Economic evaluation of sewer sludge treatment and disposal

According to cost-return analysis on long term basis the three technologies examined can be ranked as follows:
– The utilization of dehydrated sewer sludge in agriculture is the most favourable method of disposal, although its advantages are apparent only after 13 years of application.
– The second place goes to the agricultural utilization of liquid sewer sludge by injection techniques regarded as the basic method.
– The agricultural disposal of dehydrated sludge represents the most favourable approach if costs and returns to the entire society in parts at least are included into the analysis.