DAY-TO-DAY WATER MANAGEMENT
A dedicated area to put a stop to unauthorised ship careening
Ship careening is the main source of water pollution in marinas and fishing ports. It causes a large number of pollutants to be directly discharged into the sea. Recovering this type of waste is therefore necessary for any activity in the port, due its impact on the environment, tourism and trade.
The solution chosen to put a stop to unauthorised ship careening and prevent the discharge of wastewater into the harbour was to build a careening area, compliant with regulatory standards, that eliminates any pollutants in the vessel washing water before being discharged.
The facility made a marked improvement in the environmental quality of the marina. The fact that the facility operates as a closed circuit results in a very low intake of municipally treated water. In addition, water discharge from careening is controlled.
The various steps involved in the water treatment process are as follows :
- STEP 1 : Screen raking to remove the largest waste.
- STEP 2 : Adding flocculent coagulant-type reagents and stirring removes the charges on the surface of particles and causes them to agglomerate into flocculates, thus increasing their weight and promoting sedimentation.
- STEP 3 : Counter-flow lamellar clarification. The counter-flow principle consists in circulating water beneath the lamellar cells, so that the sludge slides on the plates from top to bottom. This concept help trap both fine suspended solids and free hydrocarbons without disturbing either of the two phases (flotation and sedimentation).
- STEP 4 : Filtration of the water.
- STEP 5 : Storage of the water. At the end of the treatment process, the water is stored in the last compartment of the plant.
- STEP 6 : : The water is recycled to be reused for other careening work. As a result no pollutants are released into the environment.
Settling tanks for rainwater treatment
The Port of Calais welcomes both tourist and freight traffic to and from the UK. The permanent road traffic results in severe levels of pollution, leached by rainwater.
There are four settling tanks within the port area: one in the Ferry freight area (September 2004), one at Terminal Berth 8 (July 2006) and another one in the Eastern Harbour (September 2007).
A new settling tank was installed in November 2010 at the Northern embankment.
These treatment plants are used only for rainwater :
- They use cross-flow lamellar clarification. The cross-flow principle consists in circulating water and sludge perpendicular to each other.
- – This concept uses a compact particle settling tank to trap both fine suspended solids and free hydrocarbons without disturbing either of the two phases (flotation and sedimentation).
Control of pollution incidents
PPollution of piers and quayage : : to mitigate any pollution incidents (oil or fuel spills, etc.) the Port of Calais staff use emergency pumping kits consisting of carpets, pads, tubes, gloves, absorbent powders.
Pollution of the dock area : : it is essentially an hydrocarbon pollution occurring during ship refuelling. The Nord Pas-de-Calais Regional Authority, as the dock area managing authority, uses absorbent tubes, mops and cloths to contain pollution and skim the dock area.
