Question

Of the major options for handling sewage sludge, which may be safest?

Answer 1

The safest option for handling sewage sludge includes anaerobic digestion in heated and enclosed tanks to reduce volume and destroy pathogens, with the final material potentially used as fertilizer.

Step-by-step explanation:

When dealing with sewage sludge, the aim is to make it safe for the environment and public health. One of the safest ways to handle sludge is through a process called anaerobic digestion. In this process, sludge is placed in digesters, which are heated and enclosed tanks. Inside these digesters, the material is broken down by anaerobic bacteria over 20-30 days. This reduces the volume, minimizes odors, and destroys pathogens. The resulting biogas, primarily methane, can be captured and used as an energy source. Furthermore, the treated sludge can be used as a fertilizer on crops, provided it has been thoroughly tested and cleared of any hazardous contaminants.

Answer 2

Anaerobic digestion is likely the safest method for handling sewage sludge, as it reduces volume and odors, destroys pathogens, and produces biogas that can be used as an energy source.

Step-by-step explanation:

Of the major options for handling sewage sludge, anaerobic digestion may be the safest. This process involves the use of bacteria in digesters to decompose the sludge in the absence of oxygen, which reduces the volume, odors, and the potential for disease causing organisms. The biogas produced, mainly methane, can be harnessed as an energy source, and the resulting digested solids can potentially be used as fertilizer after thorough testing for contaminants. Other methods such as incineration or landfill disposal carry greater environmental risks or fail to make use of the potential resources within the sludge.