Operation ballast water of commercial vessels in Port of Tanjung Emas Semarang

The commercial vessel uses sea water to stabilty a vessel when the vessel is not loading a cargo. The water stabilized for the vessel is known as ballast water. The activity of loading the ballast water for the ship from origin port and dissposal to the distination port has caused impact on spreading the unidenfied organism the local port. Aim of the study to determine disposal value of water ballast either from a foreign merchant vessel or domestic merchant vessel so that Port of Tanjung Emas Semarang (PTES) is able to determine a policy on ballast administration from merchant vessel include a data of Arrival and Departure Report of the Vessels (ADRV) documents for the last five years (2009-2014). Disposal ballast water of domestic vessel to PTES is average about 37,036 m3 and increased by 76.68% in a year. Yearly ballast water disposed from the foreign commercial vessels has reached 576.045 m3 for the last 5 years. The increasing of ballast water is about 122.19%. Level of vunerability on the PTES waters is due to ballast water dissposal caused mainly from foreign commercial vessels. The PTES administration should provide water reservoir and and water ballast treatment of commercial vessels which has 51,090 m3/per month or 81,744 kl/month.


Introduction
A commercial vessel, its operation uses sea water which is kept in ballast tank to maintain vessel's stability. When the cargo is empty, a commercial vessel will suct sea water from port area and it will dischrage sea water in ballast tank after reaching the next port.
Ballast water system in commercial vessel uses Ballast pump to unload or load sea water in ballast tank. In addition to increase ship's stability, sea water in ballast tank is used to get the desirable draft of a vessel, increase speed, change trim, decrease bending moment, control list during loading and unloading the cargoes and increase the vessel's manouver [1].
Water ballast which is discharged by the commercial vessels to destination port has an effect on aquatic environment, the effect at the east cost of Rhode Island has expanded invasion sea weed, migration of jellyfish, Turritopsis dohrnii at seashores in Atlantik and Passific in Panama, Florida. Origin of far away land, Italia, Mallorca, Spain, Okinawa, Panama Coast, have spreaded VHSV virus in 55 fish species in fish at Great Lake waters [2][3][4].
The impact of ballast water dicharge is also found Asian shrimp Palaemon macrodactylus at east cost of US and New York estuaries in 2001. Moreover a female shrimps which is carry the eggs is found (2001-2002, and 2008) showing the shrimps her doubled [5].
International Maritime Organization (IMO) has legalised a rule of ballast water of commercial vessel via Ballast Water Management Convention in 2004. One of the preliminary requirement is D 1 standard or first standard. It stated that vessel must exchange ballast water in the mid sea ocean range 200 mil before entering distination port or at a depth of at least 200 m in order to minimize spread of the hazard organisms in waters [6,7].
There are three methods of ballast water exchange as follows the sequential method (the process with the emptying of the ballast water and recharged to obtain at least 95% volumetric exchange), the flow-through method (the process of replacing the ballast water so that water out through overflow or other arrangement), the dilution method (the process of replacing the ballast water filled through the top of the ballast tank with the simultaneous discharge from the bottom of the tank) [7].
The purpose of this study is to analyze the volume of the ballast water of commercial vessels disposal coming to PTES waters for a period of five years and to provide data to PTES administrator to formulate the volume of supply and storage of ballast water from commercial vessels at PTES as the cheapest option in the management of ballast water from commercial vessels.

Material and methods
Ballast water capacities are calculated for each commercial vessel witth Dead Weight Ton (DWT) more than 400 Gross Tonnage (GT) arrived at PTES waters according to the result from IMO for general cargo vessel 36,5%, bulk cargo 35%, liquid cargo 35%, container 30%, mixed cargo 33%, and Roll on Roll off (Ro-Ro) 33% from DWT [8][9][10]. Source of incoming and out going commercial vessels from PTES waters used source of Arrival and Departure Report of the Vessels (ADRV) from port harbour administration and harbour otority (KSOP) Tanjung Emas Semarang for the last five years from 2009 to 2014 [11]. PTES is managed by PT. Pelindo III at central Surabaya, and has a management area covering ports of Banjarmasin,Benoa, Samarinda, Cilacap, Padang Bai, Lembar [12] The discharge of ballast water from a commercial vessel is known from the vessel to unload or load the cargo. If the vessel unload all cargoes in a port then to arrange the draft, either the bow or stern, the vessel has to ballasting of sea water at the port to compensate for the vessel even keel event (there is no big difference between the bow and stern draft) . Whereas if the vessel loads to the entire hatch or existing cargo space, the vessel must deballast the seawater (from the port of origin to the loading port) to compensate for the cargoes.

Results and discussion
The domestic commercial vessel berth at PTES in 2009, DWT is about 693,470 MT, maximum DWT accumulation was on October whereas the minimum was on November. It's appropriate to its capacities of ballast tank there at the same month has experienced the maximum and minimum condition. Discharge ballast for each month reached 4,089.75 m³ with the minimum dispossal on February (1,286 m³), maximum on October (8,121 m³).
There have been any increased disposal ballast water as 60.64% in 2009. The arrival commercial vessels at PTES on November are at minimum (70 vessels) which is the smallest vessel is about (533,990 MT) and the smallest capacities are (186,080 MT), because there were more vessel loading the cargoes, there was more ballast water dispossal (6,088 m³) (Figure 1 a. )  In April 2010, foreign's commercaial vessel DWT and ballast tank capacities coming to PTES experienced a maximum condition of 1,130,451 MT and 353,430 MT respectively, minimum in September with DWT vessels of 677,596 MT and ballast tank capacities of 212,693 MT. The vessel that discharges the ballast water experienced a maximum condition in December of 41,590 m3, the minimum month of May of 29,917 m3 and the monthly average of ballast water discharge of 34,776 m3. Foreign vessels coming to PTES in 2010 are decreasing, it can be seen from DWT and its ballast tank capacities are 3.71% and 6.08% respectively. However, for the discharge of ballast water from foreign vessels increased by 37.36%, it was due to an increase in the loading of cargoes for export (Figure  2   The average DWT and ballast tank capacities of foreign vessels coming to PTES amounted to 978,757 MT with maximum and minimum DWT in October and April. There was decrease of foreign vessels arrival these year is indicated by the decrease of average vessels's DWT by 3.9%. In line with this, the ballast water discharged by foreign vessels also decreased 6.68%. Average ballast water disposed of 44,783 m3, with maximum discharge conditions in January and minimum in August (Figure 4   Foreign commercial vessels coming to PTES totaling 676 vessels with a mean dead weight of 1,011,526 MT, with April experiencing maximum conditions and the minimum September of 1,589,247 MT and 813,035 MT respectively. In line with the dead weight of the vessel, the tank capacities of the ballast water also follows where it has experienced maximum and minimum conditions in the same month. Ballast discharges from foreign vessels average 56,165 m3, maximum in April (105,338 m3) and August (34,479 m3). Increased discharge of ballast water from the beginning of the month was small at value 3.34% (Figure 5 b.).
The dead weight of domestic commercialvessels coming to PTES with an average of 934,149 MT, an increase in ship arrival by 20% from the beginning to the end of the month. The domestic's vessels arrival of totaling 143 vessels, the deadweight and ballast water capacities in September became the maximum (1,119,560 MT and 385,250 MT). However, this condition does not apply to ballast water discharges, due to the most loaded vessels, experiencing maximum conditions in February with a value of 4,044 m3, and a minimum in May (990 m3). The discharge of ballast water into PTES waters was a relatively small increase of only 1.33% (Figure 6 a.).  The dead weight of foreign vessels coming to PTES ranges from 10,611,524 MT-15,184,422 MT with an average DWT of 12,257,847 MT/year. There was an increase during 5 years period of 5 years in foreign vessels arrival and dead weight in PTES amounting to 54.59% and 43.09%, respectively. In line with this, the capacities of the ballast water also increased with the same value. The average annual ballast water discharge of the foreign vessels within that period reached 576,045 m3, with the maximum and minimum discharges in 2014 and 2009. There was a significant increase of ballast water discharge by foreign vessels by 122.19%. This shows that foreign vessels coming to PTES are more cargo loading for export (Figure 9.). Effectiveness level of mid ocean ballast water exchange rates shows a decrease in Skeletonema costatum abundance on container vessels entering to Hong Kong port from California waters, a decrease in abundance of diatoms and dinoflagellates on commercial vessels originating from Mexico [13,14].
The strategy undertaken by the European shipping community in response to the Ballast Water Management (BWM) Convention is to enforce this Convention as a temporary solution despite its limited effectiveness, in collaboration with agencies developing BWM Convention in Europe to help harmonize BWM requirements across Europe [15]. The study of the effectiveness of mid ocean ballast water exchange shows the greatest exchange occurs when the source of sea water comes from the port with a low salinity and the exchange will be effective when it occurs in deeper waters than the land, so the ballast water exchange does not discharge all taxa from the port of origin and unsuitable in a regional ballast water setting [16].

Conclusion
DWT of domestic's commercial vessels coming to PTES for 5 years ranges from 8,321,640 to 11,790,736 MT with an increase of 41.69%. The average of ballast water discharge to PTES is 37,036 m3/year, an increase of 76.68%. Arrival of domestic and foreign vessels to PTES during 5 years has increased where for domestic ships 35% while overseas ship 54.6% The weight of foreign commercial vessels coming to PTES are about 10,611,524 MT-15,184,422 MT. The average ballast water discharge of foreign vessels within 5 years reaches 576,045 m3/year. The significant increase of ballast water disposal by foreign vessels are 122.19%.
The vulnerability level of PTES waters due to ballast water disposal is mostly caused by foreign vessels compared to domestic vessels due to the foreign vessels more load cargoes compared to domestic vessels.
The administrator of PTES should provide a reception and ballast water treatment facilities from a commercial vessel with a capacity of 51,090 m3/month or 81,744 kl/month.