MQ137 based on SnO , Arduino Uno as 2 microcontroller module based on Atmega 328P microcontroller, and General Packet Radio Service (GPRS) Shield as GSM modem that compatible with the Arduino Uno R3 pin.