Making a Very Common Pollutant Useful

What Are Biosolids?

Biosolids are the organic remains after sewer sludge has been processed. Without further processing this waste material can take up precious space in landfills or be stored in expensive holding tanks. Sewage and waste water treatment plants have long handled biosolids and had to consider how to store or dispose of them. Until 1988 many coastal towns disposed of their biosolids by simply dumping them in the ocean. This was banned by the United States, Europe and Australia. Treating biosolids with certain chemicals can result in many uses. Land reclamation, agricultural needs, and landfill maintenance are just a few uses of these heavily organic materials.

Reclaiming Mined Lands

Heavily disturbed and contaminated soils in many mining and processing areas can benefit in many ways from biosolid distribution. A number of locations on the EPA’s Superfund list have shown how proper treatment of the area has minimized the damage done by the metals left behind. Chemicals naturally occurring in the biosolids as well as adding lime or wood ash have all been found to inhibit or convert these metals. The biosolids also greatly encourage plant growth to minimize soil runoff and allow new topsoil to develop. Similar results have been found at locations around the world.


Developing Agriculture


The organic nature of biosolids makes them an ideal material for fertilizing farmlands and forestry projects. Phosphorous, nitrogen, potassium and other nutrients are food for plant growth and all found in biosolids. The chemical make-up of biosolids also retains water minimizing the draw on local resources during droughts or dry seasons. Plant growth benefits are not limited to farms. Biosolids have been found to greatly encourage growth in trees such as douglas fir. This can minimize the recovery time needed in areas cleared by lumber efforts. On a smaller scale home gardens and landscaping projects can benefit from biosolids in many of the same ways larger farmlands and forests can.


Landfill Maintenance

Biosolids are used in a number of California landfills as alternative daily cover (ADC). Covering a landfill with biosolids at the end of each day controls contaminants and maintains a natural buffer between each day’s wastes. By treating the biosolids with certain chemicals odors can be minimized.

Environmental Benefits

All these uses of biosolids are beneficial to the health of the environment. Encouraging and accelerating plant growth has obvious benefits without requiring the transportation and use of hazardous chemicals. Using biosolids keeps them from taking up precious space in landfills. Some East Coast cities also burn biosolids to generate electricity, significantly lowering carbon dioxide emissions. While regulated and controlled the EPA has studied these uses and found them to be largely harmless to humans and other animals.
Given that the source of biosolids is largely the natural organic waste of humans, it is truly a renewable resource that can be utilized as long as we are on this planet.

This post was provided by Mary Blea, an environmentalist. She supports environmental corporations such as, an organic materials recovery firm, that use advanced technology to enhance the processing of biosolids.