Composted Biosolids as a Fertilizer

Beneficial reuse of biosolids also includes using composted biosolids as a fertilizer. Biosolids are high in nutrients, particularly nitrogen and phosphorus. Given that phosphorus is required for all life to exist on this planet, and that there is a limited supply of phosphorus remaining, it is important to recycle phosphorus as we are able.

Biosolids can be composted on their own or together with poultry manure to produce a valuable fertilizer product. The advantage for the biosolids is that the composting process eliminates odour, potential pathogens as well as other emerging substances of concern present in raw biosolids. The advantage for the poultry litter is that the composting process eliminates potential pathogens as well as antibiotic resistant organisms. Given that next week (Nov 13-19) is Antibiotic Resistance awareness week, potential pathogens and microbial resistance is an important consideration.

Challenges with application of raw biosolids includes odour dispersion in the community, as well as a practical challenge of spreading the material consistently, particularly on grassland. Use of composted biosolids resolves many of the concerns, allowing phosphorus and other nutrients to be recycled.

Recycling biosolids, including the organic matter and nutrients, is an important step in encouraging a circular economy, where we understand that we are accountable for everything we produce or use, and that we recycle it in the best way that we can.