Showing papers in "Desalination and Water Treatment in 2011"

Erratum to Thermophysical properties of seawater: A review of existing correlations and data

Abstract: (2011). Erratum to Thermophysical properties of seawater: A review of existing correlations and data. Desalination and Water Treatment: Vol. 29, No. 1-3, pp. 355-355.

Energy consumption and recovery in reverse osmosis

Abstract: Energy consumption is a key factor which influences the freshwater production cost in reverse osmosis (RO) process. Energy recovery and reuse options have already been very well explored in the current desalination industry. Achieving minimum theoretical specific energy consumption for water recovery is not feasible due to effects of concentration polarization, membrane fouling and hydraulic resistance to permeate flow. Due to these limitations, energy recovery along with water recovery can be a better alternative to improve energy consumption and economics of the RO process both in small and large scale applications. This paper reviews currently available process configurations, operating strategies, and discusses potential pathways to recover and recycle energy and water to improve the performance of the RO process.

Nutrient removal from aquaculture wastewater by vegetable production in aquaponics recirculation system

Abstract: Nutrient removal is essential for aquaculture wastewater treatment to protect receiving water from eutrophication and for potential reuse of the treated water. The integration of aquaculture with agriculture appears to be an excellent way of saving water, disposing aquaculture wastewater and providing fertilizer to the agricultural crop. The study was conducted to evaluate aquaponics recirculation system (ARS) performance in removing inorganic nitrogen and phosphate from aquaculture wastewater using water spinach (Ipomoea aquatica) and mustard green (Brassica juncea). The results showed that water spinach was able to significantly reduce the total ammonia nitrogen, nitrite-N, nitrate-N and orthophosphate with efficiencies of 78.32–85.48%, 82.93–92.22%, 79.17–87.10%, and 75.36–84.94%, respectively, compared to mustard green that removed the nutrients in the range of 69.0–75.85% for total ammonia nitrogen, 72.49–79.34% for nitrite-N, 66.67–80.65% for nitrate-N, and 66.79–77.87% for orthophosphate. Overall r...

Treatment of coal seam gas produced water for beneficial use in Australia: A review of best practices

Abstract: There has been an exponential increase in both the production and exploration of coal seam gas (CSG) in Australia and many other regions in the world. A major issue associated with the production of CSG is the management of produced water. CSG is usually mixed with water in the coal seam, to recover the gas, the water must be first extracted from the coal seam to reduce pressure. This water — known as co-produced water or CSG water — is typically quite saline, large in volume and may contain heavy metals and other trace elements of concern. The management of this produced water is of paramount importance to the oil and gas industry. This paper reviews the key characteristics of CSG water and its possible beneficial uses. A specific focus is on the role of reverse osmosis (RO) membranes in the treatment of produced water for beneficial uses or safe discharge into the environment. Recent examples involving the use of RO membranes for the treatment of produced water are systematically summarised and discusse...

Ferrate(VI): In situ generation and water treatment – A review

Abstract: Over the past few years, the higher oxidation states of iron (ferrate, Fe(VI)) are of interest because of their involvement in reactions of environmental, industrial, and biological importance. New ferrate chemistry is still being developed and new analytical techniques are used to characterise the ferrate species. Applications of ferrate to treat common pollutants and emerging contaminants such as arsenic, estrogens, pharmaceuticals, and personal-care products are being explored. Ferrate is emerging as a green chemical for organic synthesis and for treating toxins in water. This review paper aims to discuss the potential of generating ferrate(VI) in situ and using it for water treatment. The first part provides a short review of recent advances in Fe(VI) synthesis and introduces its in situ electrochemical synthesis. The second part is devoted to application of Fe(VI) in the treatment of water as an oxidant, disinfectant and coagulant. Since iron is required as a growth factor by humans, normally innocuo...

Preparation of high-flux thin film nanocomposite reverse osmosis membranes by incorporating functionalized multi-walled carbon nanotubes

Abstract: To enhance the water flux of reverse osmosis membranes, thin film nanocomposite reverse osmosis membranes are prepared by incorporating functionalized multi-walled carbon nanotubes (MWNTs). The functionalized MWNTs are obtained by the treatment of pristine MWNTs with the mixed acid of H2SO4 and HNO3 (3:1 v/v). The MWNTs are analyzed by Fourier transform infrared spectrometry (FTIR). The surface morphology and structure of membrane are characterized by scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and contact angle measurement, respectively. Those results show that modified MWNTs yielded some hydrophilic groups, such as -COOH and -OH, which make acidified MWNTs disperse more evenly in the aqueous solution. The SEM and TEM results demonstrate that the functionalized MWNTs penetrated through the polyamide layer, and might play the role of water channel. Compared with the bare polyamide membrane, the MWNT-polyamide thin film nanocomposite membranes have more hydrophilic surface,...

A review of electrocoagulation as a promising coagulation process for improved organic and inorganic matters removal by electrophoresis and electroflotation

Abstract: In drinking water treatment, coagulation is the most common process to remove particles and impurities. It is described as the process whereby particles are destabilised by dosing a chemical additive (coagulant) where charge neutralisation (CN) and sweep coagulation (SC) are the major mechanisms. Due to the encountered difficulties in natural organic matter (NOM) removal, the concept of enhanced coagulation (EnC) was introduced to increase NOM removal where CN is more accentuated. EnC must be well optimised to overcome its practical considerations such as adjusting the pH of the source water and residual metal concentration in the treated water. In the last three decades, there is new tendency to use electric field/electrochemistry in some chemical processes especially chemical coagulation (CC). Indeed, literature has proved that electrocoagulation (EC) is a promising water treatment technology. During EC process, there are two induced phenomena: electrophoresis (EP) and electroflotation (EF); separately,...

Research articles published in water resources journals: A bibliometric analysis

Abstract: This study was designed to evaluate the global scientifi c output in the ISI subject category of “water resources” for the past 16 years. Data were based on the online version of the Science Citation Index Expanded, Web of Science, from 1993 to 2008. Articles referring to water resources were assessed for many aspects, including distributions of source countries, institutes, words in the title, author keywords, and KeyWords Plus. The h-index was also calculated in terms of the characteristics of publications. Distributions of paper titles, the author’s

Closed circuit desalination — A new low energy high recovery technology without energy recovery

Abstract: Closed circuit desalination of Mediterranean water with 475±15% recovery was demonstrated in the RO energy range 185–225 kWh/m 3 for the respective flux range 6–18 lmh with head element recovery of 70±05%

Photovoltaic reverse osmosis — Feasibility and a pathway to develop technology

Abstract: Small-scale photovoltaic-powered reverse osmosis (PVRO) desalination plants can provide fresh water to remote communities that do not have sufficient natural sources. For these systems to be practical, they must be both technically and economically feasible. This paper presents a research program that is focused on improving the feasibility of PVRO systems. As the first step in this pro gram, a methodology to evaluate the economic feasibility was developed. The results, reviewed here, show that the economic feasibility is a strong function of location. The results also show that increasing the efficiency of PVRO systems can extend their feasibility to currently marginal or un feasible locations. A focus of this research program is the development of smart control algorithms to increase system efficiency and improve feasibility. This paper presents PVRO system models which have been developed to evaluate the smart control algorithms. These models are verified using an experimental system also described here. Early experimental results are presented that show good agreement with the analytical models.

Nanofiltration vs. reverse osmosis for the removal of emerging organic contaminants in water reuse

Abstract: Reverse osmosis (RO) in existing water reuse facilities is a water industry standard. However, that approach may be questioned taking into consideration that “tight” NF can be equal or “better” than RO. NF can achieve the same removals of RO membranes when dealing with emerging organic contaminants (pharmaceuticals, pesticides, endocrine disruptors and others). Experiments using 18 emerging contaminants were performed using membranes NF200 and NF90 at bench-scale units, and for a more complete study, results of NF and RO pilot and full-scale experiments where compared to our experimental results. The removal results showed that NF can remove many emerging contaminants. The average removal by tight NF was 82% for neutral contaminants and 97% for ionic contaminants. The average removal by RO was 85% for neutral contaminants and 99% for ionic contaminants. Aquifer recharge and recovery (ARR) followed by NF can effectively remove emerging contaminants with removals over 90% when loose NF membranes are used.

Preparation and characterization of surface-modified zeolite-polyamide thin film nanocomposite membranes for desalination

Abstract: NaA type zeolites were surface modified with octadecyltrichlorosilane (OTS) and then added in polyamide layer of thin film composite (TFC) membranes to prepare surface-modified zeolite-polyamide thin film nanocomposite (TFN) membranes for desalination. The zeolites were characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The properties of membranes were characterized by scanning electron microscopy (SEM), contact angle measurement, and the permeation experiment, respectively. The results showed that zeolites were successfully surface-modified with OTS without changing of its structure. The SEM images depicted that the membrane morphology was more homogeneous and the zeolites aggregation in membranes was ameliorated after the zeolites were surface modified. The results of contact angle measurement indicated that the hydrophilic property of membranes was not changed after the zeolites were modified with the long alkyl chain organosilane. The RO performance results v...

Electrochemical degradation of some organic dyes by electrochemical oxidation on a Pb/PbO2 electrode

Abstract: This work investigated the electrocatalytic degradation of three types of textile dyes by electrochemical oxidation on lead dioxide anode. The influence of pH, current density, time of electrolysis, temperature, the conductive salt concentration and the initial dye concentrations were critically examined. The results of these influences are expressed in terms of the remaining organic compounds concentrations (color removal) and Chemical Oxygen Demand (COD removal). Also, both of the current efficiency and power consumption values are calculated. In this manuscript we report that, the highest electrocatalytic activity was achieved in the presence of NaCl (3 g/l), 30 mA/cm2, pH of 3 and temperature of 30 °C. The highest electroactivity could be attributed to indirect oxidation of the investigated dyes by the electrogenerated hypochlorite ions formed from the chloride oxidation. In addition, contribution from direct oxidation could also be possible via reaction of these dyes with the electrogenerated hydroxy...

Global trends and performances of desalination research

Abstract: This study was designed to evaluate the global scientific output of desalination research to assess the characteristics of the research tendencies and the research performances. Data were based on the online version of Science Citation Index, Web of Science from 1991 to 2008. Two main respects of the paper characteristics, performance of publication and research tendency, were analyzed. Performances of publications were assessed including document type, language, subject categories, journals, institutes, and countries. Research tendency was investigated by statistically analyzing the distribution of word in article title, author keyword, and keyword plus in different periods. Results show the desalination research mainly performed on subject category of chemical engineering. More specific, research might focus on membranes related research.

Nanofiltration as pretreatment for scale prevention in seawater reverse osmosis desalination

Abstract: Seawater contains high concentrations of sparingly soluble salts which can cause scaling of the membrane surface, which in turn can limit the productivity and water recovery potential of seawater reverse osmosis (SWRO). Nanofiltration (NF) pre-treatment of seawater can prevent scaling via preferential removal of scale-forming ions. Several studies have shown that the rejection of scale-forming ions can vary considerably depending on the membrane. The main objective of this study was to test a number of commercially available NF membranes with synthetic seawater in order to compare their performance and identify optimum membranes and operational conditions for the removal of compounds that are known to cause scaling (CaSO4 (s), Mg(OH)2, CaCO3 (s), etc.) in SWRO. Six membranes, supplied by several manufacturers, were tested in a laboratory-scale plant at various trans-membrane pressure differences. For the majority of membranes, the sulphate rejection was superior at 90%, which is very important for the pre...

Absorption of coal combustion flue gases in ionic liquids using different membrane contactors

Abstract: Carbon dioxide (CO2) and sulfur dioxide (SO2) are typical gases produced during coal combustion and their emissions have to be controlled and minimized in order to reduce environmental risks. Organic solvents are commonly used as absorption liquids for the chemical absorption of CO2 and SO2, and their use in combination with a membrane device is being studied recently. The volatile character of common solvents produces solvent losses due to their evaporation into the gas stream. Thus, the use of solvents with lower vapor pressure such as ionic liquids as absorption liquids may contribute to the performance of a zero solvent emission process. In the present study, mass transfer of CO2 is studied in a polypropylene hollow fiber membrane contactor when the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate is used as the absorption liquid. Mass transfer coefficients are compared with those obtained with a ceramic hollow fiber contactor for SO2 absorption. The overall mass transfer coefficient takes a valu...

On the controversial effect of sodium sulphate as supporting electrolyte on electrocoagulation process: A review

Abstract: One of the important factors for electrocoagulation (EC) process is the conductivity of the solution to be treated. Essential mechanisms in EC are charge neutralisation by metal (Fe/Al) hydroxocations and aggregation by van der Waals forces since fl occulation of pollutants with metal is caused by their adsorption on metal hydroxide aggregates. In order to enhance the EC process efficiency in organic wastewater effluents, sodium sulphate (Na2 SO4) has been used as a supporting electrolyte (SE) to increase the electric current diffusion in the EC cell. However, literature has reported controversial effect of sodium sulphate on EC process. This review tries to understand the sulphate effect on the EC reactions. Na2SO4 has been found less efficient than NaCl as SE in EC process for the removal of humic substances, oil-in-water emulsions, and fluoride. However, for unskimmed milk sample and cutting oil emulsion sulphate anions were found to be quite harmful both for electrical consumption and EC efficiency. T...

Treatment of saline aqueous solutions using direct contact membrane distillation

Abstract: The treatment of highly saline aqueous solutions using direct contact membrane distillation (DCMD) was evaluated in this study. Experiments were conducted using a flat sheet polytetrafluoroethylene membrane with nominal pore size of 0.22 µm. Seawater, reverse osmosis (RO) concentrate collected from a wastewater reclamation plant, and a synthetic solution containing 2,000 mg/L of CaSO4 were selected as the representative saline solutions. A gradual decline in permeate flux was observed at the beginning of the experiments when the seawater and RO concentrate solutions were treated using the DCMD process, most likely due to initial organic fouling and scaling. In contrast, when the saturated CaSO4 solution was used as the feed, the permeate flux was stable for approximately 300 min of operation. However, when these solutions were concentrated beyond their solubility limit, crystallization of the sparingly soluble salts occurred on the membrane surface, leading to a complete loss of permeate flux at the end o...

RO brine treatment and disposal methods

Abstract: More than 50 percent of countries in the world will likely face water stress or water shortages by 2025, and by 2050, as much as 75 percent of the world’s population could face water scarcity. Desalination technologies, particularly the reverse osmosis (RO) process, have increasingly been adopted to produce freshwater from alternative sources such as seawater and brackish water due to water scarcity. However, desalination applications have always been limited by the disposal costs of RO brine and the adverse impact of brine on the receiving environment. The scope of this paper is to identify technically and commercially RO brine disposal and treatment methods such as deep well injection, discharge into the sea, sanitary sewers, evaporation ponds, forward osmosis (FO), vacuum membrane distillation (VMD), vacuum-enhanced direct contact membrane distillation (VEDCMD), RO–NF Integrated system, bipolar membrane electrodialysis (BMED), electrodialysis (ED), Electrodialysis reversal (EDR), vibratory shear enhanc...

Adsorption characteristic studies of phosphorus onto laterite

Abstract: Soil has been widely used in many wastewater treatment systems, and proved to be an effective substrate for phosphorus removal and retention. It is significant to study its adsorption character istics by using appropriate theoretical models. In this study, laterite (or red soil) was selected as an example to investigate the adsorption characteristic of phosphorus onto soil with the Langmuir, Freundlich, and Redlich–Peterson isotherms by both the linear and non-linear regression methods. The adsorption experiment was conducted at the temperatures of 283, 288, 298, and 308 K, respectively, to choose the appropriate method and obtain the credible adsorption parameters for soil adsorption equilibrium studies. The results showed that the non-linear regression method would be a better way to compare the better fit of isotherms for the adsorption of phosphorus onto laterite. Both the two-parameter Freundlich and the three-parameter Redlich–Peterson isotherms had higher coefficients of determination for the adsorption of phosphorus onto laterite at various temperatures. In addition, a relationship between Freundlich isotherm parameters and Redlich– Peterson isotherm parameters was presented.

Development of an empirical model for fluoride removal from photovoltaic wastewater by electrocoagulation process

Abstract: Electrocoagulation experiments were conducted with bipolar aluminium electrodes to determine the optimum conditions for the fluoride removal from synthetic photovoltaic wastewater. A high fluoride concentration in community water supplies can cause fluorosis which has a detrimental effect on human health in particular on teeth and bones. A full 23 factorial design of experiments was used to obtain the best conditions of fluoride removal from water solutions. The three factors considered were initial fluoride concentration, applied potential, and supporting electrolyte dosage. Two levels for each factor were used; supporting electrolyte (0 and 100), applied potential (10 and 30 V), and initial fluoride concentration (20 and 25 mg/L). Results showed that the optimum conditions for fluoride removal from photovoltaic wastewater containing an initial fluoride concentration of 20 mg/L were a supporting electrolyte dose of 100 mg/L and an applied potential of 30 V. These gave a residual fluoride concentration of...

Adsorption of boron from aqueous solutions using activated carbon prepared from olive bagasse

Abstract: In this study, activated carbon was prepared from olive bagasse by physical activation. The pore properties including the BET surface area, pore volume, pore size distribution and average pore diameter were characterized. BET surface area of the activated carbon was determined as 803 m2g–1. In this study, boron removal from aqueous solutions by adsorption was investigated. In the batch mode adsorption studies, the effects of initial pH of solution, contact time, temperature and initial boron concentration of solution were examined. A comparison of kinetic models applied to the adsorption of boron onto activated carbon was evaluated for the pseudo-first order, pseudo-second order, intraparticle diffusion, Elovich and Bangham’s kinetic models. The experimental data fitted the pseudo-first order and intraparticle diffusion kinetic model. The thermodynamic parameters were also calculated. In the isotherm studies, the Langmuir, Freundlich and Dubinin –Radushkevich (DR) isotherm models were applied. The results...

Removal of nitrate and fluoride by nanofiltration – a comparative study

Abstract: High levels of nitrate and fluoride are causing a major threat to drinking water production in many countries worldwide. Besides reverse osmosis, recent publications indicate that nanofiltration (NF) is a promising technology to remove nitrate and fluoride from surface and groundwater. However, the tightness of the NF membranes plays a major role in the removal efficiency. Within this work, therefore, two commercial NF membranes supplied by Dow Water Solutions were selected for testing nitrate and fluoride rejection within a laboratory study. The NF 90 can be regarded as a “dense” membrane and the NF 270 as a “loose” NF membrane. Both membranes are negatively charged (MWCO of NF 90: 200 Da, NF 270: 300 Da). The experiments were conducted with nitrate-spiked and fluoride-spiked model and tap water. With regard to nitrate removal, only the NF 90 has the ability to comply with the recommended Maximum Contaminant Level (MCL) of 50 mg/L in the studied range of feed concentration (100–400 mg/L). For fluoride, t...

Removal of nitrate from groundwater using the technology of electrodialysis and electrodeionization

Abstract: In this paper, the technical capabilities of a lab-scale electrodeionization (EDI) process and its basic technology electrodialysis (ED) process that used for removing NO3 – from nitrate-contaminated groundwater were investigated. The EDI unit with three chambers (anode, diluted and cathode) was used; it utilized electricity to regenerate ion-exchange resins instead of chemicals. At first, the voltage-current (V-I) characteristic curves about the ED and EDI processes were studied, and then chose the optimum operating voltage which based on the curves. The effects of operational parameters (voltage, water flow rate and initial NO3 –-N concentration) on nitrate removal rate and concentration effect of ED and different ion-exchange resins, the proportion of anion and cation resins and the voltage used for regeneration of EDI were investigated. The results of ED showed that NO3 –-N concentration could be reduced from initial 50–300 mg/l to 1–6 mg/l, with the removal rate 99% and the conductivity could be redu...

Entrapment of Mg-Al layered double hydroxide in calcium alginate beads for phosphate removal from aqueous solution

Abstract: Mg-Al layered double hydroxide was entrapped in calcium alginate beads (LDH-alginate beads) for phosphate removal. A field emission scanning electron microscope (FESEM), combined with an energy dispersive X-ray spectrometer and an X-ray diffractometer, were used to analyze the properties of LDH-alginate beads. Batch and flow-through column experiments were performed to examine phosphate removal in LDH-alginate beads. FESEM images show that the cross-sectional surface of LDH-alginate beads was heterogeneous in surface topography, and LDH powders were intermingled with alginate polymers. Experimental results indicate that Mg-Al LDH-alginate beads are effective in the removal of phosphate. Batch experiments indicate that phosphate removal in 8% LDH-alginate beads was not sensitive to initial solution pHs between 4.9 and 8.9. Kinetic experiments demonstrate that phosphate removal reached equilibrium around 12 h of reaction time. Column experiments show that the removal capacity of 8% LDH-alginate beads was tw...

Application of advanced oxidation processes to remove refractory compounds from dye wastewater

Abstract: The purpose of this study was to investigate the efficacy of ozonation and three AOPs (O3/H2O2, O3/UV, and O3/H2O2/UV) on synthetic dye-containing wastewater with regard to the removal of chemical oxygen demand (COD) and color and biodegradability (BOD5/COD). At hydrogen peroxide levels above the optimal value, H2O2 tended to accumulate in the reactor, leading to a decrease in COD removal efficiency, because it acted as a radical scavenger. Higher recirculation flow rates increased COD and color removal in the combined UV process. Compared with the O3/H2O2 process, the O3/UV process enhanced COD removal mildly. Biodegradability increased approximately 12-fold after 150 min of retention time. Although all processes removed color within a short operational time, the O3/H2O2/UV process had the highest removal efficiency of COD and enhancement of biodegradability of the processes that we tested.

Adsorption of congo red using ethylenediamine modified wheat straw

Abstract: The natural wheat straw (NWS) was modified by ethylenediamine and the modified wheat straw (MWS) was used as adsorbent for removal of congo red (CR) from aqueous solution. Analysis of FTIR and nitrogen element showed that amino group was introduced to NWS. A batch system was applied to study the behavior of CR adsorption on MWS. Experiments were carried out as function of pH, adsorbent dosage, contact time and dye concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Redlich–Peterson models and Koble-Corrigan. Redlich–Peterson and Koble-Corrigan models provided the best correlation. The adsorption capacities from Langmuir model were 68.6 mg g–1 at 293 K. Adsorption kinetic data were fitted using the pseudo-first-order kinetic model, pseudo-second-order kinetic model, Elovish model and intraparticle diffusion model. The results showed that the Elovish model was best to fit the kinetic process, which suggested that ion exchange was one of main mechanism. The effective diffusi...

Impact of organic fractions identified by SEC and fluorescence EEM on the hydraulic reversibility of ultrafiltration membrane fouling by secondary effluents

Abstract: Loss of membrane filtration performance due to organic fouling is still a significant drawback for the application of low-pressure membranes in tertiary wastewater treatment. The present study investigates the relevance of different organic fractions present in secondary effluents in terms of hydraulically reversible and irreversible fouling of hollow-fibre ultrafiltration membranes. A good correlation between the hydraulically reversible filtration resistance and the total organic biopolymer concentration according to size exclusion chromatography (SEC) was observed. Qualitatively biopolymers consist mainly of polysaccharides as well as proteins with high molecular weight. Polysaccharides are retained by the membrane pores, but can be removed by simple UF backwashing. On the other hand, fluorescence excitation–emission matrix (EEM) analysis indicates that the extent of the hydraulically irreversible fouling correlates with the presence of protein-like substances. Removal of protein-like substances by bio...

Mixed matrix membranes for gas separation with special nanoporous fillers

Abstract: Special nanoporous fi llers for enhancing the gas separation performance of mixed matrix membranes (MMMs) are addressed in this work. The incorporation of small amounts of ordered mesoporous silica spheres (MSS) or exfoliated layered microporous titanosilicate UZAR-S1 (obtained from layered material JDF-L1) into a commercial polysulfone (PSF) membrane matrix was successfully carried out. The obtained results in terms of the separation of H2/CH4 and CO2/N2 mixtures were compared to those achieved with special fillers in the literature, such as mesoporous molecular sieves, lamellar zeolites and metal-organic frameworks. 8 wt.% MSS–PSF MMMs gave rise to H2/CH4 and CO2/N2 selectivities of 79.2 and 36.0 with H2 and CO2 permeabilities of 26.5 and 12.6 Barrer, respectively. 4 wt.% UZAR-S1-PSF MMM gave rise to H2/CH4 selectivity of 69.2 with H2 permeability of 11.5 Barrer.

SWOT analysis to assist identification of the critical factors for the successful implementation of water reuse schemes

Abstract: The reuse of urban wastewater has been recognised as an important alternative source of water and is a key aspect of sustainable water policy. As it is a promising innovation, a number of direct and indirect water reuse projects have been instigated and proposed, both nationally and internationally. However there is some uncertainty regarding the effectiveness and impact of these water reuse schemes (WRS). This study investigates the applicability of Strengths, Weaknesses, Opportunities, and Threats (SWOT) as an analysis tool for formulating the critical factors in terms of the implementation of water reuse schemes. Basically, this work adopts an existing multiple case study design method and makes use of SWOT to analyse all critical factors for each selected water reuse scheme. The strengths and weaknesses of successful and unsuccessful WRS are analysed followed by an assessment of the corresponding external opportunities and threats. On this basis, the critical factors considered for the successful implementation of the WRS are identified. A qualitative investigation using SWOT analysis has therefore been successfully implemented.