Solar-Powered Mobile Sensing System Integrated with LoRa and IoT for Real-Time Domestic Wastewater Quality Monitoring

Abstract

Domestic wastewater treatment plants (DWTPs) must keep pond effluent within Indonesia's mandated wastewater quality standards, yet most operators still rely on manual, edge-of-pond sampling, which is slow, labour-intensive, and cannot represent the whole pond surface. This study develops a solar-powered, remotely controlled mobile sensing platform integrated with Long Range (LoRa) communication and Internet of Things (IoT) connectivity for real-time domestic wastewater quality monitoring. The system comprises a Mobile System that floats on the pond, carrying temperature, pH, TDS, turbidity, and dissolved oxygen (DO) sensors with a solar panel, battery, and two DC-motor thrusters, and a Monitoring System at the pond edge that relays sensor data via LoRa to an LCD and the ThingSpeak platform, and issues four-directional motion commands to the Mobile System through a second LoRa link. The fabricated prototype was validated experimentally: against laboratory references (n = 30 per sensor), the five sensors achieved R² = 0.9654–0.9942 with MAPE below 5%; the dual LoRa links held packet loss below 4% up to 250 m line-of-sight; the ThingSpeak link achieved 98.92% data-delivery success with 1.35 s average latency over a 72-hour test; and the solar system supplied a daily surplus of 412 Wh against 152.7 Wh consumed, keeping battery charge above 81.5% throughout. This work contributes a mobile, solar-powered, LoRa- and IoT-integrated monitoring architecture, experimentally validated at prototype scale, enabling operators to obtain water quality data across the pond surface and redeploy the platform across multiple ponds without additional cabling.