Thirty years ago, thousands of American cities dumped their raw sewage directly into our nation’s rivers, lakes, and bays (gross!). Today, because of improved wastewater treatment (as well as strict Federal and state standards), the treated leftovers from wastewater treatment (or biosolids) can be safely recycled.
Sewage sludge is created through the treatment of domestic wastewater by sewage treatment facilities. The treatment of sewage sludge is a very long and thorough process to make sure that hazardous contaminants are removed. Sometimes this process starts long before wastewater even gets to a wastewater treatment plant, with pretreatment at some industrial facilities. Once the wastewater reaches the plant, the sewage goes through physical, chemical and biological processes which clean the wastewater and remove the solids. The treatment processes sanitize wastewater solids to control pathogens (disease causing organisms, such as certain bacteria, viruses and parasites) and other organisms capable of transporting disease.
This stabilization treatment includes such processes as digestion, lime stabilization, pasteurization and composting, which change the chemical and physical characteristics of the wastewater solids to a biosolids product that may safely be applied to the land. Safe biosolids can even be made from residential septage (a nice term for human or household waste from septic tanks or cesspools) when treated and processed correctly. It turns out that the end product of wastewater treatment is an extremely nutrient-rich resource – what a transformation!
Once it is ensured that the resulting biosolids meet specific quality criteria, they can be safely recycled and used as fertilizer to sustainably improve and maintain productive soils and stimulate plant growth. Biosolids can reduce a farmer’s costs and replenish the organic matter that has been depleted over time. Plus, the organic matter improves soil structure by increasing the soil’s ability to absorb and store moisture. Some biosolids are applied to the land as a liquid, while others have water removed from them and are a consistency similar to wet soil. Still other biosolids are in the form of compost material and pellets.
Every state in the United States uses biosolids in some fashion. Farmers and gardeners have been using biosolids for years. Biosolids have been applied to reclaimed mining sites to promote quicker vegetation growth. But, despite their benefits, only 50% of the biosolids produced are used and they are only used on one percent of America’s agricultural land. Unused biosolids end up in landfills where this valuable fertilizer goes to waste. Check out who your state contact for biosolids is and find more information on biosolids.
The National Biosolids Partnership (NBP) advances environmentally sound biosolids management practices. The program is operated by the Water Environment Foundation (WEF), in collaboration with the National Association of Clean Water Agencies (NACWA) and local and regional biosolids management organizations across the U.S. and Canada with support from the EPA. The NBP serves as the information clearinghouse on effective biosolids practices and offers an Environmental Management System (or EMS) based certification program that requires participating organizations to go beyond regulatory requirements.
Do you have any innovative ways to recycle waste? Perhaps you have a compost pile? Share your ideas!