Research on the calculation model of production and discharge of the water pollutants from transport ships based on AIS data

Ship transportation is an important channel of logistics transportation in China, which has the advantages of low freight rate and large cargo capacity. The water pollutants from transport ships during navigation seriously pollute the water environment. The traditional methods for measuring the production and discharge of the water pollutants from transport ships is costly, and the conclusions are insufficient in real-time, completeness and accuracy, which cannot meet the daily monitoring and supervision needs of the management department. The types, pollution indicators and hazards of the ship pollutants were expounded, and a calculation model of production and discharge of the water pollutants from transport ships based on AIS data was developed. The model included the calculation process and calculation method. The methods for AIS data acquisition, cleaning, thinning and regional screening were proposed. The definitions of the total number of active transport ships and the total activity degree of transport ships was put forward, and the statistical methods for them were put forward at the same time. The calculation formula for production of the domestic sewage, the calculation formula for production of the oily sewage in machinery spaces, the calculation formula for production of the ship garbage, and the calculation models of production and discharge of the pollution indicators were put forward. The definitions and calculation methods of production intensity and pollution intensity of the water pollutants from transport ships and the pollution indicators in inland areas and coastal areas were put forward, respectively. A case study on the calculation of production and discharge of the water pollutants from transport ships on the Changjiang main line was carried out. The daily AIS data of the transport ships from the source to the estuary of the Changjiang from April to November 2017 was obtained, and the parameter values were set according to the measured values and the regional emission limits. Firstly, the total number of active transport ships and the total activity degree of transport ships on the Changjiang main line in 2017 were calculated. Next, the production volumes and intensities of the black water and the gray water in the domestic sewage, the oily sewage in the machinery spaces, the ship garbage were calculated. Finally, the production volumes, production intensities, discharge volumes and pollution intensities of BOD5, CODCr, SS, TN, NH3-N, TP in the black water, BOD5 and SS in the grey water, and petroleum in the oily sewage in machinery spaces were calculated. The calculation model can effectively reduce the difficulty of calculation and work cost, improve the timeliness, completeness, accuracy and credibility of conclusions, and provide technical support for ship pollutant discharge reduction, ship supervision, and policy formulation.