Sludge disposal in Europe is affected by international trends and legislation, national and local situations, and of course economics. Some important trends are:
- Safe utilization of organic material and nutrients in the agriculture
- Sensitivity to energy costs
- Disinfection, especially by requiring batch heat treatment
- Restrictions and increased costs for landfill and incineration
- Increased public sensitivity to any hazard or nuisance
- Flexibility of end use for agricultural and non agricultural routes
- Insufficient capacity and inefficient operations of digesters
The situation is discussed in Denmark, Norway and the United Kingdom. The strength of each of these trends is different in each of the countries, however the trends are all represented in all of the countries and future sludge strategy must be able to cope with all of them.
Cambi thermal hydrolysis process (THP) is growing in the market as a process for solving very different local situations because it relates to all of the mentioned trends.
The first full scale THP was commissioned at HIAS Norway in 1995. Since that time there has been a rapid acceptance of THP as part of the digestion process because of the benefits of digestability, dewaterability and disinfection. In all of the projects described there was an economic payback for THP compared to conventional digestion.