In-pipe water quality monitoring in water supply systems under steady and unsteady state flow conditions: a quantitative assessment

Monitoring the quality of drinking water from the treatment plant to the consumers tap is critical to ensure compliance with national standards and/or WHO guideline levels. There are a number of processes and factors affecting the water quality during transmission and distribution which are little understood. A significant obstacle for gaining a detailed knowledge of various physical and chemical processes and the effect of the hydraulic conditions on the water quality deterioration within water supply systems is the lack of reliable and low-cost (both capital and O & M) water quality sensors for continuous monitoring. This paper has two objectives. The first one is to present a detailed evaluation of the performance of a novel in-pipe multi-parameter sensor probe for reagent- and membrane-free continuous water quality monitoring in water supply systems. The second objective is to describe the results from experimental research which was conducted to acquire continuous water quality and high-frequency hydraulic data for the quantitative assessment of the water quality changes occurring under steady and unsteady-state flow conditions. The laboratory and field evaluation of the multi-parameter sensor probe showed that the sensors have a rapid dynamic response, average repeatability and unreliable accuracy. The uncertainties in the sensor data present significant challenges for the analysis and interpretation of the acquired data and their use for water quality modelling, decision support and control in operational systems. Notwithstanding these uncertainties, the unique data sets acquired from transmission and distribution systems demonstrated the deleterious effect of unsteady state flow conditions on various water quality parameters. These studies demonstrate: (i) the significant impact of the unsteady-state hydraulic conditions on the disinfectant residual, turbidity and colour caused by the re-suspension of sediments, scouring of biofilms and tubercles from the pipe and increased mixing, and the need for further experimental research to investigate these interactions; (ii) important advances in sensor technologies which provide unique opportunities to study both the dynamic hydraulic conditions and water quality changes in operational systems. The research in these two areas is critical to better understand and manage the water quality deterioration in ageing water transmission and distribution systems.     

Some Recent Developments on the Effects of Parameter Estimation on Control Charts

Statistical process control plays a key role in today's highly competitive industrial environment since it allows quality practitioners to timely detect out‐of‐control situations and take actions whenever necessary in order to ensure that the products or services produced correspond to certain quality standards. Control charts are the tools quality practitioners use, and their monitoring performance is of major importance in practical applications. Since the values of the parameters used for the design of the charts' control limits are usually unknown in practice, the practitioners need to estimate them using an in‐control retrospective sample. It has been shown that parameter estimation severely affects the control charts' properties. Many recent studies focused on investigating the impact of parameter estimates on the performance of control charts and on ways of diminishing this impact. This paper aims to provide an up‐to‐date critical review on the methodologies that have recently been developed in this area. Copyright © 2013 John Wiley & Sons, Ltd.     

Towards a framework for energy-aware information systems in manufacturing

Environmental concerns, stricter legislation and inflated energy costs, together yield energy efficiency as an important pillar for virtually every industrial sector. Mindful of this challenge, ISs can act as enablers of energy-based management and intelligent decision support. Based on empirical evidence through two case studies combined with the design of a system prototype, this paper identifies those major functionalities that suffice to characterize an IS as ‘energy-aware’ in manufacturing. The functionalities are classified into two broad categories: (a) energy monitoring and (b) energy-aware analytics and are then combined into a high-level architecture. As a prerequisite for deploying such functionalities, this research presents also an approach integrating energy and operational information flows. Beyond that, the technologies that support the real-time and large-scale handling of energy data are provided. Our effort scales up to introduce a generic framework of a case-independent energy-aware IS.     

New waste-based clinkers for the preparation of low-energy cements. A step forward toward circular economy

This paper describes the use of industrial wastes arising from different production processes of the ceramic and marble industries as raw materials for the design and formulation of new cement clinkers with a high content of dicalcium silicate (Belite). The aim was to reintroduce these wastes in the industrial sector and take advantage of them for a greater environmental benefit, as indicated by the principles of the circular economy. Formulations containing 2.5, 5 and 10 wt% of chamotte and marble sludge, respectively, and a waste-free formulation have been designed to obtain clinkers with a content of dicalcium silicate higher than 60 wt%. The different blends have been studied up to a maximum temperature of 1390°C by Thermal Analysis. Other techniques such as XRD, XRF, Modified Bogue Equation, Quality Indexes (LSF, AM, SM) and Optical Microscopy have been used for the study and characterization of industrial wastes, the raw materials and the high belite-type cement dosages. The results indicate that this type of cements can be designed using different types of wastes and in this way reduce the environmental impacts caused by the extraction of raw materials and the deposition of the wastes in landfills, improving the circular economy of the construction industry.     

Removal of heavy metals from wastewater using CFB-coal fly ash zeolitic materials

Polish bituminous (PB) and South African (SA) coal fly ash (FA) samples, derived from pilot-scale circulated fluidized bed (CFB) combustion facilities, were utilized as raw materials for the synthesis of zeolitic products. The two FAs underwent a hydrothermal activation with 1 M NaOH solution. Two different FA/NaOH solution/ratios (50, 100 g/L) were applied for each sample and several zeolitic materials were formed. The experimental products were characterized by means of X-ray diffraction (XRD) and energy dispersive X-ray coupled–scanning electron microscope (EDX/SEM), while X-ray fluorescence (XRF) was applied for the determination of their chemical composition. The zeolitic products were also evaluated in terms of their cation exchange capacity (CEC), specific surface area (SSA), specific gravity (SG), particle size distribution (PSD), pH and the range of their micro- and macroporosity. Afterwards the hybrid materials were tested for their ability of adsorbing Cr, Pb, Ni, Cu, Cd and Zn from contaminated liquids. Main parameters for the precipitation of the heavy metals, as it was concluded from the experimental results, are the mineralogical composition of the initial fly ashes, as well as the type and the amount of the produced zeolite and specifically the mechanism by which the metals ions are hold on the substrate.     

Occurrence, virulence genes and antibiotic resistance of Escherichia coli O157 isolated from raw bovine, caprine and ovine milk in Greece

The examination of 2005 raw bovine (n = 950), caprine (n = 460) and ovine (n = 595) bulk milk samples collected throughout several regions in Greece for the presence of Escherichia coli serogroup O157 resulted in the isolation of 29 strains (1.4%) of which 21 were isolated from bovine (2.2%), 3 from caprine (0.7%) and 5 from ovine (0.8%) milk. Out of the 29 E. coli O157 isolates, only 12 (41.4%) could be classified as Shiga-toxigenic based on immunoassay and PCR results. All 12 Shiga-toxigenic E. coli serogroup O157 isolates belonged to the E. coli O157:H7 serotype. All except one of the 12 Shiga-toxin positive isolates were stx₂-positive, five of which were also stx₁-positive. The remaining isolate was positive only for the stx₁ gene. All stx-positive isolates (whether positive for stx₁, stx₂ or stx₁ and stx₂) were also PCR-positive for the eae and ehxA genes. The remaining 17 E. coli O157 isolates (58.6%) were negative for the presence of the H7 flagellar gene by PCR, tested negative for Shiga-toxin production both by immunoassay and PCR, and among these, only four and three strains were PCR-positive for the eae and ehxA genes, respectively. All 29 E. coli O157 isolates displayed resistance to a wide range of antimicrobials, with the stx-positive isolates being, on average, resistant to a higher number of antibiotics than those which were stx-negative.     

A sum of squares triple exponentially weighted moving average control chart

Control charts are widely known quality tools used to detect and control industrial process deviations in statistical process control. In the current paper, we propose a new single memory-type control chart, called the sum of squares triple exponentially weighted moving average control chart (referred as SS-TEWMA chart), that simultaneously detects shifts in the process mean and/or process dispersion. The run length performance of the proposed SS-TEWMA control chart is compared with that of the sum of squares EWMA, sum of squares double EWMA, sum of squares generally weighted moving average, and sum of squares double generally weighted moving average, control charts, through Monte Carlo simulations. The comparisons indicate that the proposed chart is more efficient, than the competing ones, in detecting small shifts in the process mean and/or variability for most of the considered scenarios, while it has comparable performance for some others in identifying large shifts in the process mean and small to large shifts in the process variability. Finally, two illustrative examples are provided to explain the application of the SS-TEWMA control chart.     

Superhydrophobic,passive microvalves with controllable opening threshold: exploiting plasma nanotextured microfluidics for a programmable flow switchboard

Plasma processing is used to create passive superhydrophobic on–off valves with tailored opening pressure inside microfluidic devices. First, anisotropic O₂ plasma etching on polymeric microchannels is utilized to controllably roughen (nanotexture) the bottom of the microchannel. Second, the nanotextured surfaces are hydrophobized by means of a C₄F₈ plasma deposition step through a stencil mask creating superhydrophobic stripes or patches. The superhydrophobic patches play the role of on/off valves with predesigned opening pressure threshold (in the range 40–110 mbar), determined by the microchannel dimensions and the size of the nanotexture on the patch. These valves are integrated inside microchannel networks paving the way to autonomous microfluidic devices. To this aim, we present a novel preprogrammable flow switchboard that can split and control the liquid flow for multiple analysis purposes. The proposed valves present an example of how effectively plasma nanoscience and nanotechnology can be applied to microfluidics/nanofluidics and analytical chemistry.