In the last few decades, the focus of wastewater treatment facilities has been to collect household and industrial waste and treat them before being dispatched and used on the environment (gardens, agricultural farms, ranches, etc). Biosolids management was a concept alienated by most treatment facilities and even waste management policies because there is no real benefit derived from the substances that now compose biosolids.
Biosolids are the end-product of the treatment of sludge material coming from the process of treating household waste. The sludge material contains pollutants, pathogens, and other substances that have not been degraded during the treatment at the wastewater facilities. There was little to no attention given to the disposal of these components. What matters to advocates back then is to dispose the sludge in the most environment-friendly method as possible, which in some cases, meant dumping them in landfills.
Sludge, however, is wet and is very hard and expensive to transport because it does not compact very well. Aside from having a considerable amount of pathogens, organic pollutants, and heavy metals, it also gives off undesirable odors. That is why most treatment plants used to dump the sludge off to local farms and landfill sites. That is until the public started to notice how damaging this is to the soil. Such a practice is either banned or frowned upon in many locations.
What came next is a proper biosolids management process. This means that aside from the treatment the household waste undergoes, there is an additional treatment for the sludge that is invariably being produced by such waste. This treatment will then convert the sludge into dry biosolids that have huge positive benefits to the environment.
The treatment must be able to reduce the moisture content, volume of pathogens, and odors of the sludge material. There is also a need to increase the calorific value and the biological stability of the solid materials in the liquid waste.
The end-product is a dry biosolid material that can be reused in Waste-to-Energy (WTE) plants, coal-fired power plants, or cement kilns. It can also be used as an “organic” fertilizer for farms and ranches or as Class A land application. The most obvious benefit of turning the sludge into a biosolid matter is the reduction of handing and hauling costs. Since the sludge has been converted to dry biosolids, thanks to the proper biosolids management, its transportation is significantly lessened.