Through the examination of various routes for the disposal of sludge from wastewater treatment plants, three inter Walloon companies namely AID and the INASEP INTRADEL considering the transport of sludge from wastewater treatment plants by means of 'Water for structures located along waterways. These inter-turned to the section of transport service to ANAST:
- To analyze the feasibility of an efficient transport of sludge through water initially from different treatment plants in operation or build in Wallonia.
- To establish the conditions for the feasibility of such transport.
The tables on the next page show the works in which the sludge will be produced (Table 1) and incineration (Table 2). The transportation of sludge should be organized between production sites and those of incineration of sludge.
The analysis of the problem has identified the following factors as essential to the achievement of transport concerned:
- The strategy for sludge storage.
- The frequency of collection of sludge.
- The characteristics of the waterway concerned.
As the carriage itself, after having identified the parameters defining the scenarios, two scenarios were selected and evaluated against the parameters defining the scenarios and endpoints scenarios below:
- The cost of operation.
- The impact on the environment.
- The time of implementation.
Conclusion of study
The study showed that the transport of sludge from wastewater treatment plants is technically feasible. Simply use the material as suitable for handling, storage and the transport itself. Several transport scenarios were analyzed and two were selected.
For both scenarios, only one type of transportation equipment is considered: it is the transportation by tankers. The container transport has been rejected.
The first scenario calls for the use of one boat to transport sludge and two sites for the incineration of sludge while the second scenario calls for the use of two vessels for the transportation of sludge and a single site for incineration.
Regarding the implementation of the transportation itself, it should emphasize the importance of the parameter 'frequency of collection sludge'. Indeed, it is this parameter that determines the quantity of sludge to be collected per site, the capacity of the transport unit, the storage capacity to be installed on the sites of production and productivity of loading / unloading sludge. A collection frequency too low leads to store large quantities of sludge on the different production sites with the risk of fermentation of the sludge, which then become very nauseous causing environmental pollution. Frequencies too low results in the use of transport equipment of greater capacity, means of loading / unloading more consistent, etc.. The frequency of collection of sludge must be a compromise between all these factors so as to enable efficient transport both as regards the capacity of materials used that time of handling (loading / unloading).
Regarding the two scenarios used, the cost of operating result shows an advantage in the first scenario (use of one boat and two incineration plants) compared to the second scenario (using two boats and a single-site incineration). This suggests that the new incinerator sludge should be built on the site Oupeye. Scenario 5 is the one with the best assets to an embodiment of the transport of sludge by water. The best solution is one that avoids the transportation of sludge produced at the station of Liège Oupeye.
Regarding the protection of the environment, the study showed that the shift from road to inland water transport sludge reduces the number of trucks on the roads of Wallonia, while it significantly reduces the amount of CO released into the wild in a ratio of one to four in favor of the waterway from the road. It should be noted however that the implementation scenarios river is subject to the conclusion of contracts attractive to boatmen, valid in the long term to attract them to this type of activity.
For more information about this study please contact the transport section of the service ANAST