Current CRCWQT research projects on NOM

CRCWQT

2.2.1.2 IMPACTS OF DESTRATIFICATION OF RESERVOIR WATERS ON NOM AND ITS REMOVAL BY WATER TREATMENT PROCESSES
Project Leader: John van Leeuwen (AWQC)
Background: Issues to be addressed in this project relate to the impacts of reservoirs as storage systems on the character and quantity of natural organic matter in their waters and on the capacities of conventional water treatment processes to remove these organics from drinking water. The differences in the characters of organics from source waters to that in a drinking water reservoir (Myponga Reservoir, South Australia) and within the reservoir will be investigated. The aim of this project will be to determine the benefits, if any, of water storage in reservoirs on the potential for removal of organics by conventional water treatment processes. 

2.3.0.2 THE STRUCTURE AND CHEMISTRY OF NATURAL ORGANIC MATTER IN GROUNDWATERS FROM THE GNANGARA MOUND
Project Leader: Prof Robert Kagi (Curtin University)
Background: Natural organic matter (NOM) can cause a number of significant problems including increasing treatment costs, generation of disinfection by-products and bacterial regrowth in distribution systems. NOM is very heterogenous making structural studies difficult. Of particular interest are the large hydrophilic macromolecules that can be highly refractory and difficult to treat. The aim of this study is to determine functional characteristics of the NOM as determined by Fourier Transform Infrared Spectroscopy and 13 C NMR. Groups such as ether, ester and sulphur linkages will then be targeted to provide a systematic attackon the NOM macromolecule. Recent novel synthetic methods for mild oxidation, reduction hydrolysis and enzymatic cleavage will be used with degradation product identification by GC-MS. Micro-scale sealed vessel Pyrolysis GC-MS will also be used.

2.3.0.3 THE MONITORING OF ORGANIC AND BIOLOGICAL CONTAMINANTS IN RETICULATED WATER BY DIRECT PHOTOCHEMICAL DEGRADATION
Project Leader: Prof Robert Kagi (Curtin University)
Background: There is increasing concern within the water industry regarding the use of chemicals in water treatment especially treatments such as chlorine that generates potentially harmful by-products. Photoelectrochemical degradation by TiO2 is attracting interest due to its potential to oxidise nearly any organic or biological material. TiO2 can be used as suspended particles or as an immobilised system. While the former provides high degradation rates there are practical difficulties in recovering and regenerating the TiO2. The immobilised systems have a lower capacity and rate of degradation but are more practical for water supplies. The aim of this study is investigate ways of improving the photocatalytic efficiency of the immobilised systems.

2.3.1.1 CHARACTERISING NOM: DEVELOPMENT OF A DISSOLVED ORGANIC CARBON DETECTION SYSTEM FOR SIZE-EXCLUSION CHROMATOGRAPHY
Project Leader: Chris Chow (AWQC)
Background: This initiative involves development of new DOC analyses suitable for use with size exclusion chromatatography for molecular size characterisation. The traditional analysis of DOC with SEC is by inference from UV character, which is really a measure of the aromatic moieties only. The proposed detector can detect organic compounds, which cannot be detected by the UV detector. This detector can potentially be developed into a commercial product.This is a collaborative project between Curtin and AWQC staff.

2.3.1.3 ADVANCED CHARACTERISATION OF NOM IN AUSTRALIAN WATER SUPPLIES
Project Leader: Paul Greenwood (Curtin University of Technology)
Background: Understanding the origins and nature of natural organic matter (NOM) and its potential behaviour in water systems continues to be a high priority for the CRC for Water Quality and Treatment. This project will develop a tool-kit of spectroscopic and other analytical techniques aiding the advanced characterisation of NOM that will be tested in several regional studies (Perth, Adelaide, Canberra and Brisbane).

2.3.1.6 CHARACTERISATION AND TREATABILITY OF NATURAL ORGANIC MATTER IN GROUNDWATERS USED FOR DRINKING WATER
Project Leader: Paul Greenwood (Curtin University of Technology)
Background: The NOM of source waters can affect various aspects of water treatment and water quality. For example, it has the ability to cause unpleasant taste and odours, impart a brown colour in water, or act as a substrate for microbial growth. If not effectively removed by treatment, it may provide precursors for disinfection by-products and can contribute to biofilm formation and biological growth in the distribution system.The aims of this project are to conduct a detailed study of the origins, structural features and reactivity of NOM in a selection of Perth groundwaters, and to help optimise treatment processes which will ultimately contribute to the improved quality of drinking water supplied to consumers.

2.4.0.3 DEVELOPMENT OF COMBINED TREATMENT PROCESSES FOR THE REMOVAL OF RECALCITRENT ORGANIC MATTER
Project Leader: Ms Mary Drikas (AWQC)
Background: This project focuses on the study of treatment options for the removal of recalcitrant natural organic matter and methods to limit its effect on microfiltration membranes. Treatment processes, including coagulation, adsorption and membrane filtration will be the main area of study. It is intended to develop simple characterisation techniques for NOM to allow operators a useful tool to characterise their waters and assist in selecting and optimising treatment processes. Treatment options that remove recalcitrant NOM will be identified to improve treated water quality. This will include a detailed evaluation of the impact of MIEX on NOM. Treatment options to understand and reduce the impact of organic fouling on micro-filtration membranes will be a key focus. 

2.4.0.7 TREATMENT TECHNOLOGIES TO REDUCE TASTE AND ODOUR PROBLEMS AND DBP
Project Leader: Bob Kagi (Curtin University of Technology)
Background: Natural organic matter (NOM) is the cause of numerous problems in drinking water treatment. To achieve increased removal of NOM and eliminate taste and odour incidents, the Water Corporation of Western Australia has introduced a magnetic ion exchange resin (MIEX) treatment plant into the conventional treatment scheme at the Wanneroo groundwater treatment plant (WGWTP). This research aims to characterise the fractions of NOM that are preferentially removed by MIEX and those that remain after MIEX. The nature of these fractions will be compared to those removed by and remaining after conventional treatment. Several techniques will be developed and used for characterisation and the results should provide useful information for optimisation of these water treatment processes and for removal of DBP precursors. 

2.4.1.1 BIOLOGICAL PROCESSES FOR DISSOLVED ORGANIC CARBON (DOC) REMOVAL
Project Leader: Jurg Keller (University of Queensland )
Background: This project aims to develop and demonstrate specific biological treatment processes for the removal of DOC to complement and improve existing physico-chemical water treatment processes. 

The amount and character of naturally occurring organic matter has significant impacts on the transport of pollutants through the catchments, water treatment costs and disinfection efficiency and by-product formation. Improved knowledge of the functionality and reactivity of NOM will provide a more precise assessment of which compounds are of most concern in water treatment and which processes in the catchments or source waters hold most promise for management. There is close collaboration with the NOM studies in Program 3 and with the CRC for Soil and Land Management studies on the movement of phosphorus through soils.

• Investigate methods which improve the characterisation of NOM.
• Determine how the nature and concentration of NOM transported in a catchment is affected by seasonal variations, storm events and transport pathways.
• Improve the understanding of the significance of the characteristics of the NOM on the coagulation process.
• Improve the understanding of the interactions between NOM and phosphorous, and liming, on the concentration of phosphorous in reservoir storages.

POLYELECTROLYTES IN WATER TREATMENT

Polyelectrolytes are used in water treatment in two distinct ways, as coagulant aids and as primary coagulants. In the latter role, polymers have a number of advantages over inorganic coagulants, notably the smaller volume of sludge produced resulting in longer filter runs and reduced sludge management costs. In both roles, most of the added polyelectrolyte will be removed along with the destabilized colloidal impurities, but some may remain in the treated water. If so, there may be health implications from the polymer itself, and any byproducts formed from its interaction with disinfectants. However, little reliable information on flocculant carryover is available and consequently present-day regulations governing polyelectrolyte use are quite arbitrary and vary widely from country to country.

• Develop a rapid and reliable method, based on fluorescent labelling, for determining residual polymer in water treated with polymeric flocculants or coagulant aids.
• Explore the range of raw water compositions for which polyelectrolytes can be used as primary coagulants.

Membranes are reliable, use low amounts of chemical and are low maintenance, potentially making than cost effective and ideally suited for small communities. Both microfiltration and ultrafiltration membrane processes have been found to be particularly suitable in potable water treatment for the removal of finely divided suspended solids, especially bacteria, algae and protozoa such as Giardia and Cryptosporidium. They have been less successful in cost terms for the removal of dissolved contaminants such as colour and chemical pollutants.

This project aims to focus on the role of coagulation and adsorption processes in combination with microfiltration membrane processes. It is hoped that by studying such process combinations, the removal of natural organic compounds on conventional microfiltration membranes can be achieved with minimal fouling of the membrane surface. The potential advantage of this combination of processes is the development of a low operating cost membrane system that is capable of removing both soluble and particulate pollutants from drinking water.

Natural organics are one of the key factors in water treatment processes; they determine both coagulant and disinfectant dose, react with disinfectants to produce by-products, are a food source for bacterial growth in distribution systems, foul membranes limiting their use and are adsorbed strongly by activated carbon reducing its lifetime and usefulness for removal of pollutants. There is a need to reduce the amount of DOC present in our waters if water authorities are to maximise the cost-effective use of a range of treatment processes and to meet future limits on both disinfectant dose and disinfection by-products.

This project will seek a better understanding of the removal of natural organics by a range of currently available treatment processes, focussing on coagulation, oxidation and ion exchange resins. Some assessment of metal oxides and clays will also be undertaken. This should lead to the identification of particular components of the natural organic matter (NOM) that contribute to assimilable organic carbon (AOC) or are reactive to disinfection, forming by-products. It should also identify particular processes or steps in these processes that are more suited for removal of the problematic components of NOM.

Powdered activated carbon is used extensively for the removal of tastes and odours from drinking water, however it does not always produce the desired water quality. Preliminary studies have shown that activated carbons produced from different raw materials display a range of capacities for taste and odour removal. If the necessary characteristics of activated carbon for a particular contaminant (or a mixture of contaminants) are known, the best carbon can then be chosen (or produced), ensuring the most cost-effective use of activated carbon.

This project combines the study of adsorption of compounds that are of particular interest to the water industry of Australia (namely algal toxins, taste and odour compounds and dissolved natural organic material) and the simultaneous detailed study of the surface properties of the adsorbents. This information will define the mechanisms responsible for adsorption behaviour on different adsorbents, as well as the effect of NOM on removal of problem compounds. The solids under investigation include a range of commercially available activated carbons and several alternative, low cost adsorbents.

ALTERNATIVE DISINFECTION REGIMES

With increasing regulation of water quality, in particular the disinfection by-products (DBPs) produced by chlorine, there has been a move to replace chlorine with ozone. Ozone has its own associated problems, namely the production of AOC leading to biological growth in the distribution system, and the formation of by-products with their own health problems, eg, bromate.

An understanding of the factors affecting the formation of, and the nature of the precursors which lead to AOC and DBPs in water treatment processes involving ozone or ozone/chlorine, and factors which affect the formation of brominated DBPs such as bromate in ozonated water. This understanding should lead to management strategies for the control of these problems.

Biofilms can degrade drinking water quality by supporting bacterial regrowth and accelerating disinfectant decay. Water flow and quality in real distribution systems fluctuate widely in a relatively uncontrolled fashion and are difficult to measure in situ. It is consequently difficult and expensive to determine relationships between key ‘environmental’ (in-pipe) variables and biofilm development in real systems. Instead, this project does so in simulated pipe flow, using annular biofilm reactors under controlled laboratory conditions.

• Compare and improve methods of measuring nutrients available to bacteria and biofilm formation
• Determine nutrient(s) limiting bacterial growth in various Australian drinking waters
• Determine influence of nutrient levels in bulk water on biofilm development
• Determine significance of spatial structure and diversity of microorganisms in biofilms

DEVELOPMENT OF BIOLOGICAL TREATMENT SYSTEM FOR CONCENTRATED NATURAL ORGANICS STREAMS

Background

The disposal of the liquid NOM water treatment wastes is an increasing problem, likely to impede the broader application of new treatment technologies including membrane filtration and new ion exchange processes. This CRC project will investigate biological treatment of the concentrated NOM waste streams by studying the biodegradability of NOM in a bioreactor pilot plant.

Principal Aims

• Characterise the biodegradability of NOM in a typical waste stream
• Collect samples of appropriate biological agents for inoculation into bioreactor pilot plants to determine if a suitable biomass can be established to decolour and/or mineralise the NOM with and without pre-treatment,
• Develop an economical biological treatment system for concentrated NOM waste streams, and
• Devise environmentally friendly ways to dispose of biomass and treated liquid waste from this process.