Rederi AB Gotland Looks to the Future

Nutrient removal in membrane bioreactor wastewater treatment systems is the future. Rederi AB Gotland acts now for both savings and the sake of our seas.

Rederi AB Gotland, Sweden’s oldest passenger shipping company, has chosen Evac products to equip its new LNG-fueled passenger and cargo vessels which will ply Baltic Sea routes. Each vessel will carry approximately 1,700 passengers and crew.

And since the Baltic Sea is classified as a Special Area (SA), the new vessels will also carry the most state of the art nutrient removal system.

Nutrient removal: not just a mechanical device

Each of Rederi AB Gotland’s new vessels is equipped with two membrane bioreactors (MBRs), solids screening, 233 vacuum toilets, two buffering tanks, two macerating food waste feeding stations, and one bone shredder.

Each MBR unit is also equipped with a nutrient removal system. Evac Product Manager Mats Riska says that in the past wastewater treatment was viewed as “one more piece of mechanical equipment on board.” But due to compliance requirements for wastewater treatment, all that has changed.

In SAs like the Baltic Sea, ships will soon be required to remove nutrients like nitrogen and phosphorous before returning water to the sea.

“Nutrient removal is a complicated biological and chemical process,” says Riska. “Thanks to Evac’s systems this process can be fully automated so that only a basic process understanding is required from our customers.”

Since not all vessels are destined for SA waters, and because not all ship owners demand it, nutrient removal is not standard on Evac MBR systems. But because compliance regulations will require it in the future, all Evac MBR systems are built to allow an easy upgrade to nutrient removal.

“Our standard MBR is easy to retrofit to meet compliance requirements, with nutrient removal supplied as a one skid installation,” says Riska. “Our product array is very much poised for the future.”

Factoring in future compliance costs, an Evac MBR with upgrade capability makes Evac MBR systems the most competitively priced on the market. “It’s much more cost effective to upgrade than to do a full retrofit,” says Riska.

Touch screen

Another feature found on the Rederi AB Gotland vessels’ MBR units is a touchscreen control panel.

“We gave a total facelift to our MBRs at the beginning of 2015,” says Riska. “We went from mechanical switches to a touchscreen with a great user interface. Rederi AB Gotland will be using the first ones we’ve shipped.”

The touchscreen system offers data logging for all parameters. The user can check process values, and make log data available to Evac for easy service.

Made in China

Another tradition-breaker in the Rederi AB Gotland order is the fact that the two vessels are being built in China. Guangzhou Shipyard International (GSI), the largest, most modern shipbuilding company in Southern China, was awarded the job.

GSI is China’s leader in handysize oil/chemical tankers (up to 50,000 tonnes deadweight), but it is also a company known for undertaking the manufacture of special vessels like the pair for Rederi AB Gotland.

Huang Sheng Ming, the piping engineer responsible for the design management work on the two vessels, is charged with signing technical agreements with systems makers like Evac. Nutrient removal is an area of growing concern to Huang.

“Nutrient removal is a requirement for the near future,” says Huang. “MBR and nutrient removal is our first contact, and with this trend we’re still in the learning stage. But by working with Evac, we are slowly getting to know the rules and the importance of MBR.”


RoPax ferry of Rederi AB Gotland
RoPax ferry of Rederi AB Gotland

Evac in short

Evac is the world’s leading provider of integrated waste-, wastewater-, and water management systems for the marine, offshore, and building industries. The company has executed over 20,000 marine and 2,000 building projects worldwide. Evac has employees in Finland, Germany, France, China, Korea, the USA, Brazil, Norway, and representatives in more than 40 countries. The company’s turnover was 98 million euros in 2015.