Pollution from port operations will not only damage the ecological balance of nature but also further increase the risk associated with port operations. Since the environmental challenges in the coal port area of Huanghua Port are especially severe in comparison to other port areas, we mainly focus on the environmental protection ways adopted by the coal port area of Huanghua Port, which is a typical representative of coal-handling ports in China. The measures taken on environmental protection with the adoption of smart technologies are shown in Figure 6
. Driven by the Internet of Things technologies and big data analysis, Huanghua Port put forward the ecological intelligent control system, which has realized the intelligent management of environmental perception, analysis, and prediction as well as environmental governance. We selected the coal dust concentration, the air pollution index, and sewage recovery amount as the key performance indicators of environmental performance and will discuss the environmental protection measures in detail.
3.3.1. Dust Pollution Treatment
Dust pollution is one of the biggest problems facing coal ports. In the operation of car dumpers, the coal is dumped into the funnel at a relatively high speed, generating heavy dust in the semi-closed space and diffusing to the top of the funnel. After materials fall on the belt conveyor running at high speed, massive dust will be produced in the process of coal transportation under the force of airflow and spread all around. To protect the environment and ensure the health of workers, Huanghua Port has taken the following measures to overcome the dust pollution problem.
First, by means of benchmarking management, using the Port of Newcastle, Australia as the target for benchmarking, Huanghua Port analyzed their dust suppression sprinkler systems and developed a series of technologies on dust suppression in 2016. For example, in addition to the widely used dust depressor and dry mist dust removal equipment, Huanghua Port innovatively implements the car dumper automatic sprinkling dust depression system. Starting with the coal unloading, the sprinkling system operates automatically according to the surface moisture of the coal. The sprinkler is installed in the feeder machine at the bottom of the dumper, facilitating the mixture of the water mist and the coal in the process of vibrating the feeder. Additionally, the sprinkler can function normally in winter since the temperature of the water mist is always above zero. This automatic sprinkling dust depression system has been successfully applied to all dumpers in the port, and this system was awarded China’s National patents.
With the adoption of smart technologies, Huanghua Port established the ecological intelligent control system in 2018. Driven by the big data analysis, the platform predicts the optimal sprinkling and dust suppression plan in advance based on the real-time monitoring of air and water quality at each monitoring point. Based on the plan, the control system automatically controls the dust suppression sprinkler equipment and realizes the accurate dust suppression.
Second, the port has built 48 closed coal silos in the third and fourth phases of coal port construction, each of which is 40 m in diameter and 43 m in height. With a total capacity of 1.44 million tons, this group of coal silos is the largest in Asia. As the coal transfer station in the port, these silos have the advantages of small area coverage, high automation level, and being rainproof, windproof, and erosion-proof, which guarantees the quality of coal. They also effectively avoid producing dust in stacking and taking materials, and significantly reduce the dust emission compared with open storage yards. Therefore, the coal is dumped into the funnel by the dumper with dust suppression equipment, then discharged into the coal storage silos through the enclosed conveyer-belt corridor, and finally loaded into the ship’s hold by the ship loader.
Third, a windproof net with a length of 10,176 m and a height of 23 m, as a useful tool to control the diffusion of dust, is placed around the coal silos. Designed with herringbone steel support, the windproof net has a retaining wall in the bottom and a windproof screen on the top, covering all of the storage yards. More than 90% of coal dust in the bulk coal storage yard can be isolated from outside. The wind speed in the coal yard area can be effectively reduced by controlling and improving the airflow fields.
Fourth, in the road outside the windproof net, large road sweepers and sprinklers work regularly as an auxiliary means to prevent dust spillover and secondary dust pollution. The green land and gardens in the surrounding of the windproof net form the unique control system of the Huanghua Port. The greening rate in the coal port area of Huanghua Port has reached 31.3%. Reaching 1.21 million square meters, the greening area not only decreases the wind speed in the yard but also realizes the effective absorption of dust.
In order to realize the reuse of coal dust, Huanghua Port invested in research and development and constructed the intelligent dust treatment tank, which was officially put into operation at the end of 2017. This intelligent facility can convert the coal dust collected by the sweeper and coal slime deposited in drains into coal. It was found that when the ratio of water and coal dust is 7:3, the coal-containing sewage can be pressed into coal for resale. The project is expected to handle about 50 tons of coal dust per day, generating 30 RMB per ton of dust handled. This project successfully produces good ecological benefits by avoiding secondary dust pollution and brings the economic benefit of more than 0.5 million RMB per year. The investment in the intelligent dust treatment tank was about 15 million RMB, which implies that the static capital recovery cycle is 30 years. It is beneficial to sustainable development from both the environmental aspect and the economic aspect in the long run.
To show the effectiveness of the above measures, we selected four observation areas in the coal port area and 17 observation points in the coal port area of Huanghua Port, which are shown as triangles in Figure 7
Before the building of coal silos, the dust concentration was in the range of 10 to 20 mg/m3 in the open storage yard in 2012, according to the manager of Huanghua Port. It may even exceed the national dust emission standard (15 mg/m3 according to JT 464-2001 of China). After the 48 closed coal silos and the windproof net were fully put into use in 2015, the range of dust concentration was decreased to 5 to 10 mg/m3 in 2015 and 2016. With the car dumper automatic sprinkling dust depression system fully put into use in 2017, the dust concentration was in the range of 1 to 4 mg/m3.
Since the ecological smart control system was built at the end of 2017, the automatic dust monitoring system was put into use. Using TSP (Total Suspended Particles) as the dust concentration indicator, in 2018, the average dust concentration near the storage yard significantly fell to 0.48 mg/m3
. In 2019, the dust concentration was further reduced to around 0.20 mg/m3
. It implies that since 2018, the dust emission had been well controlled. The dust concentration at each observation area in March 2020 is shown in Table 4
. Table 4
demonstrates that the dust concentrations after taking measures are far below than the national dust emission standard, reflecting the effectiveness of the adopted measures.
To visually show the relationship between the environmental improvement and the economic performance, we took the average TSP of the storage yard as an example to examine the evolutions of the throughput and revenues and changes of dust concentration, as shown in Figure 8
. Figure 8
implies that the environmental measures that Huanghua Port took can effectively reduce the dust emission despite the throughput increases. The revenue has a great improvement when the dust concentration significantly decreases.
3.3.2. Air Pollution Treatment
In order to reduce emissions of pollutants such as sulfur dioxide and nitrogen oxides, the Huanghua Port adheres to the green development plan and vigorously promotes the construction of the shore power project. Shore power is the connection of a berthed ship to the area electricity grid in order to be able to shut down its own generators. The International Maritime Organization (IMO) reported that the shipping industry emits about 0.94 billion tons of carbon dioxide in 2012, accounting for approximately 2.2% of global carbon dioxide emissions [30
]. Supplying power to ships by shore power instead of diesel generators can effectively reduce the emission of carbon dioxide, sulfur dioxide, and nitrogen oxide, as well as the noise pollution of ships. Huanghua Port took the advantages of shore power technology in the control of air pollutant emissions and noise reduction, which brought considerable environmental benefit.
At the end of 2017, 11 berths for handling coal in the Huanghua Port supplied shore power to all ships there, accounting for 78.57% of the 14 shore power berths in Hebei Province. For example, the average utilization rate of a berth was around 67% (3600 h of using the shore power system/5400 h of berth occupancy) in the year 2018. The coal port area of Huanghua Port has become the port with the largest total power supply capacity in China, striving to decrease the impact of ships’ daily operations on the coastal environment.
To further monitor air quality, Huanghua Port built an automatic monitoring station for air quality in the operation area. Through the monitoring of indicators such as nitrogen dioxide, sulfur dioxide, carbon monoxide, particulate matter (PM10 and PM2.5), the atmospheric conditions of the Huanghua Port can be readily available. For example, compared to the data in the year 2013 before the intelligent renovation, in 2017, the 24 h average daily level of the primary pollutants including sulfur dioxide, nitrogen dioxide, carbon monoxide, PM10, and PM2.5 in the core area decreased from 55 to 10; the ambient air pollution index changed from 100 to 50; and the air pollution index in peripheral areas changed from 150 to 60. Therefore, air pollution can be prevented with accurate analysis and source control.
3.3.3. Sewage Treatment
Another pollution problem in Huanghua Port is the treatment of coal-containing sewage. Since coal in traditional coal ports is piled up in the open air, some coal-containing sewage will be discharged into the sea during heavy rain. Additionally, the untimely drainage of sewage will cause storage yard waterlogging and interrupt the production process. To tackle the problem, Huanghua Port took the following measures.
On the one hand, the port accelerated the construction of the ecological water system consisting of four projects, i.e., the landscape lake, the artificial lake, and the south and north wetlands, and further reconstructed the sewage pipe network. By the control of valves, the interconnection among waterways can be realized to ensure the circulation of water. Even in extreme weather, all sewage can be stored internally. The sewage is transported to the sewage treatment station through pipelines, avoiding discharging the coal-containing sewage directly into the sea. The water reaching the standard after treatment is used for greening and dust suppression, the economic benefits of which are prominent. On the other hand, the port has built eight new ballast water recovery devices to maximize the recycling of ballast water, saving freshwater resources and satisfying the needs of sprinkling and irrigating.
Furthermore, an intelligent water management system was built to automatically deploy the water resources in order to form an intelligent ecological water circulation by effectively collecting, and reusing ballast water, coal-containing sewage, and rainwater. Taking the recovery of ballast water as an example, the system can analyze and predict the amount of ballast water recovery and the recovery time, through collecting information such as berthing schedule and ship drainage time. The system then offers the water transferring plan based on the water demand and the real-time status of each pump station for maximizing water recycling.
This system creates good environmental and economic benefits by saving water to the maximum level. On the one hand, it has greatly improved the quality of the ecosystem, turning the port area into a park, as shown in Figure 9
and Figure 10
. On the other hand, it brings tangible economic benefits as the initial investment of nearly 18 million RMB has been fully recovered in less than 3 years. In 2017, the Port had recovered 0.53 million tons of ballast water and reused 0.37 million tons of sewage, saving nearly 5 million RMB; in 2018, the Port had recovered 0.6 million tons of ballast water and reused 1 million tons of sewage, saving more than 7 million RMB; in 2019, the Port had recovered 0.98 million tons of ballast water and reused 1.64 million tons of sewage, saving about 11.5 million RMB. Taking the sewage as an example, the comparison of the sewage recovery of the same period in the last three years (the year 2017 to the year 2019) is shown in Figure 11
. It visually demonstrates that the intelligent ecological water circulation system can effectively recycle the water resource and reduce the purchasing amount of water.
To conclude, the decreases in the coal dust concentration and the air pollution index and the increase of sewage recovery amount demonstrate that measures adopted in the port can effectively control pollution and promote the ecological environmental quality.