A Low-Cost IoT-Enabled Intelligent Greywater Treatment System with Adaptive Re-Filtration Control for Decentralized Urban Water Reuse

Abstract

With increasing urbanization and water shortages, decentralized sustainable systems for wastewater management are needed more than ever. Greywater makes up 50-80% of residential wastewater and can be easily treated because it does not require treatment to the standards of potable water. However, many treatment systems are overly expensive, overly energy consuming, or are void of smart automation. Here, we present a cost-effective, Internet of Things (IoT) based automated greywater treatment system with multiple stages of physical filtration coupled with adsorption, ultraviolet (UV) disinfection, aeration polishing, and an adaptive re-filtration feedback control. The system uses the ESP32 microcontroller to monitor the quality of water based on turbidity, pH, TDS, flow, and level in real time, and subsequently controls the operations of the treatment system, including the pumps, UV and aeration devices. An algorithm based on a quality control standard recirculates water for treatment if it does not meet the requirements. Results from tests conducted show that the treated water meets the standards of non-potable water reuse set by WHO and BIS, with a BOD level of less than 30 mg/L with an >90% removal, turbidity removal of >93% and TSS removal of >85%. The automated treatment system is designed to treat water on a daily basis. The system is also designed to be scalable and affordable, with a projected daily energy consumption of 40-60 Wh, and a hardware cost of approximately ₹8,500-9,200 (USD 100-110).