DWESD - Latest Articles

Status of organochlorine pesticides in Ganga river basin: anthropogenic or glacial?

2012-01-30T00:00:00+01:00

Status of organochlorine pesticides in Ganga river basin: anthropogenic or glacial?

Drinking Water Engineering and Science Discussions, 5, 1-30, 2012

Author(s): P. K. Mutiyar and A. K. Mittal

This study reports the occurrences of organochlorine pesticides (OCPs) in Ganga river basin covering 3 states, i.e. Uttarakhand, Uttar Pradesh and Bihar covering 72% of total river stretch consisting of 82 sampling points covered through 3 sampling campaigns. Samples were monitored for 16 major OCPs, including HCHs, Endosulfan group, Aldrin group, DDTs and Heptachlor group pesticides.

The results showed the ng l⁻¹ levels contamination of OCPs in all the stretches sampled during these campaigns. The results also revealed that different type of OCPs were dominating in different stretches in accordance to the land use practices and agricultural runoff generated from those stretches. HCHs were most frequently detected (detection rate = 75%) in mountainous stretch; Endosulfans were prominent in UP (detection rate = 75%) stretch while BR stretch Aldrin group pesticides were paramount (detection rate = 34%). Source apportionment of the OCP's revealed that in the upper reaches of the Ganges i.e. in the state of Uttarakhand, the glacial melt may be responsible for the presence of OCP's. In the lower reaches, intensive agriculture and industrial activities may be significantly contributing these pesticides. The sample from tributaries of Ganga river were found to contain higher number of pesticides as well as higher concentrations. The maximum total pesticide in an individual sample from these sampling campaigns was found in Son river sample (0.17 μg l⁻¹, Location: Koilwar, Bhojpur, Bihar).

A new model for the simplification of particle counting data

2011-12-07T00:00:00+01:00

A new model for the simplification of particle counting data

Drinking Water Engineering and Science Discussions, 4, 151-172, 2011

Author(s): M. F. Fadal, J. Haarhoff, and S. Marais

This paper proposes a three-parameter mathematical model to describe the particle size distribution in a water sample. The proposed model offers some conceptual advantages over two other models reported on previously, and also provides a better fit to the particle counting data obtained from 321 water samples taken over three years at a large South Africa water utility. By using the data from raw water samples taken from a moderately turbid, large surface impoundment, as well as samples from the same water after treatment, typical ranges of the model parameters are presented for both raw and treated water. Once calibrated, the model allows the calculation of total particle number and volumes over any randomly selected size interval of interest.

Effect of fouling on removal of trace organic compounds by nanofiltration

2011-09-09T00:00:00+02:00

Effect of fouling on removal of trace organic compounds by nanofiltration

Drinking Water Engineering and Science Discussions, 4, 117-149, 2011

Author(s): S. Hajibabania, A. Verliefde, J. E. Drewes, L. D. Nghiem, J. McDonald, S. Khan, and P. Le-Clech

The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l⁻¹) were used to simulate fouling in NF under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.

Status of organochlorine pesticides in the drinking water well-field located in the Delhi region of the flood plains of river Yamuna

2011-08-12T00:00:00+02:00

Status of organochlorine pesticides in the drinking water well-field located in the Delhi region of the flood plains of river Yamuna

Drinking Water Engineering and Science Discussions, 4, 85-115, 2011

Author(s): P. K. Mutiyar, A. K. Mittal, and A. Pekdeger

This study presents the occurrence of pesticides in a well-field located in Yamuna flood plain of Delhi region. Ground water sampling campaigns were carried out during pre-monsoon and post-monsoon periods covering 21 bore-wells and 5 Ranney wells. Major 17 organochlorine pesticides (OCP's) along with other water quality parameters were monitored during this period. Pesticide concentrations were determined using GC- ECD, while GC-MS was used for confirmatory purposes. OCP's groups like ∑HCH, ∑DDT, endosulfan and aldrin were observed in this well-field. Concentration of OCPs from Ranney wells exceeded the limit (1 μg l⁻¹) prescribed by the Bureau of Indian Standards (BIS) in pre-monsoon season, though OCP levels in bore wells were within BIS limits. However, these levels were very close to the World Health Organisation (WHO) and European Union (EU) limit of for pesticides (0.5 μg l⁻¹) in many samples. Bore well produced better quality water compared to the water from Ranney wells. Although, the level of OCP's was slightly lower than prescribed limit of national regulatory agency but such low doses may cause long-term damage to human populations if such water is consumed for longer durations. At low doses OCP's acts as endocrine disrupting agent and cause metabolic disorders in local population.

Experimental investigation of turbulent particle radial transport processes in DWDS using optical tomography

2011-07-06T00:00:00+02:00

Experimental investigation of turbulent particle radial transport processes in DWDS using optical tomography

Drinking Water Engineering and Science Discussions, 4, 61-83, 2011

Author(s): R. Floris and P. van Thienen

Several transport mechanisms govern the cross-sectional particle distribution in fully developed turbulent flow in a pipe. These transport mechanisms affect particle load deposition as well as particle resuspension, which are identified as principal protagonists in the build-up of potential discolouration risk in drinking water distribution systems (DWDS). Both are to a large degree controlled by particle size and flow conditions. However, so far, these relationships are not completely understood in the context of DWDS.

In this research we have attempted to identify under which conditions particles suspended in water are transported towards the pipe wall, which generate favourable conditions for deposition. Experimental results are reported and then compared, qualitatively and quantitatively, to the theoretical predictions in the regime transport map for turbulent flow proposed by van Thienen et al. (2011a). The research was conducted by completing a series of experiments in a laboratory test facility with different hydraulic regimes and different particle size ranges. A newly developed optical tomography measurement system was used in order to produce cross-sectional images of particle concentration in water flowing inside a pipe. The experimental results allowed us to identify flow conditions and particles sizes under which gravitational settling and turbophoresis dominated the radial particle transport. These findings show a good correspondence between experimental data and theoretical predictions on the occurrence of turbophoresis and lead to a better understanding of the processes that increase the potential discolouration risk in DWDS.

Application of optical tomography in the study of discolouration in drinking water distribution systems

2011-06-27T00:00:00+02:00

Application of optical tomography in the study of discolouration in drinking water distribution systems

Drinking Water Engineering and Science Discussions, 4, 39-59, 2011

Author(s): P. van Thienen, R. Floris, and S. Meijering

Theories describing the turbulent deposition of particles from aerosols have recently been applied to drinking water distribution. In order to allow the study of these processes in a quantitative way and internally observe a cloud of suspended particles in a pipe, we have developed an optical tomography technique and measuring device using low cost electronic components specifically for this application. The mathematical methodology and the electronic device are described in this paper, and tests of both the mathematical approach and the actual device are presented. We conclude that the described methodology may provide a valuable tool for the study of processes related to drinking water discolouration in the lab.

CLIPS based decision support system for Water Distribution Networks

2011-03-07T00:00:00+01:00

CLIPS based decision support system for Water Distribution Networks

Drinking Water Engineering and Science Discussions, 4, 1-38, 2011

Author(s): S. Kulshrestha and R. Khosa

The Water Distribution Networks (WDN) are managed by experts, who, over the years of their association and responsibility, acquire an empirical knowledge of the system and, characteristically, this knowledge remains largely confined to their respective personal domains. In the event of any new information and/or emergence of a new problem, these experts apply simple heuristics to design corrective measures and cognitively seek to predict network performance. The human interference leads to inefficient utilization of resources and unfair distribution. Researchers over the past, have tried to address to the problem and they have applied Artificial Intelligence (AI) tool to automate the decision process and encode the heuristic rules. The application of AI tool in the field of WDN management is meager. This paper describes a component of an ongoing research initiative to investigate the potential application of artificial intelligence package CLIPS (short for C Language Integrated Production System, developed at NASA/Johnson Space Center) in the development of an expert decision support system for management of a water distribution network. The system aims to meet several concerns of modern water utility managers as it attempts to formalize operational and management experiences, and provides a frame work for assisting water utility managers even in the absence of expert personnel.

Groundwater contamination due to lead (Pb) migrating from Richmond municipal landfill into Matsheumhlope aquifer: evaluation of a model using field observations

2010-10-18T00:00:00+02:00

Groundwater contamination due to lead (Pb) migrating from Richmond municipal landfill into Matsheumhlope aquifer: evaluation of a model using field observations

Drinking Water Engineering and Science Discussions, 3, 251-269, 2010

Author(s): M. Kubare, C. Mutsvangwa, and C. Masuku

Disposal of solid waste in landfills is an economic option for many municipalities in developing countries where alternatives like incineration and composting are costly. However, groundwater pollution from the leachate generated within the landfill and migrating through the bottom liner material into the underlying groundwater aquifers remains a major public health concern. In our study, we evaluated the application of a mathematical model to determine the aerial extent of unacceptable groundwater contamination due to lead migrating from the Richmond landfill leachate into the underlying Matsheumhlope unconfined aquifer. A one-dimensional advection-dispersion model was applied to predict the down-gradient migration of lead into the aquifer. Linear sorption and first-order decay were considered as the dominant contaminant sink mechanisms for lead. Lead concentrations in the monitoring wells at the landfill site were used as the source term. The lead migration from the landfill was determined by water quality sampling from boreholes situated down-gradient of the landfill. The model simulations gave a good fit of the field results. The safe distance for potable water abstraction was determined to be 400 m, and the model simulations showed that the aerial extent of the pollution will increase with time. The model is most sensitive to the partition coefficient, hydraulic conductivity and longitudinal dispersivity, whilst it exhibits no sensitivity to the lead decay coefficient.

Water supply project feasibilities in fringe areas of Kolkata, India

2010-09-22T00:00:00+02:00

Water supply project feasibilities in fringe areas of Kolkata, India

Drinking Water Engineering and Science Discussions, 3, 199-249, 2010

Author(s): K. Dutta Roy, B. Thakur, T. S. Konar, and S. N. Chakrabarty

Water supply management to the peri-urban areas of the developing world is a complex task due to migration, infrastructure, paucity of fund etc. A cost-benefit methodology particularly suitable for the peri-urban areas has been developed for the city of Kolkata, India. The costs are estimated based on a neural network estimate. The water quality of the area is estimated from samples and a water quality index has been prepared. A questionnaire survey in the area has been conducted for relevant information like income, awareness and willingness to pay for safe drinking water. A factor analysis has been conducted for distinguishing the important factors of the survey and subsequent multiple regressions have been conducted for finding the relationships for the willingness to pay. A system dynamics model has been conducted to estimate the trend of increase of willingness to pay with the urbanizations in the peri-urban areas. A cost benefit analysis with the impact of time value of money has been executed. The risk and uncertainty of the project is investigated by Monte Carlos simulation and tornado diagrams. It has been found that the projects that are normally rejected in standard cost benefit analysis would be accepted if the impacts of urbanizations in the peri-urban areas are considered.

Metals releases and disinfection byproduct formation in domestic wells following shock chlorination

2010-06-04T00:00:00+02:00

Metals releases and disinfection byproduct formation in domestic wells following shock chlorination

Drinking Water Engineering and Science Discussions, 3, 177-198, 2010

Author(s): M. Walker and J. Newman

Shock chlorination is used for rapid disinfection to control pathogens and nuisance bacteria in domestic wells. A typical shock chlorination procedure involves adding sodium hypochlorite in liquid bleach solutions to achieve concentrations of free chlorine of up to 200 ppm in the standing water of a well. The change in pH and oxidation potential may bring trace metals from aquifer materials into solution and chlorine may react with dissolved organic carbon to form disinfection byproducts. We carried out experiments with four wells to observe and determine the persistence of increased concentrations of metals and disinfection byproducts. Water samples from shock chlorinated wells were analyzed for Pb, Cu, As, radionuclides and disinfection byproducts (haloacetic acids and trihalomethanes), immediately prior to treatment, after sufficient contact time with chlorine had elapsed, and at intervals determined by the number of casing volumes purged, for up to four times the well casing volume.

Elevated concentrations of lead and copper dissipated in proportion to free chlorine (measured semi-quantitatively) during the purging process. Trihalomethanes and haloacetic acids were formed in wells during disinfection. In one of two wells tested, disinfection byproducts dissipated in proportion to free chlorine during purging. However, one well retained disinfection byproducts and free chlorine after four well volumes had been purged. Although metals returned to background concentrations in this well, disinfection byproducts remained elevated, though below the MCL, likely because purging volume was insufficient. Simple chlorine test strips may be a useful method for indicating when purging is adequate to remove metals and disinfection by-products mobilized and formed by shock chlorination.

Understanding and managing large sensor networks

2010-04-12T00:00:00+02:00

Understanding and managing large sensor networks

Drinking Water Engineering and Science Discussions, 3, 149-175, 2010

Author(s): D. D. Ediriweera and I. W. Marshall

The water supply industry is trialing a range of sensor network designs for monitoring distributed infrastructure. The paper investigates the performance of such a sensor system deployed to monitor a water distribution network. The study reveals up to one fifth of the data intended to be collected either to be missing or erroneous. Findings reinforce the importance of in-depth design consideration of all aspects of large scale sensor systems, and the necessity for expertise on every detail of the system, or access to a rule set which embeds this knowledge allowing non-specialists to make near optimal choices. First steps towards defining such a rule set is presented here with supporting evidence.

Negative pressures in full-scale distribution system: field investigation, modelling, estimation of intrusion volumes and risk for public health

2010-03-12T00:00:00+01:00

Negative pressures in full-scale distribution system: field investigation, modelling, estimation of intrusion volumes and risk for public health

Drinking Water Engineering and Science Discussions, 3, 133-148, 2010

Author(s): M. C. Besner, G. Ebacher, B. S. Jung, B. Karney, J. Lavoie, P. Payment, and M. Prévost

Various investigations encompassing microbial characterization of external sources of contamination (soil and trenchwater surrounding water mains, flooded air-valve vaults), field pressure monitoring, and hydraulic and transient analyses were conducted in the same distribution system where two epidemiological studies showing an increase in gastrointestinal illness for people drinking tap water were conducted in the 1990's. Interesting results include the detection of microorganisms indicators of fecal contamination in all external sources investigated but at a higher frequency in the water from flooded air-valve vaults, and the recording of 18 negative pressure events in the distribution system during a 17-month monitoring period. Transient analysis of this large and complex distribution system was challenging and highlighted the need to consider field pressure data in the process.

Effects of ozonation and temperature on biodegradation of natural organic matter in biological granular activated carbon filters

2010-02-01T00:00:00+01:00

Effects of ozonation and temperature on biodegradation of natural organic matter in biological granular activated carbon filters

Drinking Water Engineering and Science Discussions, 3, 107-132, 2010

Author(s): L. T. J. van der Aa, L. C. Rietveld, and J. C. van Dijk

Four pilot (biological) granular activated carbon ((B)GAC) filters were operated to quantify the effects of ozonation and water temperature on the biodegradation of natural organic matter (NOM) in (B)GAC filters. Removal of dissolved organic carbon (DOC), assimilable organic carbon (AOC) and oxygen and the production of carbon dioxide were taken as indicators for NOM biodegradation. Ozonation stimulated DOC and AOC removal in the BGAC filters, but had no significant effect on oxygen removal and carbon dioxide production. The temperature had no significant effect on DOC and AOC removal, while oxygen removal and carbon dioxide production increased with increasing temperature. Multivariate linear regression was used to quantify these relations. In summer the ratio between oxygen consumption and DOC removal exceeded the theoretical maximum of 2.5 g O₂·g C⁻¹ and the ratio between carbon dioxide production and DOC removal exceeded the theoretical maximum of 3.7 g CO₂·g C⁻¹. Bioregeneration of large NOM molecules could explain this excesses and the non-correlation between DOC and AOC removal and oxygen removal and carbon dioxide production. However bioregeneration of large NOM molecules was considered not likely to happen, due to sequestration.

Rapid evaluation of water supply project feasibility in Kolkata, India

2010-01-22T00:00:00+01:00

Rapid evaluation of water supply project feasibility in Kolkata, India

Drinking Water Engineering and Science Discussions, 3, 65-105, 2010

Author(s): K. Dutta Roy, B. Thakur, T. S. Konar, and S. N. Chakrabarty

Mega cities in developing countries are mostly dependent on external funding for improving the civic infrastructures like water supply. International and sometimes national agencies stipulate financial justifications for infrastructure funding. Expansion of drinking water network with external funding therefore requires explicit economic estimates. A methodology suitable for local condition has been developed in this study. Relevant field data were collected for estimating the cost of supply. The artificial neural network technique has been used for cost estimate. The willingness to pay survey has been used for estimating the benefits. Cost and benefit have been compared with consideration of time value of money. The risk and uncertainty have been investigated by Monte Carlo's simulation and sensitivity analysis. The results in this case indicated that consumers were willing to pay for supply of drinking water. It has been also found that supply up to 20 km from the treatment plant is economical after which new plants should be considered. The study would help to plan for economically optimal improvement of water supply. It could be also used for estimating the water tariff structure for the city.

MUWS (Microbiology in Urban Water Systems) – an interdisciplinary approach to study microbial communities in urban water systems

2010-01-22T00:00:00+01:00

MUWS (Microbiology in Urban Water Systems) – an interdisciplinary approach to study microbial communities in urban water systems

Drinking Water Engineering and Science Discussions, 3, 43-64, 2010

Author(s): P. Deines, R. Sekar, H. S. Jensen, S. Tait, J. B. Boxall, A. M. Osborn, and C. A. Biggs

Microbiology in Urban Water Systems (MUWS) is an integrated project, which aims to characterize the microorganisms found in both potable water distribution systems and sewer networks. These large infrastructure systems have a major impact on our quality of life, and despite the importance of these systems as major components of the water cycle, little is known about their microbial ecology. Potable water distribution systems are large, highly interconnected and dynamic, and difficult to control. Sewer systems are also large and subject to time varying inputs and demands. Their performance also faces increasing loading due to increasing urbanization and longer-term environmental changes. Therefore, understanding the link between microbial ecology and any potential impacts on short or long-term engineering performance is important. By combining the strengths and research expertise of civil-, biochemical engineers and molecular microbial ecologists, we aim to link the abundance and diversity of microorganisms to physical and engineering variables so that novel insights into the ecology of microorganisms within both water distribution systems and sewer networks can be explored. By presenting the details of this multidisciplinary approach, and the principals behind the molecular microbiological methods and techniques that we use, this paper will demonstrate the potential of an integrated approach to better understand urban water system function and so meet future challenges.

I-WARP: individual water main renewal planner

2010-01-13T00:00:00+01:00

I-WARP: individual water main renewal planner

Drinking Water Engineering and Science Discussions, 3, 25-41, 2010

Author(s): Y. Kleiner and B. Rajani

I-WARP is based upon a nonhomogeneous Poisson approach to model breakage rates in individual water mains. The structural deterioration of water mains and their subsequent failure are affected by many factors, both static (e.g., pipe material, pipe size, age (vintage), soil type) and dynamic (e.g., climate, cathodic protection, pressure zone changes). I-WARP allows for the consideration of both static and dynamic factors in the statistical analysis of historical breakage patterns. This paper describes the mathematical approach and demonstrates its application with the help of a case study. The research project within which I-WARP was developed, was jointly funded by the National Research Council of Canada (NRC), and the Water Research foundation (formerly known as the American Water Works Association Research Foundation – AwwaRF) and supported by water utilities from USA and Canada.

A bottom-up approach of stochastic demand allocation in water quality modelling

2010-01-04T00:00:00+01:00

A bottom-up approach of stochastic demand allocation in water quality modelling

Drinking Water Engineering and Science Discussions, 3, 1-24, 2010

Author(s): E. J. M. Blokker, J. H. G. Vreeburg, H. Beverloo, M. Klein Arfman, and J. C. van Dijk

An "all pipes" hydraulic model of a DMA-sized drinking water distribution system was constructed with two types of demand allocations. One is constructed with the conventional top-down approach, i.e. a demand multiplier pattern from the booster station is allocated to all demand nodes with a correction factor to account for the average water demand on that node. The other is constructed with a bottom-up approach of demand allocation, i.e., each individual home is represented by one demand node with its own stochastic water demand pattern.

The stochastic water demand patterns are constructed with an end-use model on a per second basis and per individual home. The flow entering the test area was measured and a tracer test with sodium chloride was performed to measure travel times. The two models were evaluated on the predicted sum of demands and travel times, compared with what was measured in the test area.

The new bottom-up approach performs at least as well as the conventional top-down approach with respect to total demand and travel times, without the need for any flow measurements or calibration measurements. The bottom-up approach leads to a stochastic method of hydraulic modelling and gives insight into the variability of travel times as an added feature beyond the conventional way of modelling.

Online modelling of water distribution systems: a UK case study

2009-12-23T00:00:00+01:00

Online modelling of water distribution systems: a UK case study

Drinking Water Engineering and Science Discussions, 2, 279-294, 2009

Author(s): J. Machell, S. R. Mounce, and J. B. Boxall

Hydraulic simulation models of water distribution networks are routinely used for operational investigations and network design purposes. However, their full potential is often never realised because, in the majority of cases, they have been calibrated with data collected manually from the field during a single historic time period and, as such, reflect the network operational conditions that were prevalent at that time, and they are then applied as part of a reactive, desktop investigation. In order to use a hydraulic model to assist proactive distribution network management its element asset information must be up to date and it should be able to access current network information to drive simulations. Historically this advance has been restricted by the high cost of collecting and transferring the necessary field measurements. However, recent innovation and cost reductions associated with data transfer is resulting in collection of data from increasing numbers of sensors in water supply systems, and automatic transfer of the data to point of use. This means engineers potentially have access to a constant stream of current network data that enables a new era of "online" modelling that can be used to continually assess standards of service compliance for pressure and reduce the impact of network events, such as mains bursts, on customers. A case study is presented here that shows how an online modelling system can give timely warning of changes from normal network operation, providing capacity to minimise customer impact.

Fluorescence spectroscopy as a tool for determination of organic matter removal efficiency at water treatment works

2009-12-23T00:00:00+01:00

Fluorescence spectroscopy as a tool for determination of organic matter removal efficiency at water treatment works

Drinking Water Engineering and Science Discussions, 2, 259-278, 2009

Author(s): M. Z. Bieroza, J. Bridgeman, and A. Baker

Organic matter (OM) in drinking water treatment is a common impediment responsible for increased coagulant and disinfectant dosages, formation of carcinogenic disinfection-by products, and microbial re-growth in distribution system. The inherent heterogeneity of OM implies the utilization of advanced analytical techniques for its characterization and assessment of removal efficiency. Here, the application of simple fluorescence excitation-emission technique to OM characterization in drinking water treatment is presented. The fluorescence data of raw and clarified water was obtained from 16 drinking water treatment works. The reduction in fulvic-like fluorescence was found to significantly correlate with OM removal measured with total organic carbon (TOC). Fluorescence properties, fulvic- and tryptophan-like regions, were found to discriminate OM fractions of different removal efficiencies.

The results obtained in the study show that fluorescence spectroscopy provides a rapid and accurate characterization and quantification of OM fractions and indication of their treatability in conventional water treatment.

NOM characterization and removal at six Southern African water treatment plants

2009-11-10T00:00:00+01:00

NOM characterization and removal at six Southern African water treatment plants

Drinking Water Engineering and Science Discussions, 2, 231-257, 2009

Author(s): J. Haarhoff, M. Kubare, B. Mamba, R. Krause, T. Nkambule, B. Matsebula, and J. Menge

Organic pollution is a major concern during drinking water treatment. Major challenges attributed to organic pollution include the proliferation of pathogenic micro-organisms, prevalence of toxic and physiologically disruptive organic micropollutants, and quality deterioration in water distribution systems. A major component of organic pollution is natural organic matter (NOM). The operational mechanisms of most unit processes are well understood. However, their interaction with NOM is still the subject of scientific research. This paper takes the form of a metastudy to capture some of the experiences with NOM monitoring and analysis at a number of Southern African Water Treatment Plants. It is written from the perspective of practical process selection, to try and coax some pointers from the available data for the design of more detailed pilot work. NOM was tracked at six water treatment plants using dissolved organic carbon (DOC) measurements. Fractionation of the DOC based on biodegradability and molecular weight distribution was done at a water treatment plant in Namibia. A third fractionation technique using ion exchange resins was used to assess the impact of ozonation on DOC. DOC measurements alone did not give much insight into NOM evolution through the treatment train. The more detailed characterization techniques showed that different unit processes preferentially remove different NOM fractions. Therefore these techniques provide better information for process design and optimisation than the DOC measurement which is routinely done during full scale operation at these water treatment plants. Further work will focus on streamlining and improving the reproducibility of selected fractionation techniques, characterization of NOM from different water sources, and synthesis of the results into a systematic, practical guideline for process design and optimisation.