Q5 As for the recycling of sewage sludge,
what are the benefits of ash melting when compared with other recycling method?
As for the recycling of sewage sludge, there are several methods which are shown below:
- Composting
- Carbonization
- Material for concrete
- Melting
- Others
Composting and carbonization of sludge are suitable for small-scale facilities and for construction near agricultural areas where the end-product is expected to be used. However, sites generating sewage sludge aren’t necessarily sites that use the end-product. Therefore demand-supply and transportation distance should be considered.
Recently, utilization of sludge or ash for concrete material has become competitive. But this system depends mainly on the private sector which is susceptible to the economic situation at the time. On the other hand we need to keep treating sewage sludge regardless of the economic situation. This is one down falling involved with utilization for concrete material.
Compared with the aforementioned methods, a melting facility offers the following benefits.
- We can produce product(slag) at one site from sewage sludge to slag. Slag is being used more than ever for road-work material and other applications in Japan, so if distribution routes are fixed, demand will increase and utilization of slag subsequently is expected to expand more than ever.
