Design and development of a low-cost ammonia monitoring system for water quality assessment

Abstract

This thesis presents a low-cost ammonia detection and monitoring system for freshwater fish farming. The system uses an MQ-137 gas sensor, Arduino Uno, heater, water pump, thermocouple, and LCD display to measure ammonia concentration in water samples. The sensor was calibrated using known ammonia concentrations and a fourth-order polynomial model to convert sensor readings into ppm values. The system performed effectively within the 0–8 ppm range and was validated against a commercial ammonia test kit. Despite minor errors caused by sensor warm-up time and vapour leakage, the system offers an affordable and practical solution for aquaculture, environmental monitoring, and educational applications, with potential for future IoT-based remote monitoring.