C.J. Brouckaert

The reuse of reactive dye liquors using charged ultrafiltration membrane technology

A closed-loop recycle system using a charged ultrafiltration membrane to decolourise reactive dye effluents from a textile yarn and fabric dyeing process is described. The economics of the process depend on the value of the electrolyte (

Modelling of nanofiltration applied to the recovery of salt from waste brine at a sugar decolourisation plant

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A new general methodology for incorporating physico-chemical transformations into multi-phase wastewater treatment process models

10 per M3). Conventional reactive dyeing technology was examined and modified to facilitate dye liquor reuse. The performance of the membrane was examined in terms of electrolyte rejection, colour rejection and permeate flux under varying conditions of solution pH, ionic strength and operating pressure.

Leak identification in a water distribution network using sparse flow measurements

Abstract The implementation of a computer model to simulate reverse osmosis in systems with several components is described. The model was based on the Spiegler-Kedem theory of reverse osmosis. The results of a pilot-scale investigation of the use of nanofiltration to recover sodium chloride from waste brine from the regeneration of anion exchange resin were used in this study. This effluent contains around 50 g/l of sodium chloride and 5 g/l (as total carbon) of organic colourants, many of which are negatively charged. When using the SelRO TM MPT-30 or MPT-31 membrane at an operating pressure of 3 MPa, temperatures between 45°C and 60°C, and linear feed flow rates around 1.6 m/s, the retention of sodium chloride was found to be between 0% and 20%, while the organic compounds had an overall retention of 80% to 97%. The experimental results were used to obtain a set of parameters relating to the system, which were then used to generate design data for a full-scale plant. Suitable module arrangements were proposed and the system performance for each case was predicted.

Criteria for selecting the operating regime of the crossflow microfilter or the tubular filter press for clarification of turbid waters

This paper introduces a new general methodology for incorporating physico-chemical and chemical transformations into multi-phase wastewater treatment process models in a systematic and rigorous way under a Plant-Wide modelling (PWM) framework. The methodology presented in this paper requires the selection of the relevant biochemical, chemical and physico-chemical transformations taking place and the definition of the mass transport for the co-existing phases. As an example a mathematical model has been constructed to describe a system for biological COD, nitrogen and phosphorus removal, liquid-gas transfer, precipitation processes, and chemical reactions. The capability of the model has been tested by comparing simulated and experimental results for a nutrient removal system with sludge digestion. Finally, a scenario analysis has been undertaken to show the potential of the obtained mathematical model to study phosphorus recovery.

The Use of Energy‐Dispersive X‐Ray Microanalysis as a Rapid Method for Demarcating Areas Around Marine Outfalls that may be Influenced by Effluent: A Case Study

Abstract A linear programming technique is proposed to balance the flows in a network, matching flow measurements where available. Where necessary, a “leak-out” flow is invoked on a pipe section in order to achieve the balance. Usually, multiple solutions are possible, and these are sounded out by progressively increasing an integrity weight for each pipe section. A feature of the method is that it overlays “snapshots” of the network at a series of points in time, in order to progressively narrow down the part of the network which can commonly account for all observations.

Predicted performance profiles along a long-tube cross-flow microfiltration system

Abstract The EXXFLOW crossflow microfilter (CFMF) and the EXXPRESS tubular filter press (TFP) are potential choices for the clarification of turbid waters. Both processes use a woven fabric support in the form of a horizontal array of tubes. The TFP is a limiting case of the CFMF as the crossflow velocity tends to zero. Previously, it has not been considered as an alternative to the CFMF to clarify turbid waters, but has been used to dewater concentrated suspensions to produce spadeable cakes. The TFP will have lower pumping costs associated due to its operation in the lower velocity regime. Experimental work was conducted on woven tubes using a bentonite and kaolin suspension over the concentration range 75 to 600 mg/l to obtain flux and turbidity data. It was found that the TFP and the CFMF were able to produce a permeate with a turbidity less than 0.5 NTU. However, the TFP had to be precoated with a 300 mg/l suspension of limestone in a crossflow mode prior to switching to the dead-end mode. The design procedure for choosing the most economic mode of operation is outlined, although experimental investigations of the CFMF and the TFP are not yet sufficiently complete to provide all the data necessary for a fully justified economic choice under all circumstances. The experimental results to date show that for low solids concentrations in the feed (75 to 150 mg/l), operation in the dead-end mode (TFP) is more favourable with respect to filtration area and pumping power, whereas the the higher concentrations (300 to 600 mg/l) the CFMF is able to reduce the area requirement at the expense of greater pumping costs.

Optimal operation of water distribution networks by predictive control using MINLP

Abstract Surveys that monitor pollution in a marine environment often include the measurement of heavy metals and other trace elements in sediments obtained from multiple stations near marine outfalls. This study investigates the use of energy‐dispersive x‐ray (EDX) microanalysis as a rapid screening method, where characteristic or “signature” elements (SE) in effluent can be located and mapped on the seabed. Thereafter, sediments from stations/areas with high SE can be examined using more sensitive spectroscopic methods, and, if present, trace metals quantified. To serve as controls, 21 samples of sediment were obtained from two “pristine” areas off the Kwazulu Natal coast. A further 99 samples were obtained from stations within 2 km of the Huntsman Tioxide pipeline. Each sample was sonicated to separate the coarse from fine fractions. The fines were collected on a paper filter and mounted next to its corresponding, washed, coarse fraction on a graphite stub. Each sample was coated with C and examined by EDX. Huntsman Tioxide effluent was rich in Ti and Fe. The fine and coarse fractions of all sediments were screened for these elements. A contamination index (I) was constructed from the combined fines, Ti and Fe data. Surfer 16 software was employed to create contour plots showing the distribution of Ti, Fe, and I in fine and Ti in coarse fractions of sediments near the Huntsman Tioxide pipeline. The results showed that EDX was an effective method for locating fallout “hot spots” and delimiting an area affected by effluent. #This paper was by special invitation as a contribution to a special issue of the journal entitled “Application of Spectroscopic Methods to Environmental Problems.” The special issue was organized by Professor Peter A. Tanner, Professor in the Department of Biology and Chemistry at City University of Hong Kong.

The Use of Computational Fluid Dynamics for Improving the Design and Operation of Water and Wastewater Treatment Plants

Abstract In cross-flow microfiltration (CFMF) tubes where a significant change in pressure, concentration and flow rate occurs along the tube, the cake thickness and permeate flux may also change along the length of the tube. In this paper, an attempt is made to ascertain the trends that cake thickness and permeate flux are likely to exhibit in a long tube, based on the integration of the Hunt model for short tube elements. Seemingly anomalous results are explained and validated in terms of a generalised phenomenological model for CFMF. It is found that the cake thickness can increase or decrease along the tube, depending on the inlet conditions to the system. In principle, it is feasible to choose operating conditions that would result in a constant cake thickness along the tube, thereby avoiding the probability of tube blockage or changing permeate quality. The average flux for a tube is considerably lower than the point flux at the inlet end of the tube. Thus any attempt to calculate the permeate production rate by using only the inlet operation conditions is likely to lead to an error in design.