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Impact of the 2006 WHO Water Reuse Guidelines on Global Water Conservation and Reuse

Congress: 2008
Author(s): Hillel Shuval
Head, Department of Environmental Health Sciences Hadassah Academic College-Jerusalem and Emeritus Professor of Environmental Sciences, The Hebrew University of Jerusalem, Israel- hshuval@vms.huji.ac.il

Keyword(s): Wastewater conservation and reuse, agriculture, quantitative microbial risk analysis-QMRA, WHO guidelines
Article:
AbstractINTRODUCTION: Some 50 countries in the world irrigate about 10 million hectares of crops with raw/ untreated wastewater producing about 12% of the worlds food crops. This practice provides vital work for hundreds of thousands of poor farmers and essential food for malnourished populations. However results in massive disease transmission. METHODS: We will analyse the impact of international and national wastewater recycling and reuse health guidelines on the global practice of wastewater reuse and their health and economic implications. We will also analyse the role of wastewater recycling and reuse as a strategy for water conservation in water short countries. FINDINGS: In 1933 the State Department of Health in California established the first legal health guidelines for wastewater reuse in agriculture. The standard set for unrestricted irrigation of vegetable crops normally eaten raw was 2.2 coliform bacteria/100ml of effluent. This is basically unachievable without very expensive high-tech treatment facilities. It was not based on epidemiological evidence or health-risk analysis studies but on the USA drinking water standard at that time which they felt provided a fail safe-no risk standard. Many countries throughout the world copied those standards but few were able to enforce them. With such strict and basically unenforceable regulations, governments found it difficult to take effective action to reduce health risks. This is a tragic case where demanding the very best prevents achieving the good. The WHO wastewater reuse guidelines of 1989, recommended that the quality of effluent for unrestricted irrigation of salad and vegetable crops could be 1,000 Fecal coliforms/100 ml. However, some countries such as the USA, which provides technical and financial assistance to many developing countries, have recommended much stricter and more costly health guidelines of zero F. coliforms/100 ml. Meeting these guidelines requires the construction of high-Tec treatment plants, favoured consulting engineers and equipment manufacturers. After years of research The WHO published, in 2006, an updated volume of the Guidelines for the safe use of wastewater, excreta and grey water based on advanced Quantitative Microbial Risk Analysis (QMRA) methods. The WHO concluded that the new QMRA risk assessment studies validated the 1989 WHO Guideline recommendation of 1,000 F. coli/100ml. The WHO risk assessment- QMRA methodology will be reported on and evaluated. The impact on wastewater recycling and reuse regulations on water resource conservation will be reported upon. CONCLUSIONS: These new 2006 WHO reuse guidelines provide developing countries with scientifically sound, more liberal ,economically feasible and more flexible health guidelines which should help in promoting safe wastewater reuse practice for better nutrition and better health. We will show that safe wastewater recycling and reuse can make a major contribution to water resource conservation in water short countries. For example in Israel in 2006 75% of the wastewater flow is recycled and contributes some 30% of the water used in agriculture. We also conclude that those countries that require much stricter standards do not have a rational health -benefit or cost-effective basis to justify the extra expenses involved in the extremely expensive additional wastewater treatment they require.
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