HKU Bulletin September 2007 (Vol. 9 No. 1)

14 COVER STORY 15 We Must Do Better, Says Sustainability Expert W e should stop considering waste water a nuisance and look at it as a valuable substance, according to a leading expert in sustainability. Time is running out, said Professor Peter Wilderer, Director of the Institute of Advanced Studies on Sustainability at the European Academy of Sciences and Arts, Munich, to change the way we utilize water. At the William Mong Distinguished Lecture in Engineering and Computer Science, he told a packed audience that we have ten to 15 years to make the necessary shift. We have plenty of motivation, he stressed, citing population growth, migration and urbanization, global warming and climate change and over-usage of natural resources. “At the moment we have 6.5 billion people. By 2035 the world population is expected to be beyond eight billion, with 65 per cent of them living in cities. “Growth of the urban population results in over-proportional increase in demand for water and food, and results in huge waste water generation. When people move to cities they demand a better lifestyle, this results in over-proportional use of water resources and land. Time is more than ripe to re-think what we are doing and shift the paradigm.” Wilderer explained: “The old paradigm is to deliver water with sufficient quantity and quality and to remove waste. But when you look at it in practice we procure waste water and we want to get rid of it as fast as possible. We get water from a reservoir, treat it if necessary, then send it to customers. We use it, waste water is produced which goes through a system of sewage pipes; it will get some treatment, then goes back to nature. We call this the once-through system. “The technology we use today dates back to ancient civilization, to the Romans. What we have is contemporary applications of ancient systems. The old paradigm for waste water is obsolete.” Wilderer’s new paradigm is based on the fact that we are living in a knowledge society. “Shouldn’t we be able to come up with a more intelligent solution? We should use our brains instead of sewers.” Instead of single discharge, he said, we should consider the re-use of water. We should see catchment, sanitation and water supply embedded in an enabling frame. “As engineers we have to solve problems as they appear. To do this we cannot work alone. We need investment, insurance and professors to teach a new generation. But we also need artists, philosophers, law makers, politicians to be involved as well. We need the media to report. We need architects, urban planners, and the input of land users. We need co-operation with industry, agriculture, enterprises. “Without the rest on board we can’t work. So we have to try to get the enabling environment right. We need a more intra-disciplinary approach, working with chemists, economists, social scientists, we should ask the customer what they want and respect the civil society so it becomes a trans-disciplinary approach.” “So far ours has been a response to disaster approach,” he said. “And the technology has been developed under wet, moderate, wealthy conditions. Are we sure this also fits in situations where people do not have money? Is the old technology the best solution to those situations? Is it reasonable to apply the old technology to Calcutta, or Africa or places where the planet is hot and dry?” Wilderer offered several options for moving forward. One is integrated water resources management (IWRM) - a philosophy of seeing the whole picture; a systems approach that sees the management of water in a holistic way. But success demands a change in the attitude by political decision makers. Another hypothesis is to relieve pressure on metropolitan areas by investing in job opportunities in the countryside. Source separation is also an option. “We could separate grey water from urine and faeces. It makes more sense to collect the grey, yellow and brown water separately. This would have to be done when the house is under construction so would need the architects on board. “Grey water can be easily treated and directly used for flushing, cleaning or irrigation. Faeces could be used for making energy. We could have a decentralized approach, treating the water of single houses like they do in Tokyo. Separate collection and treatment will save a lot of energy. “So the old assumption is that waste water is a nuisance, the new assumption is that waste water is a source. We have to develop this technology to bring it to the market quickly because this is a rapidly-changing world.” But, he stressed, technology alone cannot solve the problems. “We have to consult with all the stakeholders, participation is very important.”