CN210419687U

CN210419687U - Sea sludge resource utilization system

Info

Publication number: CN210419687U
Application number: CN201921116006.XU
Authority: CN
Inventors: 余广炜; 汪刚; 汪印; 余铖; 王玉
Original assignee: Institute of Urban Environment of CAS
Current assignee: Institute of Urban Environment of CAS
Priority date: 2019-07-17
Filing date: 2019-07-17
Publication date: 2020-04-28
Anticipated expiration: 2029-07-17

Abstract

The utility model belongs to sea area desilting and solid waste resource field disclose a sea silt resource utilization system, include: the device comprises a hydrocyclone, a No. 1 dewatering device, a sludge biochar storage bin, a conditioning tank, a No. 2 dewatering device, a forming granulator, a dryer, a roasting machine and a cooling device; the underflow outlet of the hydrocyclone is communicated with the inlet of the No. 1 dewatering device, the top overflow port of the hydrocyclone and the outlet of the sludge biochar storage bin are communicated with the inlet of the conditioning pool, the outlet of the conditioning pool is communicated with the inlet of the No. 2 dewatering device, the solid phase outlet of the No. 2 dewatering device is communicated with the inlet of the forming granulator, and the forming granulator, the dryer, the roasting machine and the cooling device are communicated in sequence. The utility model provides a problem that sand mud mixes among the current desilting sea mud technique to mud biochar has realized that sea silt is high-efficient to dewater desalination and full process utilization as the conditioner, and is continuous high-efficient, and degree of automation is high, and the cost is lower, no secondary pollution.

Description

Sea sludge resource utilization system

Technical Field

The utility model belongs to sea area desilting and solid waste resource utilization field, concretely relates to sea silt resource utilization system.

Background

The creeping of the sea silt along with the ocean current can block the channel, thus aggravating the channel dredging cost; the sea sludge promotes the eutrophication of seawater, and can cause the silting or even the abandonment of a seawater farm when the seawater is serious; construction of engineering facilities in coastal regions also produces large quantities of waste sea sludge. The continuously regenerated sea sludge brings great difficulty and hidden danger to the construction and maintenance of offshore environment and engineering facilities, not only causes new environmental problems, but also wastes the potential application value of the sea sludge. Therefore, with the large-scale development of water conservancy and water environmental management engineering in China, a large amount of dredged sludge is generated every year. The problem to be faced is how to effectively and reasonably treat and develop and utilize the excavated seabed sludge. Dredged sludge mainly takes fine-grained soil as a main material, is rich in organic matters and various pollutants, and is usually scattered to form a slurry state with high water content due to disturbance of dredging construction, and essentially belongs to solid waste with high water content. The high water content, fine particles and different degrees of pollution of the dredged sludge are difficult points which cause the dredged sludge to be difficult to treat in a large scale: (1) high water content: the sludge is deposited in still water or slow running water environment, is formed by biochemical action, is low-strength soil which is loose in connection and is filled with water in pores, and the in-situ water content of the surface sludge is usually 100-150%; in the environment-friendly dredging project,the sludge is disturbed into a slurry state by means of cutter suction, pump pumping or hydraulic excavation and then is conveyed to a sludge piling field by a pump; 1m³After the sludge is dug out, the volume is increased by 4-6 times, the mass fraction is only 10-20%, and the sludge is in a flowing state; (2) the content of fine particles is high: the sludge mainly comes from particles of water and soil loss, point source and surface source discharge and atmospheric dust fall, and the components mainly take fine-grained soil as the main component; the fine silt particles are mainly secondary clay minerals and mainly comprise SiO₂、Fe₂O₃、A1₂O₃CaO, MgO and Na₂O, etc.; the clay minerals have large specific surface area and adsorption capacity, and have strong binding force with water, so that the sludge is difficult to dehydrate; (3) contains the following pollutants: when sludge particles are deposited in water, the surface of the particles usually has charges which can adsorb N, P, heavy metals and many macromolecular functional groups in the water to the surface of the particles, so that the sludge is polluted by organic matters and nutrient salts to different degrees.

Offshore sites are typically disposed of by marine dumping, while inland sites are typically stockpiled in yards. Soil components in the dredged sludge can be used as a filling material for a low-lying area on the sea or land, and the foundation strength is improved by blowing and filling the sludge in a certain area and then carrying out a vacuum or stacking consolidation method. The method is applied in many countries and regions in the world, and for example, a method of filling by blowing and then reinforcing the foundation is adopted in construction of many marine artificial islands and airports in Japan, Singapore, the Netherlands. The dredged mud hydraulic filling land-building method has the main problems that the foundation is weak after hydraulic filling, and construction machinery is difficult to enter for a long time; in addition, the sludge is composed of fine particles, the permeability is poor, the inserted drainage channel is easy to block, the consolidation needs a long time, and the process of recovering the use after the natural evaporation and consolidation sedimentation form the land needs to last for several years to dozens of years. Therefore, the method for dredger fill of sea sludge to build land is suitable for projects with relatively spare construction periods. On the other hand, the main reason why the sea sludge is difficult to be recycled is that the sea sludge contains a large amount of salt, and the salt content is about 3-5%. The sea sludge can be recycled only by removing the salt in the sea sludge. The salt in the sea sludge is mostly soluble salt such as sodium chloride and the like, and is dissolved in the water in the sea sludge, so that the water in the sea sludge is squeezed out, and the salt content of the sea sludge can be reduced. At present, only in-situ drainage methods such as preloading, vacuum preloading and the like exist, but the treatment time is as long as several years. The leaching desalination method is mainly characterized in that atmospheric precipitation or irrigation is adopted to directly leach the saline-alkali soil, and due to the fact that the permeability coefficient of the saline-alkali soil is large, leaching liquor seeps down quickly in the leaching process and penetrates through the stratum quickly. Therefore, a large amount of water is consumed in the in-situ leaching process, so that not only is the water resource wasted, but also the leaching and desalting time is relatively long. In conclusion, the water content of the sea sludge is high, an economically feasible dehydration and desalination scheme is required to be found before treatment, the sludge volume is reduced, and reduction is realized; meanwhile, the optimal treatment scheme of the sea sludge is to realize resource utilization, and the sea sludge is taken as a raw material of other products, so that the realization of resource recycling is the inevitable direction of sea sludge treatment.

On the other hand, with the rapid development of the social economy and urbanization process of China, the scale and the sludge production amount of urban sewage treatment plants are continuously increased, and the sludge treatment pressure is higher and higher. The sludge pyrolysis technology is widely concerned and applied because the sludge reduction and the harmlessness can be quickly realized, but the research on resource utilization of the sludge pyrolysis biochar which is a terminal product obtained after the sludge pyrolysis is insufficient, and the popularization and the application of the process are seriously restricted.

CN105731758A discloses an integrated device and method for dewatering, solidifying and treating marine dredging sludge, the dredging sludge is sucked onto a dredger by the dredger, the dredger reaches an offshore treatment platform, the dredging sludge is conveyed into a mud-water separation device, the dredging sludge is centrifugally dewatered by the mud-water separation device, the dewatered tail water is conveyed to a tail water treatment device for treatment, the concentrated sludge is conveyed to a solidifying device, the solidifying material in a solidifying material tank is conveyed to the solidifying device together, the concentrated sludge and the solidifying material are fully stirred to obtain solidified soil, and the solidified soil is conveyed to a sea filling area by the dredger for sea filling. CN107814474A discloses a river sludge treatment method, which comprises the following treatment steps: (1) mechanically dewatering the sludge to a water content of less than 15%; (2) adding microorganisms into the sludge treated in the step (1), stirring for reaction, and carrying out air blasting and air exchange until the water content of the sludge is lower than 5%; (3) and (3) taking the sludge treated in the step (2), and performing electroosmotic dehydration to constant weight, so that the effect of improving the dehydration rate is achieved. The method adopts electroosmosis dehydration, and has high cost. CN1843987A discloses a construction method of sludge solidified soil, which comprises the following steps: (1) firstly, dewatering the dug sludge to ensure that the water content of the sludge is 40-60% by weight and approaches to the liquid limit; (2) adding cement and fly ash into the dewatered sludge; wherein the adding amount of cement is 50-100 kg and the adding amount of fly ash is 50-150 kg in each cubic meter of sludge; (3) then stirring for 30-80 seconds to uniformly mix to obtain solidified silt soil; (4) and stacking the solidified silt soil for 2-3 days, enabling the solidified silt soil to continue to be subjected to solidification reaction, having early strength and being capable of being mechanically paved, namely paving the solidified silt soil on a roadbed, a dam or a depressed place in a layered mode, and rolling the solidified silt soil in a layered mode by using a machine. CN105622061A discloses a novel method for making bricks by using beach sludge, in particular to a method for making bricks by using coastal beach sludge and beach sludge entering a sea mouth as raw materials, which comprises the steps of silt mining, washing, sludge slurry centrifugation, sieving, crushing, stirring and blank making, predrying and firing. CN106007295A discloses a silt anaerobic cracking system for preparing charcoal mud and a process, the system comprises a mud suction device, an impurity removal device, a dehydration device, a material conveying device, an anaerobic cracking carbonization device, a water inlet device and a water discharge device, wherein the anaerobic cracking carbonization device is used for directly preparing the sea silt into cracking charcoal. However, the above method is relatively complex in process and high in cost. CN102849917A discloses a continuous on-line filter bag type dehydration method for lake and river channel dredging sludge, which realizes rapid dehydration by adding PAC and PAM for coagulation reaction. CN102020407A discloses a silt curing agent, in particular a physical curing agent for realizing rapid dehydration of silt, changing the flowing state of silt and improving the strength, especially the early strength, of the cured soil. CN102020407A discloses a method for quickly dehydrating sludge, which utilizes super absorbent resin to realize quick dehydration of sludge, improve the flowing state of sludge, reduce the mixing amount of curing agents and improve the early strength of cured soil. However, none of the above methods relate to the use of sludge biochar as a sea sludge conditioner, let alone to the synergistic utilization of both. In addition, the scheme of applying the sludge pyrolytic biochar to the sea sludge recycling is few in domestic and foreign research and report.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a new sea silt resource utilization's system in order to overcome the problem that has sea silt dehydration difficulty, cycle length, inefficiency and difficult resource utilization when adopting prior art to handle sea silt.

Specifically, the utility model provides a sea silt resource utilization system, wherein, sea silt resource utilization system includes: the device comprises a hydrocyclone, a No. 1 dewatering device, a sludge biochar storage bin, a conditioning tank, a No. 2 dewatering device, a forming granulator, a dryer, a roasting machine and a cooling device; the underflow outlet of the hydrocyclone is communicated with the inlet of the No. 1 dewatering device, the top overflow port of the hydrocyclone and the outlet of the sludge biochar storage bin are communicated with the inlet of the conditioning tank, the outlet of the conditioning tank is communicated with the inlet of the No. 2 dewatering device, the solid phase outlet of the No. 2 dewatering device is communicated with the inlet of the forming granulator, the outlet of the forming granulator is communicated with the inlet of the dryer, the outlet of the dryer is communicated with the inlet of the roasting machine, and the outlet of the roasting machine is communicated with the inlet of the cooling device.

Further, 1# dewatering device's top is provided with fresh water spray set just sea silt resource utilization system still includes the buffer pool, fresh water spray set be used for by 1# dewatering device generates the solid phase result spray rinse, 1# dewatering device's filtrating export with the entry intercommunication of buffer pool, water in the buffer pool is as fresh water spray set's circulating water.

Further, the cooling device is directly cooled by air, and an air outlet of the cooling device is communicated with a fuel inlet of the roasting machine, so that air preheated by the cooling device is pumped into the roasting machine to be used as air required by fuel combustion.

Further, a flue gas outlet of the roasting machine is communicated with an energy source inlet of the dryer, so that flue gas generated by the roasting machine is used as energy source for drying by the dryer.

Further, the sea sludge resource utilization system further comprises a tail gas purification device, and an energy outlet of the dryer is communicated with an inlet of the tail gas purification device.

Further, the No. 1 dehydration device is a vacuum belt filter; the vacuum degree of the vacuum belt filter is more than 0.03 MPa.

Further, the No. 2 dewatering device is a plate-and-frame filter press or a high-pressure belt filter press.

Further, the buffer tank and the hardening and tempering tank are respectively and independently a common steel mud tank or a concrete mud tank provided with a stirring device.

Further, the forming granulator is a disc granulator, a roller granulator, a double-roller forming machine or an extrusion granulator.

Further, the dryer is a crawler-type dryer, a roller dryer or an oven.

Further, the roasting machine is a rotary kiln or a belt type roasting furnace.

Further, the cooling device is a belt cooler or a roller cooler.

Further, the tail gas purification device is a wet flue gas purification device, a semi-dry flue gas purification device or a dry flue gas purification device.

The utility model has the advantages as follows:

the utility model firstly pumps the sea silt slurry liquid into the hydrocyclone for separation, and coarse-grained sand obtained by the hydrocyclone separation can be used as building material after dehydration and optionally fresh water washing, thereby solving the problem of sand-mud mixing in the prior desilting sea mud technology and realizing the high-efficiency desalination and resource utilization of the coarse-grained sand; the fine-particle sludge slurry obtained by the separation of the hydrocyclone is extremely difficult to dewater, and the sludge biochar can form a good drainage channel inside the sludge to form a micro framework to improve the pressure transmission effect inside the sludge, increase the pores of the sludge and promote the formation of the 'micro drainage channel' in the soil body, so that the pore water pressure dissipation of the sludge in the filter pressing process is accelerated, the dewatering efficiency of the sludge is greatly enhanced, and the desalting effect is improved. In addition, the sludge biochar is alkaline, and the fine-particle sludge slurry is mixed and tempered by using the sludge biochar as a conditioner, so that elements such as N, P, K in the sludge biochar can be easily absorbed by plants, the fertility of the sea sludge is enhanced, and the nutrient soil is looser to be beneficial to crop absorption. Therefore, when the content of heavy metals in the solid phase of the sludge obtained after mixing, stirring, tempering and dewatering meets the national agricultural sludge pollutant control standard GB4284-2018, the sludge can be directly used as soil for landscaping and flower planting, and each index of the obtained nutrient soil is close to the national organic fertilizer standard NY 525-2012. Moreover, the sludge solid phase can be directly used for greening in seaside saline-alkali soil, and the porous carbon contained in the sludge solid phase can fully play two roles: the method has the advantages that the fresh water required by greening plants is well kept, the effect of 'ecological conservation' is realized, the rapid loss of water of the plants after watering is avoided, and the problem that sea silt is difficult to treat can be solved on the spot; secondly, salt in the seaside saline-alkali soil is prevented from permeating upwards to influence plant growth, and the effect of pressing salt is achieved. When the content of heavy metals in the solid phase of the sludge obtained after mixing, stirring, tempering and dewatering exceeds the agricultural sludge pollutant control standard GB4284-2018, the sludge can be further prepared into ceramsite through the processes of granulation, drying, sintering and cooling, effective elements such as iron, aluminum, silicon, calcium, carbon and the like in the sludge biochar are fully utilized to adjust the components of the sea sludge, other components do not need to be additionally added, the way of recycling the sea sludge is expanded, a green product scheme can be provided for the sea sludge dewatering product, and a low-cost raw material can be provided for preparing the ceramsite. Furthermore, the utility model discloses can realize that sea silt dehydration utilizes with the full flow for the process is continuous high-efficient, and degree of automation is high, and the cost is lower, and no secondary pollution is little to the environmental impact, has fine economic benefits and environmental benefit.

Drawings

Fig. 1 is a schematic diagram of a specific connection of a sea sludge resource utilization system provided by the present invention;

FIG. 2 is a graph showing the effect of adding sludge biochar on sea sludge desalting performance;

FIG. 3 shows the effect of adding sludge biochar on the germination rate of Marina.

Description of the reference numerals

1-1# pump; 2-a hydrocyclone; 3-1# dehydration unit; 4-fresh water spraying device; 5-a buffer pool; 6-sludge biochar storage; 7-a dosing device; 8-hardening and tempering tank; 9-2# pump; 10-2# dehydration unit; 11-1# belt conveyor; 12-forming a granulator; 13-2# belt conveyor; 14-a dryer; 15-3# belt conveyor; 16-a roasting machine; 17-a cooling device; 18-1# fan; 19-2# blower; 20-tail gas purification device.

Detailed Description

As shown in fig. 1, the utility model provides a sea silt resource utilization system includes: a hydrocyclone 2, a No. 1 dewatering device 3, a sludge biochar storage bin 6, a conditioning pool 8, a No. 2 dewatering device 10, a forming granulator 12, a dryer 14, a roasting machine 16 and a cooling device 17; the underflow outlet of the hydrocyclone 2 is communicated with the inlet of the No. 1 dewatering device 3, the top overflow port of the hydrocyclone 2 and the outlet of the sludge biochar storage bin 6 are communicated with the inlet of the conditioning tank 8, the outlet of the conditioning tank 8 is communicated with the inlet of the No. 2 dewatering device 10, the solid phase outlet of the No. 2 dewatering device 10 is communicated with the inlet of the forming granulator 12, the outlet of the forming granulator 12 is communicated with the inlet of the dryer 14, the outlet of the dryer 14 is communicated with the inlet of the roasting machine 16, and the outlet of the roasting machine 16 is communicated with the inlet of the cooling device 17. When the device works, sea sludge slurry is introduced into a hydrocyclone 2 for separation, the underflow of the hydrocyclone 2 is separated to obtain coarse-particle sand, the top of the coarse-particle sand overflows to obtain fine-particle sludge slurry, the coarse-particle sand is introduced into a No. 1 dehydration device 3 for dehydration and then is discharged as building sand, the fine-particle sludge slurry and sludge biochar are introduced into a conditioning tank 8 for mixing, stirring and conditioning, the obtained fine-particle sludge mixed slurry is introduced into a No. 2 dehydration device 10 for dehydration, the obtained dehydration liquid is discharged into the sea, the heavy metal content in the solid phase of the obtained sludge is directly used as greening soil if meeting the national agricultural sludge pollutant control standard GB4284-2018, the heavy metal content in the solid phase of the obtained sludge is introduced into a forming granulator 12 for granulation if exceeding the national agricultural sludge pollutant control standard GB4284-2018, and the green pellets obtained by granulation are introduced into a dryer 14 for drying, the dried product is introduced into a roasting machine 16 for roasting, and the roasted product is introduced into a cooling device 17 for cooling to obtain a ceramsite product.

According to the utility model discloses a preferred embodiment, 1# dewatering device 3's top is provided with fresh water spray set 4 just sea silt utilization system still includes buffer pool 5, fresh water spray set 4 be used for to by the solid phase result that 1# dewatering device 3 generated sprays the washing, 1# dewatering device 3's filtrate export with buffer pool 4's entry intercommunication, water in the buffer pool 4 is as fresh water spray set 4's circulating water. In this case, the salt in the coarse-grained sand can be sufficiently removed, so that the coarse-grained sand is more suitable for being used as a building material, and the cyclic utilization of the spray water is realized.

According to a preferred embodiment of the present invention, the cooling device 17 is directly cooled by air, and the air outlet of the cooling device 17 is communicated with the fuel inlet of the roasting machine 16, so as to pump the air preheated by the cooling device 17 into the roasting machine 16 as the air required by fuel combustion, thereby realizing effective utilization of energy; and/or, the flue gas outlet of the roasting machine 16 is communicated with the energy source inlet of the dryer 14, so that the flue gas generated by the roasting machine 16 is used as the energy source for drying by the dryer 14, thereby realizing the effective utilization of the energy source; and/or the sea sludge resource utilization system further comprises a tail gas purification device 20, and an energy source outlet of the dryer 14 is communicated with an inlet of the tail gas purification device 20 so as to purify the tail gas and then discharge the purified tail gas.

According to the utility model discloses a concrete implementation mode, as shown in fig. 1, the utility model provides a sea silt resource utilization system includes: the device comprises a pump 1# 1, a hydrocyclone 2, a dehydration device (vacuum belt filter) 3# 1, a fresh water spray device 4, a buffer tank 5, a sludge biochar storage bin 6, a quantitative feeding device 7, a conditioning tank 8, a pump 9 # 2, a dehydration device (filter-press dehydration device) 10 # 1, a belt conveyor 11 # 1, a forming granulator 12, a belt conveyor 13 # 2, a dryer 14, a belt conveyor 15 # 3, a roasting machine 16, a cooling device 17, a fan 18 # 1, a fan 19 # 2 and a tail gas purification device 20. Sea sludge slurry is conveyed into a hydrocyclone 2 through a # 1 pump 1, the underflow outlet of the hydrocyclone 2 is communicated with the inlet of a # 1 dehydration device 3, the overflow port at the top of the hydrocyclone 2 is communicated with the inlet of a conditioning tank 8, and the # 1 dehydration device 3 is provided with a fresh water spraying device 4; the solid-phase product (sea sand) generated by the No. 1 dehydration device 3 is used as a building material after being sprayed and cleaned by a fresh water spraying device 4; a suction filtration liquid phase outlet of the No. 1 dehydration device 3 is communicated with an inlet of a buffer pool 5, and water in the buffer pool 5 is used as circulating water of a fresh water spraying device 4; an outlet of the sludge biochar storage 6 is communicated with an inlet of a 1# quantitative feeding device 7, and an outlet of the 1# quantitative feeding device 7 is communicated with an inlet of a tempering tank 8; the sludge slurry in the conditioning tank 8 is pumped and conveyed to a 2# dehydration device 10 by a 2# pump 9 for dehydration, and in the outlet products (including sludge solid phase and dehydration liquid and discharged out of the dehydration liquid) of the 2# dehydration device 10, if the heavy metal content in the sludge solid phase does not exceed the standard, the sludge slurry can be directly used as greening soil for greening planting; if the content of heavy metals in the sludge solid phase exceeds the standard, the sludge solid phase is conveyed to a forming granulator 12 by a No. 1 belt conveyor 11 for granulation, the outlet of the forming granulator 12 is communicated with the inlet of a No. 2 belt conveyor 13, the outlet of the No. 2 belt conveyor 13 is communicated with the inlet of a dryer 14, the outlet of the dryer 14 is communicated with the inlet of a No. 3 belt conveyor 15, the outlet of the No. 3 belt conveyor 15 is communicated with the inlet of a roasting machine 16, the outlet of the roasting machine 16 is communicated with the inlet of a cooling device 17, and the outlet product of the cooling device 17 is a ceramsite product; the cooling device 17 adopts air for direct cooling, and the preheated air is pumped into the roasting machine 16 by the No. 1 fan 18 to be used as air required by fuel combustion in the roasting machine; flue gas generated by the roasting machine 16 is used as energy for direct drying by the dryer 14, and is pumped into a tail gas purification device 20 by a No. 2 fan 19 for purification and then discharged.

In the utility model discloses, 1

# pump

1 and 2# pump 9 can both be ordinary slush pump. The No. 1 dehydration device 3 can be a vacuum belt filter, and the vacuum degree is preferably more than 0.03 MPa. The # 1 belt conveyor 11, the # 2 belt conveyor 13 and the # 3 belt conveyor 15 can be conventional belt conveyors. The sludge biochar storage 6 can be a common steel bin. The # 1 dosing device 7 may be a screw scale. The buffer tank 5 and the hardening and tempering tank 8 can be both ordinary steel mud tanks or concrete mud tanks provided with stirring devices. The No. 2 dewatering device 10 can be a filter pressing dewatering device, and specifically can be a plate and frame filter press or a high-pressure belt filter press. The forming granulator 12 may be a disk granulator, a drum granulator, a pair-roll former or an extrusion granulator. The dryer 14 may be a track dryer, a tumble dryer, or an oven. The roasting machine 16 may be a rotary kiln or a belt roaster. The cooling device 17 may be a belt cooler or a drum cooler. The # 1 fan 18 may be an ordinary fan. The # 2 fan 19 may be a high temperature fan. The tail gas purification device 20 may be a wet flue gas purification device, a semi-dry flue gas purification device or a dry flue gas purification device.

When adopting the utility model provides a when sea silt resource utilization system handles sea silt, the sea silt resource utilization method that corresponds includes following step:

(1) separating the sea sludge slurry liquid by adopting a hydrocyclone, wherein the hydrocyclone is used for separating bottom flow to obtain coarse-particle sand and overflowing the top to obtain fine-particle sludge slurry;

(2) dehydrating the coarse sand particles to obtain a building material; mixing, stirring and tempering the fine-particle sludge slurry and sludge biochar, and then dehydrating the obtained fine-particle sludge mixed slurry to obtain a sludge solid phase and a dehydration solution;

(3) when the content of heavy metals in the solid phase of the sludge meets the national agricultural sludge pollutant control standard GB4284-2018, directly using the solid phase of the sludge as greening planting soil; and when the content of heavy metals in the sludge solid phase exceeds the national agricultural sludge pollutant control standard GB4284-2018, granulating, drying, sintering and cooling the sludge solid phase in sequence to prepare the ceramsite.

The sea sludge liquid may be a slurry in which various existing sludges are broken up to form a slurry state with a high water content, and may be, for example, a high-concentration sea sludge slurry formed by stirring a sea sludge dredging area by a reamer system in a dredger. Specifically, the sea sludge slurry may have a solid content of 5 to 20 wt%.

In the step (1), after the sea sludge slurry is separated by the hydrocyclone, coarse-grained sand is obtained at the bottom, and fine-grained sludge slurry is obtained by overflowing from the top. The coarse-grained sand can be directly used as a building material after being dehydrated (preferably, the coarse-grained sand is dehydrated by a vacuum belt filter), and can also be further sprayed by fresh water after being dehydrated to be used as the building material. And the fine particle sludge slurry is further subjected to quenching and tempering by using sludge biochar.

In the step (2), the sludge biochar is used for mixing, tempering and dehydrating the fine-particle sludge slurry, so that the physical properties of the sea sludge can be changed, and the permeation rate and the dehydration and desalination effects of the sea sludge are improved. The sludge biochar can be sludge pyrolytic biochar obtained by pyrolyzing sludge of an urban sewage plant. The pyrolysis conditions generally include a pyrolysis temperature of 300-. In the mixing and tempering process, the amount of the sludge biochar is preferably 10-20 wt% of the weight of the fine particle sludge slurry. In addition, the manner of dewatering the fine-particle sludge mixed slurry may be, for example, mechanical pressure dewatering, and specifically, plate-and-frame filter-press dewatering or high-pressure belt filter-press dewatering. The dehydrated liquid obtained by dehydration can be directly discharged into the sea.

In the step (3), when the content of heavy metals in the sludge solid phase meets the national agricultural sludge pollutant control standard GB4284-2018, directly using the sludge solid phase as greening planting soil; and when the content of heavy metals in the sludge solid phase exceeds the national agricultural sludge pollutant control standard GB4284-2018, granulating, drying, sintering and cooling the sludge solid phase in sequence to prepare the ceramsite. Wherein the granulation conditions are preferably such that the diameter of the green pellets obtained is from 3 to 20 mm. The drying conditions preferably comprise a drying temperature of 105-160 ℃ and a drying time of 2-5 h. The sintering conditions preferably comprise a sintering temperature of 1000-1150 ℃ and a time of 20-60 min. The cooling mode is preferably furnace cooling, and the cooling rate is preferably below 20 ℃/min.

According to a specific embodiment, the sea sludge resource utilization method comprises the following steps:

(1) stirring a sea sludge dredging area through a reamer system in a dredger to form high-concentration sea sludge slurry, pumping the high-concentration sea sludge slurry into a hydrocyclone for separation, and separating at the bottom of the hydrocyclone to obtain coarse-particle sand and overflowing at the top of the hydrocyclone to obtain fine-particle sludge slurry;

(2) dehydrating the coarse-grained sand by using a vacuum belt filter to obtain a building material; introducing the fine-particle sludge slurry into a conditioning tank, adding sludge biochar into the conditioning tank, mixing, stirring, conditioning, and then mechanically filter-pressing and dehydrating the obtained fine-particle sludge mixed slurry to obtain a sludge solid phase and a dehydrating solution; discharging the dehydrated liquid into the sea;

(3) when the content of heavy metals in the solid phase of the sludge meets the national agricultural sludge pollutant control standard GB4284-2018, directly using the solid phase of the sludge as greening planting soil; and when the content of heavy metals in the sludge solid phase exceeds the national agricultural sludge pollutant control standard GB4284-2018, granulating, drying, sintering and cooling the sludge solid phase in sequence to prepare ceramsite, so that the full-process resource utilization of the sea sludge is realized.

The present invention will be described in detail below by way of examples.

Example 1 Effect of sludge biochar addition ratio on sea sludge liquid desalting Performance

Sea sludge is taken from two sea areas and is separated by a hydrocyclone to obtain fine-particle sludge slurry 1 and fine-

particle sludge slurry

2, 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% and 25 wt% of sludge biochar are respectively added into the two kinds of sludge slurry for mixing and tempering, clear water is used as a water source, a leaching desalination experiment is carried out, and the time required by salinity of the fine-particle sludge slurry to be less than 0.1% is inspected. The obtained results are shown in fig. 2, and it can be seen from the results in fig. 2 that the time required for the salinity to be less than 0.1% is reduced and then increased after adding the biochar and the fine-particle sludge slurry in different proportions to mix and leach under the same conditions; when the adding proportion of the sludge biochar is 20%, the obtained desalting time is shortest, the effect is optimal, and compared with the method without adding the sludge biochar, the dehydration desalting efficiency can be improved by 1.82-2.05 times. The result proves that the sludge biochar can form a good drainage channel in the sludge, a micro framework is formed to improve the pressure transmission effect in the sludge, the pores of the sludge are increased, the formation of 'micro drainage channels' in the soil body is promoted, the pore water pressure dissipation of the sludge in the filter pressing process is accelerated, the dehydration efficiency of the sludge is greatly enhanced, the desalting effect is improved, and the method plays an important role in the resource utilization of the sea sludge.

Example 2 Effect of adding sludge biochar to sea sludge on the planting of Maryland grass

Stirring a certain sea sludge dredging area through a reamer system in a dredger to form sea sludge slurry with the solid content of 20 wt%, and then separating the sea sludge slurry liquid by using a hydrocyclone, wherein the hydrocyclone is used for separating at the bottom to obtain coarse-particle sand and overflowing at the top to obtain fine-particle sludge slurry. Respectively adding 0 wt% and 10 wt% of sludge biochar (the sludge biochar is sludge pyrolytic biochar obtained by pyrolyzing sludge of an urban sewage plant at 600 ℃ for 1 hour) into the fine-particle sludge slurry, mixing, stirring, tempering, and performing plate-and-frame filter pressing dehydration on the obtained fine-particle sludge mixed slurry, wherein the heavy metal content in the obtained sludge solid phase meets the national agricultural sludge pollutant control standard GB 4284-2018.

And (3) investigating the influence of the sludge solid phase on the planting of the manila grass, specifically, putting the sludge solid phase serving as planting soil into plastic pots with the upper caliber, the height and the lower caliber of 20cm multiplied by 17cm multiplied by 14cm respectively, loading 3.0kg of the sludge solid phase in each pot, setting 3 times of treatment, and developing a pot experiment. The manila seeds were sown into the planting soil in a uniform sowing manner, 50 seeds were sown per pot, and the influence on the germination rate of manila was measured, and the obtained results are shown in fig. 3. After germination, the germination rate and plant height are recorded every day, and after the whole planting period is 36 days, the biomass of the manila is measured before and after planting, and the obtained results are shown in table 1.

As can be seen from FIG. 3, the sludge solid phase obtained after adding sludge biochar to the fine particle sludge slurry and mixing, tempering and dewatering is used for planting the manila grass to help the manila grass germinate. When sludge biochar (control group) is not added, the number of the germination plants is 39, and the germination rate is 78%; when the addition ratio of the sludge biochar is 10 wt% (test group), the number of the germination plants is 50, the germination rate is 100%, and the germination rate is improved by 22% compared with that of a control group. The results in table 1 show that when 10 wt% of sludge biochar is added, the fresh weight of manila grass is increased by 60%, and the dry weight is increased by 38%, which indicates that the sludge biochar is used as a fine-particle sludge slurry conditioner, and the finally obtained sludge solid phase can be used as greening planting soil, so that the water retention and efficiency improvement purposes are achieved.

TABLE 1 Manila Biomass

Note: in table 1, the total fresh weight, the leaf fresh weight, the root fresh weight, the total dry weight, the leaf dry weight, and the root dry weight all refer to the total amount of 50 manila herbs, and if the manila herbs do not germinate, the leaf fresh weight and the leaf dry weight of the manila herbs are zero, and the root fresh weight and the root dry weight are the fresh weight and the dry weight of the seeds.

Example 3 application of sludge biochar modified sea sludge to preparation of ceramsite material

Stirring a certain sea sludge dredging area through a reamer system in a dredger to form sea sludge slurry with the solid content of 20 wt%, and then separating the sea sludge slurry by using a hydrocyclone which separates at the bottom to obtain coarse-particle sand and overflows at the top to obtain fine-particle sludge slurry. Adding 20 wt% of sludge biochar (the sludge biochar is sludge pyrolytic biochar obtained by pyrolyzing sludge of an urban sewage plant at 600 ℃ for 1 hour) into the fine-particle sludge slurry, mixing, stirring, tempering, and performing plate-and-frame filter pressing and dehydration on the obtained fine-particle sludge mixed slurry, wherein the heavy metal content in the obtained sludge solid phase exceeds the national agricultural sludge pollutant control standard GB 4284-2018. Solid-phase forming and granulating the sludge to obtain raw material granules, wherein the diameter of the raw material is controlled to be 5-8 mm; and then conveying the raw material particles into a drying device with the temperature of 105 ℃ through a conveying device to dry for 3h, conveying the dried particles into a high-temperature presintering device with the temperature of 1075 ℃ through the conveying device to sinter for 30min at high temperature, conveying the particles sintered at high temperature into a cooling device to cool to room temperature, and controlling the cooling speed to be lower than 10 ℃/min to obtain the ceramsite material. The performance of the ceramsite material meets the requirements of the light aggregate and the test method GB/T17431.1-1998 standards, and the heavy metal leaching characteristics of the ceramsite material are detected, and the result shows that the content of each heavy metal in the ceramsite leachate is far lower than the identification standard of hazardous wastes (GB/T5083.3-2007). The results show that when the sludge biochar is used as the sea sludge conditioner, the obtained sludge solid phase can be directly used as a production raw material of ceramsite, other auxiliary materials are not required to be added to adjust the chemical components of the sea sludge, and the treatment cost of the sea sludge is reduced; meanwhile, the obtained ceramsite material has no ecological safety risk of exceeding the heavy metal content.

Although embodiments of the present invention have been shown and described, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the principles and spirit of the present invention.

Claims

1. A sea sludge resource utilization system is characterized by comprising: the device comprises a hydrocyclone, a No. 1 dewatering device, a sludge biochar storage bin, a conditioning tank, a No. 2 dewatering device, a forming granulator, a dryer, a roasting machine and a cooling device; the underflow outlet of the hydrocyclone is communicated with the inlet of the No. 1 dewatering device, the top overflow port of the hydrocyclone and the outlet of the sludge biochar storage bin are communicated with the inlet of the conditioning tank, the outlet of the conditioning tank is communicated with the inlet of the No. 2 dewatering device, the solid phase outlet of the No. 2 dewatering device is communicated with the inlet of the forming granulator, the outlet of the forming granulator is communicated with the inlet of the dryer, the outlet of the dryer is communicated with the inlet of the roasting machine, and the outlet of the roasting machine is communicated with the inlet of the cooling device.

2. The sea sludge resource utilization system as claimed in claim 1, wherein a fresh water spray device is arranged at the top of the # 1 dehydration device, the sea sludge resource utilization system further comprises a buffer pool, the fresh water spray device is used for spraying and cleaning the solid phase product generated by the # 1 dehydration device, a filtrate outlet of the # 1 dehydration device is communicated with an inlet of the buffer pool, and water in the buffer pool is used as circulating water of the fresh water spray device.

3. The sea sludge resource utilization system as claimed in claim 1 or 2, wherein the cooling device is directly cooled by air, and an air outlet of the cooling device is communicated with a fuel inlet of the roasting machine.

4. The sea sludge resource utilization system as claimed in claim 1 or 2, wherein the flue gas outlet of the roasting machine is communicated with the energy inlet of the dryer.

5. The sea sludge resource utilization system as claimed in claim 1 or 2, wherein the # 1 dewatering device is a vacuum belt filter; the vacuum degree of the vacuum belt filter is more than 0.03 MPa; the No. 2 dewatering device is a plate-and-frame filter press or a high-pressure belt filter press.

6. The sea sludge resource utilization system of claim 2, wherein the buffer tank and the conditioning tank are each independently a common steel mud tank or a concrete mud tank equipped with a stirring device.

7. The sea sludge resource utilization system according to claim 1 or 2, wherein the forming granulator is a disc granulator, a roller granulator, a pair roller forming machine or an extrusion granulator; the dryer is a crawler-type dryer, a roller dryer or an oven; the roasting machine is a rotary kiln or a belt type roasting furnace.

8. The sea sludge resource utilization system as claimed in claim 1 or 2, wherein the cooling device is a belt cooler or a drum cooler.

9. The sea sludge resource utilization system as claimed in claim 1 or 2, further comprising a tail gas purification device, wherein the energy outlet of the dryer is communicated with the inlet of the tail gas purification device.

10. The sea sludge resource utilization system of claim 9, wherein the tail gas purification device is a wet flue gas purification device, a semi-dry flue gas purification device or a dry flue gas purification device.