Guidelines for Drinking-Water Quality

Introduction Abundance and quality water supply is essential for all living species. Sustainable agriculture and industrial production need steady supply of freshwater. In many parts of the today’s world, desalination plays a vital role for sustaining human habitation besides the existing conventional water treatment technologies. Membrane based RO process has become a popular method to supply the fresh water from seawater and brackish water in different regions. RO (Figure 1) is a pressure driven process which under pressure reverses the flow direction of the solvent (in the opposite direction of osmosis process). Substantial efforts have been made by researchers on freshwater production (Sassi, 2012) and wastewater treatment (Stoller et al., 2016) using the RO. Rapid growth of membrane desalination processes enhanced the removal of ionic contaminants (Sassi and Mujtaba, 2013), pharmaceutical active compounds (Gur-Reznik et al., 2011) and other types of effluents from chemical, petrochemical, electrochemical, food, paper and tanning industries. Demineralised water can be supplied to several industries by treating the saline water using the RO process. However, there are limited studies on the production of demineralised water. Demineralised water is completely free (or almost) of dissolved minerals (Kremser et al. 2006) which has total dissolved solids (TDS) as low as 1 mg/l. Kremser et al. (2006) described operating experience on demineralized water plant. In this work, RO based desalination process is considered using three stages described by (Sassi, 2012) as shown in Figure 1. The plant nominal operating and design parameters (of commercial Film Tec spiral wound RO membrane elements) are taken from Abbas (2005). Firstly, the model prediction is validated against those reported by Sassi and Mujtaba (2010). Secondly, an optimization problem incorporating a process model is formulated to optimize the design and operating parameters in order to minimize specific energy consumption and the results are compared with Sassi (2012). Since those models (Sassi, 2012) are validated for freshwater production, the model parameters such as (water and salt permeability coefficients) needs to be updated for demineralised water. A structure of the RO network is developed based on RO network (two-stage seawater pass and two-stage brackish water pass). Different parameters are updated for the model from the literature.

Maybe, the first question that we have to ask ourselves is related to the decision of an adsorprtion process using activated carbon for the removal of micro pollutants is efficient. The theory says that the adsorbability of an organic molecule increases with increasing molecular weight and decreasing solubility and polarity. This means that high molecular weight compounds with low solubility, such as most pesticides, are well adsorbed, so the first idea is plenty justified.

Introduction The purpose of producing this handbook is to provide basic information and guidelines for the implementation of good shaft alignment, vibration analysis and dynamic balancing practice for standard rotating machines systems. Laser alignment, dynamic balancing and condition monitoring are essential components of a viable maintenance strategy for rotating machines. In isolation each strategy helps to reduce unexpected machine failure but taken together they form the hub of a proactive maintenance strategy that will not only identify incipient problems but will extend machine operating life considerably. In each section of this handbook we have used one or two examples of the available methods for measuring the required parameters. We do not suggest that the methods illustrated are the only ones available. For anyone wishing to pursue further the subjects covered here a bibliography of some of the available literature is to be found at the end of this handbook.