January 01, 2014

Sustainable Land Application of Sewer Sludge as a Biosolid

Christopher W. Smith

Sustainability is not a fad. Neither is the land application of biosolids. It is no coincidence, then, that the two go hand in hand, and that their combination is growing in public acceptance. Limiting waste and developing methods for reusing waste are two of the fundamental tenets of the continually growing environmental movement. Because the land application of biosolids is likely to become only more prevalent over the years and decades to come, such application must be done in a safe and sustainable fashion.

Historically, domestic sewer wastes have been treated in wastewater treatment facilities and disposed of by landfill or incineration. In the past forty years, however, the focus on managing such waste streams and products has shifted from treatment and disposal to finding beneficial uses through sustainability practices. As a result, one waste product that has seen increased attention is biosolids generated from the treatment of domestic sewer waste. This article explores the practice of land application of such biosolids, its regulations, and what to expect in the years to come—particularly in the management of domestic sewer sludge.

Biosolids are primarily organic material produced during wastewater treatment. Despite significant efforts by wastewater treatment facilities to investigate the beneficial uses of biosolids, only a few recognized applications exploit the beneficial characteristics of biosolids. This may be due in large part to the perceived risks or other complications that community stakeholders inaccurately associate with biosolids. Inaccurate perceptions aside, the recognized applications of biosolids include recycling as compost, mine-site rehabilitation, brick manufacture, silviculture, agriculture, and potting-mix production. Notwithstanding these varied recognized applications, the leading application is the direct application to land or soil in order to restore organic nutrients and to replenish organic soil matter.

The process of land application is nothing new. Farmers have been repurposing animal waste for millennia. But land application of human waste in a refined manner is a relatively new process. Part of the refinement that makes up this new process is due to federal, state, and local regulations on the practice. Under those regulations, biosolids have been approved for use on agricultural land, forests, rangelands, or disturbed land in need of reclamation. As a result of those regulations, approximately half of the biosolids produced in the United States are being used to improve soil conditions.


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