Application of liquid biosolids

Australian farmers experience soil constraints both at the surface and subsurface which affect the ability of crops to absorb water and essential nutrients. Using nutrient rich organic waste materials including biosolids (sewage sludge) could be a more economically viable option to the rising costs of fertilisers. This solution also addresses the need for more efficient, socio-economically acceptable and environmentally sound disposal options for biosolids.

Safe and cost-effective disposal of sewage sludge generated from the wastewater treatment is one of the major environmental challenges facing the water industry and communities today. Cities in Australia and elsewhere generate high volume of wastewater and solids, which results in high environmental footprint. There is an urgent need to develop, evaluate and implement alternative and diversified options for biosolids management and utilisation.

Subsoil injection of liquid organic wastes including biosolids, animal manures and food industry wastes has been practiced in Europe and North America since the 1980s, but it is not common practice in Australia. This project will explore the agronomic benefits and environmental effects of direct subsoil injection of sewage sludge taken from wastewater lagoons. It will be targeting improvements in soil structure and fertility as a result of subsoil injection of sewage sludge.

This project will involve research, development and demonstration (RD&D) processes to study the agronomic benefits and environmental risks of injecting wastewater sludge into subsoil. The project will be conducted at Longwarry Water Recycling Plant in Victoria for three years, and will investigate the factors such as time, capital, infrastructure, machinery, cost, labour, energy and environment associated to the operation. The sludge will be applied at the Longwarry RD&D site after pre and post treatment processes and a summer sorghum crop will be established for two consecutive seasons to study the agronomic value of injected sludge in subsoil.