Nowadays, heavy metal pollution in seabed silt is becoming more and more serious. In this study, a new disposal method of using dredged sludge mud mixed with quicklime, sand and cement to produce bricks was proposed. Taking the water absorption and compressive strength of unburned bricks as the target parameter, orthogonal experiments were carried out to evaluate the influence of various factors on the mechanical properties of bricks. The results showed that unburned brick had a strong curing effect on heavy metals. Therefore, the unburned bricks are very promising in the disposal of heavy metal polluted sludge and resource reuse.
In recent years, the construction of large-scale marine port and shipping projects in the world has been active, and the amount of dredged sludge has been increasing year by year, which brings a series of problems to marine management and environmental protection (Dong et al., 2016). The way out of dredged sludge has become a bottleneck restricting the development of coastal economy.
Marine dredged sludge is waste in the traditional sense. At present, the main disposal methods are reclamation and ocean dumping. The traditional method of dredging and reclamation often causes the phenomenon that the mud water diffuses to the outside of the cofferdam, causing secondary pollution problems. In addition, the problems arising from the disposal of marine dumping have become a bottleneck restricting the development of coastal areas. On the one hand, because some dumping areas are close to estuaries and offshore waters, they are biologically enriched and ecologically sensitive areas (Slimanou et al., 2020). Ocean dumping will affect the biological chain, destroy the ecological balance of the environment (Chen et al., 2017). And it also brings serious environmental problems. Ocean dumping areas are also becoming saturated due to years of use. On the other hand, the transportation distance of dredged mud becomes longer, which increases the difficulty of monitoring the dumping process. In order to save freight and shorten operation time, some dredgers may secretly discharge (Peng et al., 2017). This directly causes environmental pollution in the offshore waters because the navigation track is just in the position of the channel, and it will also cause repeated dredging of the channel engineering. The round-trip navigation of transport ships also increases the density of ships in the offshore waters and increases the difficulty of maritime traffic management (Cusido and Cremades, 2012).
