Thermal Drying As Biosolids Processing System



Do you know that in many communities across America, biosolids processing remains to be a frowned upon method of garbage disposal and sewage sludge handling? The disposal and the transportation of biosolids remain to be one of the biggest challenges of every municipality in the United States. Public opinion of biosolids as a long-term solution to the waste problem is in slow development. Though biosolids should be favorable long-term solution to the waste problem, many communities are still unwelcoming to the processes.

There is one technology that has risen to the challenge in recent years. That technology is called thermal drying, and it is not a very uncommon term in the environment protection industry. Thermal drying processes vary by nature, but the basic definition is the application of heat to evaporate water from biosolids. It drives off the moisture that is still contained in dewatered biosolids cake. The process can reduce water content by up to 10 percent or less.

The thermal drying process has a double purpose, too. Since the product or the biosolids are heated, pathogens contained in the end product are reduced and it can therefore meet the EPA standards for Class A or Exceptional Quality biosolids.

These dried biosolids can then be used as fertilizer on soil or as fuel. It effectively reduces and eliminates the cost of disposing biosolids. For many of you who don’t know, the drying processes are highly sustainable methods for meeting environmental standards and reducing disposal costs. For safety purposes, the maximum temperature that the biosolids are subjected to is around 350 degrees Fahrenheit. After the process, the end product is Class A biosolids that are ready to be applied on land.

Cutting costs of transportation and disposal are not the only advantages of thermal drying. It could significantly reduce the cost of using natural gas because it furnishes fuel in the generation of heat. Many facilities in the past have relied solely on natural gas as the heat source for the process. When natural gas plays into the equation, it is very difficult to control the cost of the process because the price of natural gas is dependent on a very volatile market.

Even with the natural fluctuations in the cost of gas, the disposal and the transportation of waste will still exceed the money spent on managing and running a biosolids treatment plant. This, of course, is a focus for many treatment plants—the improvement of gas-fired drying systems that should be less dependent on natural gas.

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