The increased demand for gas and petroleum, food crops, fish and large sources of vegetative matter mean that the global harvesting of carbon has in turn intensified. It could be said that mankind is mining nearly everything except its waste piles. Discussions held at a recent ISWA Beacon Conference on biological treatment of biowastes (Perugia, May 2008) suggest it is simply a matter of time until the significant carbon stream present in municipal solid waste is fully captured. In the meantime, the waste industry needs to continue on the pathway to increased awareness and better optimized biowaste resources.
While on-site rural composting is an age-old practice that we have come to rely on, other approaches are taking longer to develop and mature. For example, backyard composting remains in its infancy and will require more encouragement and public outreach to take off on a global scale. Large-scale anaerobic digestion, MBT, and windrow-type composting facilities have demonstrated various challenges in their use – mainly with handling, separation, processing and achieving quality end-products. With much of the product stream being returned to landfill as cover material or to thermal treatment processes as fuel, one wonders how these practices will fare in the long run.
Optimization of waste carbon may require widespread regulatory drivers (including strict limits on the landfilling of organic materials), public acceptance of the benefits of waste carbon products for soil improvements/crop enhancements, and more investment in capital facilities. In short, a significant effort will be required in order to capture a greater portion of the carbon stream and put it to beneficial use. From the standpoint of waste practitioners, further research and pilot programmes are necessary before the available carbon in the waste stream can be extracted in sufficient quality and quantities to create the desired end products. Other details need to be ironed out too, including measurement methods, diversion calculations, sequestration values and determination of acceptable contamination thresholds.
Reported tonnages of biowaste products are rising as our industry gets to grips with the contributing factors (by measuring, estimating or both). Because biowaste products generally feed the recycling numerator, recycling rates again rise, slowly but surely. Of course, we know that simply creating more biowaste products is not necessarily the answer. For example, while an organic product is seen as a good thing, a poor-quality compost can throw the benefits of the process into doubt. Encouragement comes in the form of the growing number of global facilities and operating experience, and increased interest by the private sector to manage the waste streams from collection and onward. This progress will almost certainly improve product quality, and with improved quality the products will find a market
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Greg Vogt is Managing Director of ISWA and ISWA editor of Waste Managment World
