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|Name of Technology||Production of Activated Carbon from Sewage Sludge and Cost Reduction of Sludge Treatment by Effective Utilization|
|Technology Owner||Kawasaki Heavy Industries, Ltd.
Kimura Manufacturing Co., Ltd.
|General Description||This technology aims to encourage the recycling of sewage sludge by producing activated carbon from sewage sludge via drying, carbonization and activation processes that create a micropore structure, and by encouraging the use of the activated carbonized products.
Another goal of this technology is to implement it at small wastewater treatment plants as well, by modularizing the activated carbon production technology so that it can be assembled at users Eplants at lower cost.
|Components of Technology||The system comprises the following three main equipment components.
 Dryer module: Drying unit and its ancillary equipment for drying dewatered sludge
 Carbonizing furnace module: Externally heated carbonization-activation screw unit and its ancillary equipment for producing activated carbonized products from dried sludge
 Heat recovery device: Heat exchanger for recovering heat from the combustion gas produced by the carbonizing furnace module and transferring the recovered heat to the circulating dryer exhaust produced by the dryer module
Flowchart of activated carbonization
Dewatered sludge is converted into activated carbonized products through the processes shown below.
Dewatered sludge is fed to the drying unit in the dryer module via a sludge pump and is dried to a moisture content of 10% to 20%. (Drying process)
The dried sludge is then fed to the carbonization-activation unit in the carbonizing furnace module. In the screw casing which is heated to a high temperature, the dried sludge undergoes carbonization in the front section and then activation in the rear section, becoming activated carbonized products. (Carbonization-activation process)
The present system produces dryer exhaust from the dryer module and combustion exhaust from the carbonizing furnace module. The dryer exhaust is divided into circulating dryer exhaust and excess dryer exhaust.
These gases flow as follows.
The excess dryer exhaust is cleaned by the scrubber, undergoes a hot deodorization process in the carbonization-activation unit, and is released to the atmosphere with combustion gas.
The circulating dryer gas returns to the dryer module after being heated by the combustion exhaust in the heat recovery device.
|Features of Technology||1. System Features
(1) Reduced construction cost
When modularized for assembly at the user's plant, the three main equipment components can substantially reduce the construction cost.
(2) Reduced operating cost
The following three features of the system raise the total thermal efficiency and thus reduce the operating cost.
The dryer exhaust is steam evaporating from dewatered sludge. By using the steam as a heating medium for recovering heat from the hot combustion gas via the heat recovery device, thus eliminating the need for a hot-air source required by the conventional drying unit, the system improves the thermal efficiency and reduces the operating cost.
1.3.3 Product Features
Properties of activated carbonized products
Activated carbonized product and its microphotograph
|Evaluation of Technology||
This technology was developed in the LOTUS Project (Lead to Outstanding technology for Utilization of Sludge Project) and evaluated and reviewed by the Sewerage Technology Development Project Committee under the Ministry of Land, Infrastructure and Transport in Japan in 2007.
Note: This technology was developed by Kawasaki Environmental Engineering Co., Ltd. and Kimura Manufacturing Co., Ltd., and evaluated in 2007. Kawasaki Environmental Engineering Co., Ltd. has been consolidated into Kawasaki Heavy Industries Ltd. since 2010.
|Contact Information||Industrial Plant Sales Department (Chemical
Plant), Plant & Infrastructure Company,
Kawasaki Heavy Industries Ltd.
For inquiry: http://www.khi.co.jp/cgi-bin/other-q1_e.cgi?form-type=ind-plant&ca_no=30