River sediment removal methods include integrated sediment removal, direct suction sediment removal, and mud-water separation, etc. Specific methods are as follows:
1. Integrated Sediment Removal Methods: Employ environmentally friendly sediment removal techniques during the sedimentation process, considering both environmental protection and cost. Combine various sediment removal methods. Hydropulsion can disperse pollutants in sediments, so it should be avoided as much as possible or used only when river sediment pollution is light. Mechanical sediment removal using dredging ships not only fails to remove the floating sediment with high pollution load from the sediments but also stirs up the already settled pollutants during the cleaning process, leading to further pollution dispersion.
Therefore, it should be used in rivers with low silt pollution loads. Artificial erosion and deposition should also take into account the current status of river structure and sediment discharge conditions. Eco-friendly sediment removal should be vigorously promoted. When the sediment pollution load is very high, conduct eco-friendly sediment removal to reduce the pollution load to an appropriate range, and then proceed with hydraulic or mechanical sediment removal.
2. Direct Extraction Silt Removal: This is a new mechanical silt removal method suitable for urban river channels. The equipment primarily uses suction heads extending into the silt layer to create a vacuum, removing silt from the riverbed. A filter grate is added in front of the suction head to collect debris from the silt layer, separating it mechanically from the river. In addition to removing the vast majority of silt, this equipment can also remove heavily polluted silt from within the silt, and can be used in conjunction with sludge dewatering equipment. The device can be designed as both an on-water silt extraction vessel and an underwater silt removal robot, making it不受 limitations of river width, water level, and structures crossing the river.
3. Silt Separation: The river dredging process includes an additional step for dewatering and drying the slurry before transportation. The dredged silt primarily takes the form of slurry, with a moisture content typically ranging from 75% to 90%. Direct transportation would result in a massive volume and increase the dredging cost per unit of river.
Moreover, during transportation, mud slurry is prone to leakage, posing a threat to the environment along the transportation route. By adding a process of mud slurry dewatering and drying, the moisture content can be reduced to about 20%, turning the slurry into solid mud blocks, which significantly reduces the volume of transportation. This also facilitates transportation and greatly minimizes the negative impact on the environment of the transportation route. For the excess water generated during the dredging process, different methods should be adopted to treat the pollution level before discharging into the river.
