In response to Sydney drinking water crisis last year and in coordination with the recommendations of the Final Report of Sydney Water Inquiry, A. C. E. A. Australian Chinese Engineers Association proposes the following improvements for water treatment technology:

1. Technical improvements Ê

1. Installation of activated carbon filtration system into the existing Sydney water treatment plants at a cost of A$35 million.
2. Use of a combination of chlorine dioxide and ozone for water disinfection, at a cost of A$22.23 million, to replace chlorine – the current disinfectant in use.

Total cost of the above technical improvements is about A$57.23 million in comparison with the estimated cost of A$300 million as was reported in the Final Report of Sydney Water Inquiry.

2. Management improvements Ê

1. Sharing the points of view with the Final Report of Sydney Water Inquiry that a strict control of catchment is the key factor to the quality of Sydney drinking water.
2. Establishing legislation for drinking water quality to make it in line with world trend of controlling the microbiological contamination of drinking water.

From July to September 1998, Sydney’s water supply was affected by outbreaks of parasites. Many industries suffered losses of business, particularly amongst the food industry, restaurant and dental services. Many of them have now organized class actions against Sydney Water.

The outbreak was caused by two kinds of parasites: Cryptosporidium and Giardia, which commonly exist in the cattle industry and are capable of infecting human, producing diarrhea and other symptoms of cryptosporidiosis and giardiasis. More seriously, if an elderly person with compromised immune system or an AIDS patient was infected, it would lead to life threatening situations.

Unfortunately these two parasites are widespread in the environment, particularly in the effluent of sewage. It is certain that the water quality will be affected if the sewage is running into water catchment. Therefore the following two steps should be taken to maintain the water quality free of microbial contamination:

1. The first step is to strictly control water resource and its catchment, protecting them from being affected by various microorganisms and other toxic matters. It is imperative to ensure water flowing into water treatment plant is clean.
2. The second step is to ensure that the water treatment system must be reliable and effective. The system should be able to carry out an effective disinfection to eradicate microorganisms from water and should not harm human at the same time.

The Final Report of the Sydney Water Inquiry Ê  a mechanism set up by the NSW government after the Sydney water crisis Ê  has identified many factors that contributed to the failure of Sydney’s drinking water, and has made a range of recommendations for future improvements. The immediate action by the NSW government, as a response to the Final Report of Sydney Water Inquiry, was to establish an authority to oversee the catchment. This action transferred the responsibilities from Sydney Water to the authority, which could now solely focus on the possible contamination of our valuable water resources.

However, in its technical recommendations, the Final Report of Sydney Water Inquiry concentrated on the improvement of the current water treatment technology, such as the improvement of operational backwash, the use of Prospect reservoir, and more research and development works by the reinstallation of the pilot plant of water treatment, etc. There is a brief statement in the final report, rejecting additional water treatment process such as the use of ozone or micro-filtration system in water treatment. The major reason for the rejection is its huge cost. Nevertheless, the door is still open in the Final Report for further discussion and review of new technology.

A.C.E.A., a not-for-profit organization that comprises of many Chinese engineers in Australia, has organized a number of meetings to discuss the Sydney water crisis. A proposal for the improvement of Sydney water treatment technology is further discussed below. This proposal is based on the experience of the water treatment technology used in the Langenau water treatment plant in Germany and the Guanting reservoir in China. This proposal has also been reviewed and supported by Dr Deng-Zhong Wu of the USEPA, Prof Radscheit of Germany, Dr Peter Wolfel of Langenau, Germany, Dr Natare of Japan, and Prof Gui-Zhi Li of China.

2. PROPOSAL FOR THE IMPROVEMENT OF SYDNEY DRINKING WATER

Currently, the activated carbon filter is installed in one of eleven water treatment plants in Sydney area, namely the North Richmond water treatment. None of the other ten water treatment plants, including the Prospect plant which supply 80% of Sydney drinking water, has activated carbon filter. The particles in the source water are removed in all Sydney water treatment plants by the process of coagulation, flocculation and sedimentation followed by filtration and disinfection.

Two reasons for not using the activated carbon filter were given in the Final Report of Sydney Water Inquiry, as follows:

1. Sydney’s water source is in good quality and hence, by presumption, requires no filtration with activated carbon.
2. The installation cost for a new water treatment process using the combination of ozone and activated carbon filtration will be as high as A$300 million (see Table 1).

Overseas experience indicated the installation cost of an activated carbon filter was about 3 to 4% of the construction cost of a water treatment plant. Our estimation for the cost of building an activated carbon filter into the existing Sydney’s water treatment plants is around 35 million Australian dollars (see Table 2)

Normally, the surface water used for drinking must be filtered by activated carbon during water treatment to remove toxic matters, colour and smell from the water. In the past, Sydney’s water sources had relatively low particle numbers similar to that of high quality water. Sydney Water even advertised that the water was crystal clear that it can be bottled. However, when heavy rain fell on catchment the source water became heavily polluted with all kinds of particles washed down from the catchment to the reservoir. The removal of all particles, toxic matters and microorganisms relies upon one level of technique, i.e. the coagulation-flocculation-sedimentation-filtration process. Once the volume of contaminants in the water exceeds the capacity of the system, the water becomes contaminated. This fact has been identified as the cause of parasite outbreak in Sydney’s drinking water.

Technically, the activated carbon filter is able to absorb particles. Under this condition, many organic contaminants and toxic matters, as well as the colour and smell of dirty water, are all removed. The microorganisms, which is smaller than the organic contaminants, will be largely blocked in the layers of activated carbon, leading to a dramatic reduction in the numbers of microorganisms present in the water prior to disinfection. This will lead further more to a large reduction in the cost of disinfection of water and, therefore, improve the quality of drinking water.

The advantage with activated carbon filter is that the activated carbon can be regenerated after some time of use, to keep the operation cost low. The loss of activated carbon after regeneration is estimated as about 10%.

Currently, there are two types of activated carbon filtration systems available worldwide, i.e. the gravity system and the pressurization system. The pressurization system is the European favour at present.

The Guangting reservoir in Beijing China, the main water supply to the city of Beijing, was once contaminated with microorganisms in 1990. The problem was solved in 1992 by installation of the activated carbon filtration process in its water treatment plant. Since then, no microbiological contamination has been reported, and the water quality has been maintained at a satisfactory level.

We believe that installation of the activated carbon filter into Sydney’s existing water treatment system, not only can remove a large range of toxic matters from source water, but can also achieve a high efficiency in water treatment and provide high quality drinking water to Sydney residents.

The Final Report of Sydney Water Inquiry has ruled out the introduction of ozone for water treatment, indicating that it would cost A$300 million to install the ozone and activated carbon filtration system. The other reason is that the current ozone technology cannot handle the large volume of water that Sydney requires. There is no mention of using chlorine dioxide as disinfectant.

Overseas experience indicates that the combination of chlorine dioxide and ozone for water treatment provides the best results for the eradication of microorganisms including the chlorine resistant parasites and hepatitis virus.

The estimated cost for building a water treatment system based on the combination of chlorine dioxide and ozone is about A$22.23 million (see Table 2). This technology can be implemented into the existing water treatment plants without major alternation.

Chlorine dioxide is a green yellowish gas. It can be easily manufactured on site at the water treatment plant. Chlorine dioxide has the following advantages over the chlorine:

1. It contains 2.6 times of available chlorine and 2.5 times of the oxidative effect as compared to chloride gas.
2. It provides short contact time with microorganisms and maintains a longer bactericide effect. This bactericide effect will follow the water flowing through the distribution system to the end-user whereas, with the current disinfectant (the chlorine), the bactericide effect fades away very quickly.
3. The nature of chlorine dioxide makes it the best disinfectant against microbial contamination of drinking water, in particular against chlorine resistant parasites, bacterial and virus, e.g. Bacillus anthrax, hepatitis virus, etc.
4. Chlorine dioxide has no toxic effect and does not react with organic matters to form carcinogen substance. Chlorine, however, does react with organic matters in the water forming trichlormethane Ê  a carcinogenic substance, if it is used at higher dosage to clear the heavily polluted water resource.
5. Chlorine dioxide is a multi-functional substance, which can be used in sterilization, preventing algae-growth, maintaining water freshness, providing oxidation ability, bleaching, and removing iron and manganese from water.

Chlorine dioxide is currently used as water disinfectant to replace chlorine in most cities of Europe and the United States.

Chlorine dioxide is manufactured according to the following reaction:

Manufacturing one kilogram (1 kg) of chlorine dioxide requires 1.34 kg of sodium chlorite (NaClO₂), and 0.55 kg of chlorine. The manufacturing cost is about A$13/kg. The unit cost added to each cubic meter of water is about A¢2.055 (see Table 2) when a dosage of 1.5 g of chlorine dioxide per cubic meter of water is applied.

Ozone is another strong oxidative agent. It is effective against the various bacteria, virus, parasites and its oocysts and cysts. It also has the function to remove the colour and odour from water and will not form carcinogenic substance. However, the cost of producing ozone is high. It must be used together with chlorine or chlorine dioxide to achieve high quality of disinfection of drinking water at a low cost.

The cost of producing ozone is about A$6/kg. The unit cost added to each cubic meter of water is about A¢1.034 (see Table 2) when a dosage of 2.0 g of ozone per cubic meter of water is applied.

The total unit cost of combination of ozone and chlorine dioxide, added to each cubic meter of water, is about A¢3.09 (see Table 2).

The combination technology of chlorine dioxide and ozone for water treatment can be implemented into the existing water treatment plants without much alteration, and it does not require a large investment.

2. Management Improvement

We do share the view points in the conclusion of the Final Report of the Sydney Water Inquiry that the strict control of catchment is the key to the quality of Sydney water. The establishment of Water Catchment Authority is the right direction to control the sewage flowing into catchment and to restrict the raising cattle and other animal within a certain radius of catchment. The legislation to control the catchment has passed the Parliament at the time of preparation of this proposal.

Currently, there is no legislation in NSW to govern the quality of drinking water. The quality of Sydney drinking water is abiding by the contracts between government, Sydney Water, and the private-run operators of water treatment plants.

The idea to establish legislation for the drinking water quality, in particular to include the parasites, was thoroughly examined by the Sydney Water Inquiry. However, there is no conclusion about the legislation.

We believe that Sydney and NSW residents should be given the guarantee of the quality of drinking water, on a par with the residents of other countries, such as Canada, the United States and Europe.

The quality of drinking water is monitored by parameters such as the appearance, chemical and physical properties, toxic matters and microbiological indicators. The microbiological indicator is the indication for pollution of water, and is expressed in terms of the number of coliform bacterial and total viable counts. Some other non-pathogenic microorganisms may be used as indicator for forecasting. It is possible to measure the degree of water contamination by using microbiological indicator and to estimate the presence of pathogenic microorganisms. The water quality standard varies from nation to nation, according to individual requirement. However, once the standard has been passed by the Parliament, it becomes the law. All the relevant parties should follow this law for the guarantee of quality of drinking water. Being an advanced country, Australia should have a Standard for drinking water quality.

3. OTHER DEFENSIVE OPINIONS AND OUR ARGUMENTS

During Sydney’s water crisis, many different opinions were put forward in defense of the NSW government and Sydney Water for its lacking of legislation to safeguard the quality of drinking water. Some of these defensive opinions selected from the media are as follows:

1. It is not necessary to treat drinking water to its highest standard because the volume of water used directly for drinking or for food preparation is about 1% of the total volume of water supplied to Sydney residents.
2. It would need a large investment for the government to upgrade the distribution system to provide quality water to more than one million families in Sydney area alone. The government cannot afford this amount of investment at the current economic situation
3. It is useless to set the standard for drinking water while the cause of recent outbreak of parasites is still unknown.
4. The Final Report of Sydney Water Inquiry states: ‘It is obvious that to set an arbitrary standard may not ensure safe water. It may also lead to significant costs without identifiable health benefits’, etc.

We believe that a legislation to pave the standard of drinking water is the only way to guarantee the quality of water. This is the trend around the world as it is happening in United States, Canada, and European countries. Linking the cost of upgrading the distribution system and the cost of urban development to the water quality is illogical and, in particular, guarantee of drinking water quality should not be viewed as a waste as some public opinions have said. The water quality and the water quantity supplied are two irrelevant issues. Once the water is used for drinking or for food preparation, no matter what percentage it is, the water quality will have the direct influence on the public health. The government should conduct a review regarding the costs on environmental, economic, and social fronts if the water is contaminated. A long-term strategy to deal with the water quality problem should be prepared by the government.

4. CONCLUSION

We believe that the following are the two important improvements to guarantee the quality in Sydney’s drinking water:

1. Strict control of catchment and establishment of the legislation for drinking water quality.
2. Replace the existing single-level process with the multi-level of water treatment technology, i.e. installation of activated carbon filtration system and disinfection of drinking water by using the combination of chlorine dioxide and ozone.

These two improvements can be coordinated to complement and enhance each other for the best performance of water treatment. An example would be to increase the dosage of chlorine dioxide to combat the excessive microorganisms in the water if the catchment is heavily contaminated or the filtration system is malfunctioned. Increasing chlorine dioxide in the water does not affect the water quality because it does not react with organic substance in the water to form carcinogenic substances, and does not produce any strange smell in the water. However, when chlorine is used as disinfectant, in particular when superchlorination is introduced, these side effects will occur.

The estimated cost for installation of activated carbon filtration system and installation of the combination of chlorine dioxide and ozone as disinfectant is about A$57.3 million. We believe it is worthwhile to put this amount of investment in water treatment technology for the sake of public health concerns of Sydney residents, as well as for the reputation of the Year 2000 Olympic City. It will provide a better protection of the quality of Sydney drinking water and will largely reduce the chance for recurrence of microbial contamination of our drinking water.

To all of us, the recent outbreak of parasites in Sydney drinking water is a warning, which should lead us to a review of the problems concerned with the management of catchment, the water treatment process, and disinfection process. We hope that this review will result in an improvement of water quality, and ensure the outbreak will not recur.