Professor Nanthi Bolan of CRC for Contamination Assessment and Remediation of the Environment and University of South Australia told CleanUp 2013 in Melbourne today that the solid waste left over after sewage treatment could be used to curb carbon emissions and create more fertile soils.
Annually, Australia stockpiles about 70,000 tonnes of biosolids from urban sewer systems. Instead of being seen as mere waste and excrement, these biosolids can be viewed instead as an untapped environmentally friendly resource.
In fact, biosolids can be applied to agricultural soils and revegetation projects to lock up carbon and boost plant growth. Agricultural soils stand to gain the most from these biosolids.
The nitrogen and other nutrients from biosolids contribute to crop growth, and the organic matter in the biosolids improves soil structure. It also traps non-degradable forms of carbon so that they will stay in the soil for ages.
Some argue that biosolids are costly to transport to the area in which they will be used, but experts have calculated that their benefit to the soil, boosting fertility and increasing carbon retention in the soil, far outweighs the cost of transport.
Since biosolids are made of human waste, they contain major nutrients like nitrogen and phosphorus as well as micronutrients and trace minerals. Experts agree that recycling waste through agriculture might actually increase the nutritional quality of food in Australia.