Water Journal : Water Journal April 2014
WATER APRIL 2014 60 Feature Article INTRODUCTION Water quality monitoring is an important part of water management and there are many examples of technical challenges throughout the water cycle from catchment to tap. The application of online monitoring and associated sensors will contribute to several key areas of the water business. Changing environmental conditions mean that the quality of source waters is showing increased variability, and early detection of changes in quality and impacts on the treatment process is vital. In drinking water quality management, any perturbations from the norm in the water treatment process or in distribution systems need to be identi ed and located quickly, thus minimising water quality incidents and customer inconvenience. Then, in the wastewater area, there is constant pressure to improve the ef cacy of processes, especially for the removal of nutrients and other key contaminants to meet increasingly stringent disposal guidelines. Another factor that can adversely impact on the wastewater treatment process is shock loads of contaminants such as trade wastes. Online monitoring has the potential to give a rapid indication of the changing quality of wastewater and will allow improved management methods to be adopted. Monitoring the quality of treated wastewater will minimise the risk of environmental incidents. Rapid responses to problems within water and wastewater systems will minimise the costs associated with the corrective actions. With stormwater, the raw product is known to be highly variable and many schemes are designed to allow separation of " rst- ush" water prior to treatment from the main body of the treatment system. However, such procedures are far from optimised and, by the time laboratory analysis is carried out and data con rmed, stormwater that is potentially of good quality and high value can be wasted. Similar concerns reveal a growing need for the development of online sensors for water and wastewater areas of the industry. This report is based on the outcomes of the Ozwater'13 Online Water Quality Monitoring Workshop presented by the AWA Water Quality Monitoring and Analysis Specialist Network with the contribution of the Water Environment Research Foundation 'Compendium of Sensors and Monitors and Their Use in the Global Water Industry'. We present the view from the water industry as end user, and with engineering consultancy companies and university research teams as service providers. Four key discussion topics: 1) Instrument Selection; 2) Equipment Issues; 3) Data Transfer and Management; and 4) Key Challenges in Implementation -- Drivers and Bene ts, were pre-selected based on the outcomes of the International Conference on Intelligent Sensors, Sensor Networks and Information Processing Water Quality Monitoring Workshop 2011. 1. Instrument Selection Treatment Performance Indicators (TPIs) were found to be the key criteria to support the correct instrument selection and for developing a successful business case for capital spending. A list of key water quality parameters that are currently measured and a participant "wish list" captured from the workshop discussion are presented in Table 1. Several sensing parameters that can be directly used as TPIs are process dependent. The parameters presented are categorised into physical/particles, chemical, biological and unusual/novel parameters with indication of whether they can be used as direct TPI (bold text) or as a surrogate. The success of the application will be dependent on the selection of a suitable sensor/instrument for the task; it is especially important to consider the sample, as it was reported by some attendees that quite often problems are caused by incorrect use of a sensor in an inappropriate sample. For the particle/physical category, particle counter, turbidity, particle charge analyser, streaming current detector and conductivity are listed. Turbidity is the most commonly used parameter and turbidity meter selection is quite important when considering the water type/quality. Both turbidity and conductivity are direct TPIs, ONLINE WATER QUALITY MONITORING: THE VOICE OF EXPERIENCE Quality monitoring is a vital part of water management, however, it's not without its technical challenges. This report is based on the outcomes of the Online Water Quality Monitoring Workshop that took place at last year's Ozwater Conference & Exhibition in Perth. Table 1. Water quality parameters -- currently measured and desired. Particles/physical Chemical Biological Novel Particle counter pH Chlorophyll-a EIS Turbidity Chlorine/chloramine Phycocyanin 3D Fluorescence EEM Particle Charge Analyser UV absorbance Coal seam gas monitoring Streaming current TOC Sulphate Conductivity Colour Disinfection by-products Coagulant residual (Fe/Al) PAH DO Phosphate Note: Bold Text -- directly used as TPIs.
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