Water Journal : Water Journal July 2011
regular features 46 JULY 2011 water -- Special Report His overall message was that developments in molecular microbiology and microbial genomics are casting doubt on the efficacy of monitoring E. coli as a proxy for drinking water safety. There are new methods emerging. A second theme was that harnessing microbes will lead to better methods of managing water and wastewater for sustainability. The first part of his address reviewed the workings of the US EPA. Until recently there were 16 rule-making sections, mostly with a silo mentality, and an R&D group to service them all. The recent appointment of a new head for R&D has seen that simplified into four sections: water, air, health and green chemistry, the whole housed in a new zero-energy building, covered by a screen of working green algae. His excellent paper discusses the complicated history since 1971 of the operation of the Safe Drinking Water Act, with its Enhanced Surface Water Treatment rules and Contaminant Candidate List. To some extent the Americans have drawn on Australia's lead in using HACCP. In March 2010 they released a new approach to protecting drinking water and public health. Quantitative Microbial Risk Assessment is being used to define research framing. The significant pathways for human exposure are being identified, covering not only drinking water, but recreational and reuse areas. The fact that pneumonia can be transmitted through water (Legionella) presented a challenge, he said. Genome sequencing is a tool that has rapidly developed from a cost of many thousands of dollars to the order of $1000 for a sequence. It has shown that Petri-dish culture techniques can be misleading because some pathogens can exist in a viable but non-culturable state. An example of the power of sequencing is that it demonstrated that the post-earthquake outbreak of cholera in Haiti was not native, but an import of an Asian variant brought in by aid workers. We have relied on E. coli cultures as a proxy for absence of V. cholera, but we have found that E. coli can be a harmless environmental organism that can happily live in water-pipe biofilms. So while a concept of no detectable E. coli in 100ml grab samples is desirable, false positives are inevitable. To track a source or presence of faecal contamination, various Bacteroidetes (or viruses) may be better since they occur at 100 times the density of E. coli, and modern molecular methods of detection could make them a more specific indicator. He discussed pipeline disinfection, noting that chlorine/ chloramine are sledge-hammers, but European systems (which are cooler and shorter) do not need residuals; they work as healthy probiotic systems. Finally he discussed how engineered microbiology may be better harnessed to capture the imbedded energy and nutrients in wastewater, particularly if blackwater can be isolated from greywater. The written paper is stimulating and cites a number of valuable references. A new concept for Ozwater was the inclusion of a keynote address at the Closing Session, and this was given by Graeme Hugo, Professor of Geography at the University of Adelaide, on the vital topic of the demography of the population and its implications for water demand. He was a member of the Minister's Advisory Panel and his remarks had much relevance when a report was released two days later. Graeme Hugo, Professor of Geography, University of Adelaide. Looking at the global situation he noted that in 1970 the increase was 2.3%, but stabilisation was projected to be 12 billion by 2100. In 2009, the rate was 1.2% and stabilisation of 9 billion; in 2010 this was revised to 10 billion, from the current 6.9 billion. Most of this increase will occur in the less developed countries, particularly Asia, since there has been a massive decline in fertility rates in the developed nations, whose population is expected to increase from 1.23 billion to only 1.28 billion by 2050. His written paper details fertility and life expectancy rates around the world. Concentrating on Australia, he said the current situation is that it is growing as fast as the low-income countries, at 1.7%. Natural increase (births over deaths) has remained fairly steady at between 100,000 and 150,000 per year, with a peak in the 1970s and a rise to 150,000 from 2009 onwards. However, migration has averaged another 50,000 a year, with a recent peak of 300,000 in 2008--2009 (this figure is affected by a change in ABS methodology, some of them being students). It is currently about 200,000. Currently about half of Australians are either migrants or children of migrants. The fertility rate fell from 4 to 3 (per thousand population) in the years 1900--1940, but the baby boom after the war saw it rise to 4 again, before declining rapidly in the 1960s to about 1.7, with a slight rise to 1.96 now being evident. Since the end of the war, life expectancy has risen by an extra 13 years, due to living conditions and health services. Even men over 50 can expect nine extra years, with the average age of death now about 82 for men and 85 for women. However, the problem is the bulge as the 42% of baby boomers reach retirement age, with lower numbers of working age below them. Projections of future growth are notoriously sensitive to assumptions, but what is clear is that the percentage of 70+ people will rise disproportionately. Thus Australia faces a dilemma. Although we should move towards zero growth, there is a need for an increase in the number of younger workers. Dr Nicholas Ashbolt, Senior Research Microbiologist at US EPA.
Water Journal May 2011
Water Journal August 2011