Sewerage system monitoring based on Wireless Sensor Network

by Lue Ik Hong and Dr Wong Kiing Ing
                                                                                      

A team of researchers at Curtin University, Sarawak Malaysia (Curtin Sarawak) just might have the breakthrough high-tech solution to effectively monitoring sewerage systems in Sarawak, an area where research and development has been lacking until now.

Its Wastewater Management System for Kuching City Centre Project was approved in 2008 under the Ninth Malaysia Plan (9MP) and is expected to be completed in the next four years.

The sanitary sewer will be used to transport black water from toilets and grey water from bathrooms, kitchen and washing areas to a centralised wastewater treatment plant for effective processing before being discharged into the environment.

Inflow and infiltration are used to describe the events where storm water and groundwater, respectively, enter the sanitary sewer system. Overflow occurs when there are blockages, significant inflow or infiltration in the collection system, or its capacity is inadequate for collection, storage or treatment. This problem is commonly referred to as sanitary sewer overflow (SSO), which is unique to sanitary sewers because their pipe sizes are designed to carry only sanitary water.

The various sources that contribute to SSO are very hard to detect in the early stages. For instance, drains that are improperly and illegally connected to the sanitary sewer system, as well as cracks and leaks caused by aging processing and maintenance errors are some of the factors that contribute to inflow and infiltration. SSO poses costs and health risks, including burdening the central treatment plant, flooding in households and traffic congestion.

Managing a sewerage system is a difficult task because everything about a sewerage system, except failure, is invisible. The challenge for the industry is to bring visibility to the events that reduce capacity and increase flow before one or both can result in outright failure.

A sewer is considered to have failed when certain events become visible, such as a basement flooding, a roadway collapsing, or when SSO occurs, in which any action taken afterwards is considered pointless. Therefore, an effective sewerage monitoring system is needed to detect any abnormal changes and decide the appropriate action to be taken before a disaster happens.

Up until now, where research is concerned, there has been little effort put into designing a remote, real-time sewerage system monitoring tool. However, advancements in the fields of micro-electronic and computing technologies have made real-time sewerage environment sensing and monitoring possible.

The Wireless Sensor Network based monitoring system developed at Curtin Sarawak is a prototype monitoring system that detects sewerage problems and provides accurate flow-monitoring data combined with appropriate analysis in real-time.

It consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, and to cooperatively transfer the data through the network to a main location.

‘Real-time’ is defined here as the important information captured in the field and periodically interpreted in the control room, either by the minute, hour, or daily. The information provides a decision-support system (DSS) for delivering insight into possible actions to be taken, for example, taking efficient operation and proactive measures and management of sewerage pipeline networks.

It can also help reduce leakages and breakages of water distribution pipes, and may also mitigate damage due to sewer backup, collapse, blockages, excessive infiltration or inflow, and flooding.

Engineers, scientists and biologists can use the data and relate it to the impact of pollutants on the environment, as well as look into methods and strategies to generate a sustainable environment.

Project Development at Curtin Sarawak

The technology development for the project is in the early prototyping stage. The project is expected to be completed in a year’s time. In the meantime, we remain in close contact with the Sewerage Services Department, Sarawak, which provides us technical advice on sewerage systems and updates on technology development.

TinyOS (Tiny Operating System) will be used for the software design of wireless sensor, avoiding the traditional embedded software design based on the assembly, C, C++ or Java language. TinyOS is able to generate very efficient code for resource-constrained devices, such as our sensor node which has very limited memory features, and provides very extensive wireless networking capabilities.

A gateway will be designed and fabricated to relay the data to a central control room. The gateway will be a single board computer running on real-time embedded Linux that supports TinyOS protocols, Bluetooth, General Packet Radio Service (GPRS) access and direct connection with central control room. TinyOS protocols and Bluetooth will be used by the wireless sewer sensor and on-site handheld device communications, respectively.

The collected data will be relayed directly to the central control room for data management and analysis. The relay nodes and gateway will be installed on lamp poles in the city and the modules will be powered by both rechargeable batteries and solar panels.

A central control system will be set up for data gathering, storage and further analysis. A complex simulation model of the sewer system will be investigated, including a linear quadratic or model predictive control method to address the constraints of wireless sewer sensors and location. These decision-support tools will be used for data interpretation and analysis, and support operations and maintenance decisions.

Wireless sensing architecture for Underground Sewerage Pipeline.

Lue Ik Hong is a research assistant at Curtin Sarawak, undertaking research on ‘Sewerage Sanitary Overflow Telemetry System Based on Wireless Sensor Network’. He is currently pursuing a Master of Philosophy at the university and is expected to graduate in 2013. His research interests include wireless sensor networks, ultra-wideband technology and embedded systems. He can be contacted by e-mail at lueikhong@gmail.com.

Dr Wong Kiing Ing is a senior lecturer of Electrical and Computer Engineering at the School of Engineering and Science at Curtin Sarawak. He received his B.Eng. (Hons.) and Ph.D. degrees in electrical engineering from the University of Manchester in 1999 and the University of Southampton in 2004, respectively. His research interests include biomedicine instrument, wireless sensor, and intelligent environment monitoring and control. His research has attracted funding from the Ministry of Science, Technology and Innovation (MOSTI), Malaysia. He can be contacted by e-mail at wong.kiing.ing@curtin.edu.my

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