Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Sustainable conversion of heavy metal pollution of dredged sludge into unburned brick: Mechanism andcharacterization
Zhichao Shen1, Xin Liang1, Xuyuan Zhao1*, Xiaodan Mao1, Jifu Yin1, Feixin Wang1
1National Engineering Research Center of Dredging Technology and Equipment, Shanghai, China

which increases the difficulty of monitoring the dumping process. Inorder 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 theoffshore waters and increases the difficulty of maritime trafficmanagement (Cusido and Cremades, 2012).

ABSTRACT
Nowadays, heavy metal pollution in seabed silt is becoming more andmore 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 ofunburned bricks as the target parameter, orthogonal experiments werecarried out to evaluate the influence of various factors on themechanical properties of bricks. The results showed that unburned
brick had a strong curing effect on heavy metals. Therefore, theunburned bricks are very promising in the disposal of heavy metal
polluted sludge and resource reuse.

At present, the most likely method for large-scale disposal of marine
dredged mud is chemical solidification. The curing principle is mainly
to use the hydration reaction of the cured material itself to combinewith water to form a hydration product. Hydration products are filled or
supported among the sludge particles (Yang et al., 2021), thereby
forming the overall strength of the cured body. This method has theadvantages of uniform soil quality after solidification, fast
consolidation speed, and large bearing capacity. The use of silt to makebricks can not only solve the problem of dredging the silt in the river,
but also solve the contradiction between the production and protectionof cultivated land in brick-making enterprises. Most building materials
are derived from natural non-renewable mineral raw materials(Mezencevova et al., 2012). Only a small portion comes from industrial
waste. The brick and tile industry is the industry that consumes themost land resources. At present, clay bricks can still account for about
50% of the market share of wall materials. It is estimated that morethan 16,473 acres of agricultural land are destroyed each year.
Therefore, it is necessary to carry out relevant research on the use ofmarine dredged mud to make bricks.

KEY WORDS: Dredged sludge, heavy metal, bricks, resource
reuse
INTRODUCTION
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 tomarine management and environmental protection (Dong et al., 2016).
The way out of dredged sludge has become a bottleneck restricting thedevelopment of coastal economy.
Marine dredged sludge is waste in the traditional sense. At present, themain disposal methods are reclamation and ocean dumping. The
traditional method of dredging and reclamation often causes thephenomenon that the mud water diffuses to the outside of thecofferdam, causing secondary pollution problems. In addition, theproblems arising from the disposal of marine dumping have become abottleneck restricting the development of coastal areas. On the one
hand, because some dumping areas are close to estuaries and offshorewaters, 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,

MATERIALS AND METHODS
Experimental materials
Dredging sludge were used in a certain sea area of the East China Seaand dredging sludge were dewatered by a belt filter press. The averagemoisture content of undisturbed dredged mud is 78%. The organic
matter content is 1.56%. CaO and other chemicals were provided byShanghai Titan Technology Co., Ltd, China. Cement and sand were916