---

Scandlines says it is now utilizing a new onshore scrub water treatment system, MarinePaq, for two of its ferries, the M/V Berlin and M/V Copenhagen.

The treatment system, developed by Apateq, cleans scrub water from the ferry's closed-loop exhaust gas scrubber, and is said to produce an effluent that meets the most stringent environmental legislation, whilst also reducing operational costs and yielding flexibility gains for the fleet.

How it works

The ferries' closed-loop scrubber cleans the exhaust gas using a mixture of water and sodium carbonate in powder form. Contaminated water from the scrubber is channelled to an onboard separator for purification. When the solution cannot absorb more waste products, the scrub water is pumped into the MarinePaq shore-based scrub water treatment system, which has been installed in two containers stacked one on top of the other at Gedser harbour in Denmark.

"In a five-step process, the scrub water treatment system cleans the scrub water so effectively that the cleaned water can be discharged into the harbour according to the most stringent environmental legislation, being substantially beneficial for the environment," Scandlines explained.

The five-step process

MarinePaq onshore is based on a five-step treatment system designed to fit into several shipping containers or in a fixed installation, depending on the flow capacity.

1. Pumps drive water from a storage tank to the first treatment step, a chemical-physical pre-treatment. It removes nitrite, sulphite and partially heavy metals.

2. Using Apateq's ultrafiltration system, soot and remaining suspended solids - as well as free and emulsified oil - are removed from the scrubber water. Specially conditioned membranes are operated in a cross-flow mode, removing TSS including soot to a level of below 1 mg/l.

3. Subsequently, a granulated activated carbon filtration further reduces COD from the water by absorbing the contaminants.

4. The post-treatment is done by selective ion-exchangers that remove nitrate and heavy metals to the needed low concentration for the direct discharge limits.

5. Finally, sludge dewatering takes place with a fully automated chamber filter press, including an automatic filter cloth-cleaning process.

Lower disposal costs, 'higher quality of purification'

By operating the MarinePaq on shore, Scandlines aims to save expensive water disposal costs for hauling the scrub water to the nearest industrial wastewater treatment facility. The ferry operator is also not dependent on the availability of external water disposal providers, thereby saving time and gaining flexibility.

When comparing the MarinePaq with other solutions, Scandlines says the MarinePaq onshore treatment system achieves "a much higher quality of purification than any other existing scrub water treatment system, such as the ones offered for onboard applications. Heavy metals, COD, nitrite, sulphites and nitrates are being reduced to much lower levels than any other solution currently implemented".

Hybrid propulsion, lower fuel consumption

Scandlines' two recently launched ferries for the Rostock-Gedser route are driven by a hybrid propulsion system which combines traditional fuel with electric battery power. The propulsion system is designed to optimise consumption by adjusting the engine output.

Together with other optimisation initiatives, Scandlines claims the vessels' fuel consumption has been reduced to almost one-third per crossing per car compared to the former ferries operating the route.