Closing the loops
The general prescription against increasing water quality deterioration is a paradigm shift in the way we use water and other resources. If we continue to use water as a medium for solving and transporting unwanted substances over long distances, be it human waste or industrial by-products, it will be increasingly difficult to maintain human and ecosystem health. By seeing waste as a resource, provided it is put in the right place, in right quantities and at the right time, several of the challenges listed above could be solved. To change the mindset and finding practical recycling solutions should, however, not be underestimated. One key to increasing the prospects for recycling is source separation. Currently most waste is mixed and placed in the same waste bin or sewer. With regards to wastewater there are several aspects that need consideration to allow for increased recycling: there are a range of sanitation options, different treatment levels for different types of reuse, the role of agriculture in the wastewater treatment cycle, policy and institutional frameworks that support reuse, suitable economic incentives and the ownership of wastewater. The most common use of wastewater is for irrigation. But the majority of this use is unregulated. Global estimates of the extent of wastewater irrigation range from 4 to 20 million ha. Many of the 200 million farmers who specialise in market gardening rely on raw or diluted wastewater. Practices range from the use of polluted surface water, to raw wastewater, to the piped distribution of secondary or tertiary treated wastewater. Use of wastewater for irrigation can be a way of maximising water use efficiency, as well as closing the water and nutrient loops to sustain and promote food production. When wastewater irrigation is well regulated, the agricultural sector provides the urban sector with a valuable environmental service. There were several practical examples during this year’s deliberations of how wastewater treatment plants are becoming “green factories”. By collecting food waste, waste water, fats and greases, and other organic wastes, treatment plants can be net producers of electricity, biofuel, fertiliser, and water for irrigation, industry and public consumption. A vast majority of the deliberations were held in an open, frank and respectful spirit. This does not mean that there always was a general agreement on the right solutions, but rather that there was an attentive dialogue on the pros and cons of the proposed solutions fromthe different perspectives.
