Discharge criteria
排放标准
Any type approved ballast water treatment system shall comply with the discharge criteria regulation D2 and they are;
Capacity discharge for organisms;
- Less than 10 organisms per m3, for organisms> 50 micrometers,
- Less than 10 organisms per ml, for organisms between 10 and 50 microns.
Capacity of indicator microbes; ( cfu – colony forming unit)
- Toxigenic vibrio cholera: 1 cfu per 100 ml
- Escherichia coli: 250 cfu per 100 ml
- Intestinal enterococci: 100 cfu per 100 ml
任何经过批准的 ballast water treatment system 都必须符合排放标准规定 D2，它们是：
生物容量排放要求：
对于大于 50 微米的生物，每立方米不得超过 10 个生物；
对于介于 10 和 50 微米之间的生物，每毫升不得超过 10 个生物。
指示微生物容量要求（cfu - 菌落形成单位）：
霍乱弧菌毒素原性菌：每 100 毫升不得超过 1 个 cfu；
大肠杆菌：每 100 毫升不得超过 250 个 cfu；
肠道肠球菌：每 100 毫升不得超过 100 个 cfu。
General structure of a Ballast Water Treatment (BWT) System
– The ballast water is generally passed through a filter for physical treatment to remove living organisms and dirt of size 50 microns and above. Some systems use cavitation devices as physical treatment.
– Later, the ballast water is sterilized to kill microbes by chemical treatment using chemicals and the treated water is filled in ballast tanks. Methods include emitting ultra-violet rays in water, reducing the oxygen content in water, adding active substances such as ozone and using its sterilizing ability, sterilizing water by using chemicals etc.
– Subsequently, the water is discharged overboard, but for a system in which re-treatment or neutralization is necessary, the water is discharged overboard after such treatment has been performed.
- Ballast water 通常通过过滤器进行物理处理，以去除大于 50 微米的生物和污垢。一些系统使用空化设备进行物理处理。
- 然后，通过化学处理将 ballast water 进行消毒*菌，以*死微生物，然后将处理后的水填充到 ballast tanks 中。方法包括在水中发射紫外线、降低水中的氧含量、添加致活性物质如臭氧并利用其消毒能力、使用化学物质进行消毒等。
- 随后，水被排放到海上，但对于需要重新处理或中和的系统，水在进行此类处理后排放到海上。
Different types of ballast water treatment system
There are 4 different types of ballast water treatment system commonly used. They are;
- UV treatment method
- Gas Treatment method
- Electrolysis method
- Magnetic Separation method.
目前常用的 ballast water treatment system 有 4 种不同类型，它们是：
1.紫外线 (UV) 处理法
2.气体处理法
3.电解法
4.磁分离法
a) UV Treatment method
- 图中展示了 UV 处理法的概览。在第一阶段过滤器中，大型水生生物会随着污垢一起被去除。随后，钛白粉上会释放出光，在光的作用下产生的自由基能够灭菌水生生物和其他真菌。
- 未成对电子的原子或分子称为自由基。通过辐射特定波长的光，钛白粉能够产生活性氧和羟基自由基（OH 自由基），从而具有强大的消毒能力。
- 另外，一些系统使用紫外线进行消毒灭菌。由于此处理系统不使用化学药品，微生物、真菌等可能会在 ballast tank 中再生长。因此，在排放前需要再次通过 BWT 系统对 ballast water 进行处理。
b) Gas Treatment method
– Figure shows an overview of the gas treatment method. When filling ballast water, Inert gas is blown into the ballast water using a Venturi tube, the oxygen concentration of water is reduced, and ballast water is sterilized.
– The oxygen concentration of inert gas is lower than 0.1%, and this is lower than inert gas used for oil tankers (lower than 5%). In addition, some system uses ozone which has strong disinfection. These treatment methods may need neutralization process or water quality adjustment during discharge of ballast water.
- 图中展示了气体处理法的概览。在填充 ballast water 时，使用 Venturi 管向 ballast water 中吹入惰性气体，降低水中的氧浓度并对 ballast water 进行消毒。
- 惰性气体的氧浓度低于 0.1%，低于用于油轮的惰性气体的氧浓度（低于 5%）。此外，一些系统使用具有强大消毒能力的臭氧。这些处理方法在排放 ballast water 时可能需要中和过程或水质调整。
c) Electrolysis method
Figure shows an overview of the electrolysis treatment method with filtration & cavitation. The uptake ballast water is passed through filters and large aquatic organisms and dirt more than 50 microns are removed. – Cavitation damages the cell membranes of organisms, and nitrogen gas purified onboard and hydroxyl ions generated by electrolysis are added to sterilize and to kill aquatic organisms and fungi. – There are no active substances that are brought into the ship from outside the ship.
- 图中展示了带有过滤和空化的电解处理法的概览。吸取的 ballast water 通过过滤器，去除大于 50 微米的大型水生生物和污垢。- 空化会损坏生物的细胞膜，电解产生的氮气和氢氧根离子会被添加到 ballast water 中进行消毒灭菌。- 没有从船外带入船舶的活性物质。
d) Magnetic Separation method.
– Figure shows an overview of the magnetic separation treatment method. This is a treatment system for aquatic organisms, micro-organisms, and microbes in which magnetic powder is fed to the ballast water during its filling, water is agitated and magnetic separation performed.
– No chemicals for sterilization are used. The aqueous ingredients in ballast water are also unchanged, and re-treatment of discharged water, neutralization, etc., are not necessary.
- 图中展示了磁分离处理法的概览。这是一种用于水生生物、微生物和微生物的处理系统，在 ballast water 填充过程中向其中添加磁性粉末，水被搅动并进行磁分离。
- 该系统不使用消毒灭菌的化学药品。ballast water 中的水分成分也不会改变，因此不需要对排放的水进行重新处理、中和等操作。
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