Abstract
Sewage sludge with concentrated amounts of nutrients, such as phosphorus in particular, has been projected to become a viable resource for use as fertilizer and compost in plant cultivation. Up to now, sewage sludge has been not used more frequently than animal manure compost. This paper summarizes the expectations and concerns regarding this anticipated trend toward application of sewage sludge compost. In addition, the paper refers to research examples that describe what type of sewage sludge compost would be required for its gainful utilization. Sewage sludge compost contains almost the same levels of organic matter and nutrients (nitrogen, phosphorus, calcium, etc.) as animal manure compost, excepting potassium. The amount of toxic metal(loid)s in sewage sludge compost is approximately the same as that found in animal manure compost. The level of insoluble phosphorus is higher compared to animal manure compost, but phosphorus in sewage sludge compost can be slow-releasing. It will be necessary to further evaluate the physicochemical properties of sewage sludge compost, taking into account the effects of coagulants and trace substances for the realization of its ultimate use. In addition, points and procedures for sewage sludge compost evaluation, as well as its quality standards need to be assigned and planned.
