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Sustainable and profitable environmental technology alternative to inefficient western sewage

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16.11.2006

The Western world purifies its wastewater in a costly and inefficient fashion, which also sets a poor example for developing countries. It is more sustainable – and even profitable – to reuse scarce and often costly resources such as water and fertilisers.

The environmental technology required to achieve this goal is still getting insufficient attention, said Jules van Lier in his inaugural address, professor in Anaerobic Wastewater Treatment for Reuse and Irrigation at Wageningen University.

Prof. Van Lier contends that the greatest concern for ourselves and our progeny is the exhaustion and unequal distribution of resources that are essential for maintaining our society. Greater pressure on these resources leads to even greater social inequality. And this in turn can lead to worldwide social unrest with a fundamental struggle for resources. In contrast, he believes that the concerns about the greenhouse effect and the attempts to limit climate change are futile because there is little that can be done about these problems and they draw attention away from the real issue: the exhaustion of the Earth's resources.

Dealing responsibly with the limited amount of water is one of the greatest challenges for the coming decades, states Van Lier. Only 0.01 - 0.02 percent of all the water on Earth is suitable for human consumption and use ("many times less than the standard measurement error"). Freshwater is a renewable resource; the water that is consumed by a resident of Amsterdam has already passed through a German's body. Van Lier believes it is worthwhile to include the reuse of water and the recovery of resources as part of the basic design of the water chain, where the final user of the water partly determines its quality, and therefore the cost of purification. Extensive purification of water at high cost is pointless if this is not strictly necessary. For example, using a great deal of energy to initially remove fertilisers from wastewater that will be used later in agricultural production cannot be justified. This is especially the case if the land has to be fertilised anyway. Van Lier advocates a much more realistic approach – which could be a breakthrough for developing countries – by implementing wastewater purification on a large scale. He believes this is essential because long periods of pollution are creating a time bomb underneath society. At this time, 1.8 million people die annually by drinking contaminated water, of which 90% are children younger than five, while 2.4 billion people do not even have access to adequate sanitary facilities.

Inefficient

The Western world processes its wastewater inefficiently. In our households, we dilute human waste by a factor of 100 or even more. As a result, we have created an immense wastewater problem, says Van Lier. The removal of pathogens from wastewater can also result in extremely high costs, while its necessity is disputable. For every potential case of hepatitis A infection, the United States spends between 3 and 30 million dollars per year on purification to eliminate the risk. This amount is completely disproportional to the costs of treating one patient with this disease.

Anaerobic purification

Traditional purification technology is based on adding air to the wastewater, which allows aerobic bacteria to do their purifying work. According to Van Lier, this method is completely obsolete; it requires a relatively large amount of energy and does not contribute to sustainable solutions. Within Wageningen University and Research Centre, far-reaching expertise has been developed in the area of anaerobic (oxygen-free) wastewater treatment. This method does not use any energy from fossil fuels. In fact, it produces energy because it generates methane. For developing countries, this consideration is extremely important for the choice of an applicable environmental technology. Much more complex, but equally essential, is that the water chain becomes much better organised, states Van Lier.

Examples include the deliberate reuse of urban wastewater for irrigation in agriculture within and around large cities in developing countries. This is an effective alternative for discharging wastewater to surface waters. It prevents environmental and health problems downstream from the city and provides income for the farmers. However, it also means that the relevant organisations and users need to communicate with each other, so that they can prevent situations such as that in the Jordan Valley. Farmers there use wastewater for irrigation, but have little knowledge of its composition, so they also apply fertilisers. As a result, dangerously high concentrations of nitrate occur in the groundwater.

Jac Niessen | Source: alphagalileo
Further information: www.wur.nl

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