Sources of chemical fertilizers are quickly being depleted and fertilizer phosphate will run out before the end of this century. Long term environmental and food sustainability demands that nutrient rich organic end products of agricultural and food production and consumption, including agricultural and food wastes and manures, have to be recycled as fertilizers.
The other principal organic residual, biosolids, is the product of wastewater treatment practices, implemented for more than a century in developed countries and which are being put in place in developing countries at an accelerated pace. Let me first address the practices in Europe and North America as I have worked as a scientist on both these continents over a 40-year career. In 1993, the US put in place its regulations for treatment of sewage sludge. The US National Academy of Science concluded in 2002 there is no documented scientific evidence that these regulations have failed to protect public health. All 27 countries of the European Union, all states within the US and the provinces in Canada, and the developed countries in Asia, including Australia and New Zealand and many other countries support the sustainable recycling of organic fertilizer to the soil. China, India, Mexico and Brazil are heavily investing in water sanitation infrastructure and promote land application of biosolids.
Of all the nations of the world I only identified one, which does not support biosolids application as an organic fertilizer, Switzerland. But this is a special case. Switzerland’s very large factory farm activity produces an over abundance of animal manures, which more than adequately provide for the organic fertilizer needs of the country. Unlike other nations, Switzerland’s commitment to enrich the soil with organic fertilizers can be fully met through manures.
When the global practices of biosolids management are analyzed there are three principal options: recycling to soil as an organic fertilizer nutrient, incineration and landfilling. It is widely accepted that landfilling is not sustainable and more than a few nations have banned landfilling of biosolids. Incineration is not sustainable in terms of returning beneficial fertilizer nutrients to the soil. Incineration is sometimes practiced in regions of very high population density, where there is less access for land application or where excess driving distances for land application are not considered practical. Examples of nations where incineration is a more dominant are Japan, Switzerland and the Netherlands.
Globally, returning the nutrients of biosolids to the soil through land application is the dominant practice among the above options. Because of global demands for more sustainable environmental practices the proportion of biosolids being applied as fertilizer nutrients is increasing, while non-sustainable alternative practices are diminishing. Reported percentages of total biosolids applied to land as fertilizer are: Norway (95%), Australia (81%), Italy (69%), Slovakia (69%), New Zealand (66%), United States (55%), China (50% and growing), Hungary (39% and growing), Canada (33% and growing), European Union Average (40% and growing).
Owen P Ward, PhD
(Dr. Ward, co-inventor of Lystek’s technology, is Professor at University of Waterloo. He is former President of Canadian Society of Microbiologists and former Director of US based Society of Industrial Microbiology.)