Sustainable water use in chemical, paper, textile and food industries
This report is a result of the project AquaFit4Use, a large-scale European research project cofinanced by the 7th framework programme of the European Union on water treatment technologies and processes. This report highlights the results of two additional studies: • The evaluation of water quality sensors and analyzers in order to measure the quality of water in industrial processes, particularly in case of reuse. • The development of software in order to manage effectively on-line and off-line measurements and specifics modules in order to get high-content information concerning the state of the process. The first task was to develop a test protocol in order to define criteria of comparison to evaluate sensors. This test protocol allows calculating comparison criteria to benchmark the instruments. In such a project as Aquafit4Use one, where the water quality is one of the main concerns, sensors can stand as a key for many studies (simulation, efficiency of new processes…). Four parameters were chosen to describe water quality among the list established in WP 1.1. Lab-scale tests on substitute waste waters (synthetic samples) are thus performed for: • 5 Chemical Oxygen Demand (COD) sensors and analyzers, • 1 Total Nitrogen (Total N) analyzer, • 2 Orthophosphate (PO43-) analyzers, • 2 Calcium (Ca) sensors. The tests were executed according to the protocol built in the WP 2.1 and the devices are evaluated and compared by the aid of common criteria about static (accuracies) and dynamic (response times) characteristics. At lab-scale, the instruments based on physical UV absorption are the only devices that meet all the requirements set in the preliminary study for COD measurement. The other devices use more complicated measurement principle based on full spectrum absorption (Spectro::Lyser from S::CAN and CarboVis from WTW) or chemical reactions (PeCOD P100 from aqua Diagnostic) that induce more important data treatments. Pilot-scale tests are also executed on the COD and Orthophosphate sensors and analyzers in order to evaluate the devices in conditions closer to real operating conditions. The results remain poorer than the lab-scale tests because of the real and complex water matrix. Nevertheless, one analyzer gives quite good results given that its calibration overcomes the water matrix. In a later stage of the project, industrial tests should be executed to complete the evaluation and comparison. Regarding the data processing software, the interface is developed and tested. This decision support tool aims to improve the user information levels. The architecture used with high level of modularity allows further developments of modules. One module was implemented to make classification and data reconciliation. The method chosen allows making reliable the information brought by measurements and to determine the current state of the process. Moreover, four pretreatments were implemented to detect sensors faults. A case study was achieved to illustrate the results. At last, a remote access tools was added to the software in order to provide remote web access to the high-level information module software.