This page contains a Flash digital edition of a book.
Balancing the


Ballast Water Challenge


By Tom Vance & Tim Fileman PML Applications Ltd


Eiocheir sinensis (Mitten Crab) - These crabs are known for burrowing into river banks and dykes causing erosion and siltation. They also prey on native fish and invertebrate species, causing local extinctions. Credit: Shaoweiwei/Dreamstime


Ballast water is carried to help maintain stability and is discharged from ships during on-loading of cargo. The biological organisms that live in ballast water are causing headaches in the world of shipping because of regulations controlling their concentration. There is little doubt that ballast water has the potential to cause widespread environmental and economic damage as a result of the introduction of the invasive species that reside in it. What is less clear is the most effective route to practically reduce the invasion threat while being fair to all sectors of the shipping industry.


One example of marine invasive species is the accidental introduction of the North American Comb Jelly (Mnemiopsis leidyi) to Eastern Europe. This species, native to the Eastern Seaboard of the Americas, was introduced to the Black, Azov and Caspian Seas via ballast water discharges from ships. Comb Jellies are thought to have contributed significantly to the collapse


The North American Comb Jelly (Mnemiopsis leidyi) which was introduced to the Black, Azov and Caspian Seas as a result of ballast water discharges from commercial ships. It feeds excessively on zooplankton causing massive economic and social damage through the collapse of fisheries. Credit: Wollworth/Dreamstime


of the Black and Asov Sea fisheries in the 1990s, with massive economic and social impacts; they now threaten similar impacts in the Caspian Sea. Making ballast water safe is not only an environmental aspiration, but, once ratified, the IMO Ballast Water Convention will require ship owners to comply with legislation. The Convention introduces different standards, D-1 and D-2, in a sequential implementation:


• The D-1 Ballast Water Exchange Standard - requires ships to exchange a minimum of 95% ballast water volume;


• The D-2 Ballast Water Performance Standard - requires that the discharged ballast waters have organism concentrations below specified limits. These are <10 viable organisms of >50 micrometres in minimum dimension per m3, and <10 viable organisms of <50 micrometres in maximum dimension and >10 micrometers in minimum dimension per millilitre. Dicator microbe concentrations shall not exceed:


i. Toxicogenic vibrio cholerae one colony forming unit (CFU) per 100 millilitre or one CFU per gram of zooplankton samples;


ii. Escherichia coli 250 CFU per 100 millilitres; iii. Intestinal Enterococci 100 CFU per 100 millilitres.


Eventually all ships will be required to meet the D-2 Standard.


On board treatment One obvious method to make ballast water safe is to use a purpose designed Ballast Water Treatment System (BWTS). These on-board systems treat ballast water using a variety of mechanisms such as filtration, chlorination, UV, cavitation, hypoxia and hypercapnia to reduce the levels of marine life (zooplankton,


|66| ENVIRONMENT INDUSTRY MAGAZINE

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164