Utilization of Municipal Waste and Biosolids as Sources of Phosphorus for Land Restoration Projects

Waste disposal is one of the environmental challenges facing city authorities. However, waste contains considerable amounts of nutrients and organic matter required for plant growth. It is important to quantify the amount of waste generated and the quantity of nutrients that can be recovered. Further, the cost of applying the waste on land should be evaluated in order to make wise investment decisions. In Iceland, most of the waste generated is disposed without resource recovery. Therefore, the objectives of this study were to 1) quantify the amount waste generated in the Reykjavík capital area, 2) determine the quantity of phosphorus contained in waste generated 3) evaluate the cost of transporting the waste to nearby restoration sites and spreading it on the field. Operational data for 2015 was collected from wastewater and municipal waste operators in Reykjavík capital area. Phosphorus content in sewage sludge and municipal waste was calculated based on their dry matte and their typical phosphorus content reported in literature. The amount of waste generated, average distance to nearest restoration sites and recommended application rates formed the basis for calculating the cost of utilizing the waste in restoration. The cost of spreading the waste in the field was based on figures used by the Soil Conservation Service of Iceland. We found that phosphorus associated with wastewater treatment (effluent discharge and sludge) was 68%. Municipal waste accounted for 32% of the phosphorus generated. Phosphorus contained in all the waste was 400% higher than that used for land restoration. This phosphorus was, however, either landfilled or discharged into the ocean in waste. If this phosphorus was recovered, it would meet the phosphorus requirement for land restoration. The cost of utilizing the waste in restoration was estimated to be 140,000 ISK/ha (approximately $1,200/ha) with VAT included at 24%. This cost could be higher than using inorganic fertilizers. However, land application of waste is more economical than other waste treatment options. Furthermore, utilizing wastes reduces eutrophication in surface waters, and maybe most importantly, conserving the non-renewable phosphorus reserves. The study recommends that phosphorus recovery systems should be installed in wastewater treatment to improve phosphorus recovery. Legislation should be put in place to encourage waste utilization in land restoration.