The JONGEN team

is available for all your questions and consultancy about our services.



Julia Dettmer - General management

Since 2012 active in the organisation as a member of the Dettmer family. After the completion of her Master in Barcelona, with main focus on International Business, Miss Dettmer continuous her career in the fields of business consulting, purchasing and fund management.

Miss Dettmer is since 2012 responsible for the fields marketing, PR & communication as well as the property management for Dettmer Group.

In 2016 she took on the leadership of the subsidiary Jongen together with Niels Mohrenz.

Telephone: 040-369 17 56 - 19


Niels Mohrenz - General management

The trained insurance purchaser is since 2000 active in the port business (port economy). For fourteen years he was the CEO of a Hamburg waste disposal company for ship waste, which he developed to become the market leader in 2007.

Following he held a responsible position in the firm REMONDIS, which is working in the oil recycling business. After which he worked together with the Dutch family business JONGEN B.V., to establish Jongen GmbH in Hamburg. Jongen GmbH is since 2016 separated from its’ Dutch mother and is now member of the Dettmer Group KG which has its’ headquarters in Bremen.

“I am excited to be back in a medium-sized company with short decision-making processes and I look forward to implement the expansion strategies in Hamburg’s market. The cooperation with Dettmer Group will support us hereby while we serve the same customer base, therefore we can offer treatment and disposal of ships in the industrial companies from one source.”


Telephone: 040-369 17 56 - 17

Michael Giannandrea – Authorized representative

Michael knows the disposal business and the port of Hamburg like the back of his hand, since he already has nearly ten years of experience with two other ship disposal businesses from Hamburg. With his know-how in disposition and verification, as well as his practical experience as an inspector for disposal and cleaning, he fits the motivated team of Jongen perfectly. Since 01st of september 2021 Michael signed as authorized representative for the company.

Telephone: 040-369 17 56 - 16


Roy Grigutsch - Operational Manager

Roy completed his education as a plumber and fitter.

Already in 2010 he gained experiences of the daily activities of local waste disposal companies. He mainly was in charge of the disposition as well as for the waste verification management.

In 2016 Roy started successfully at Jongen and organizes on his own authority the marpol disposal onshore. Furthermore, he is the first contact for you when it comes to disposition, oil spill fighting and waste record.  .

Telephone: 040 369 17 56 - 15

Marco Hiebenga – Operational Manager

Marco has been involved in the shipping and harbour industry from the start of his working life. After completing his apprenticeship as a shipping clerk, he spent several years widening his experience in a shipping company.

From 2002 Marco was employed in several positions for a tugboat operator in the port of Hamburg, where he was involved in the operative organization on the river Elbe, Weser and Jade, as well as being a competent contact for their customers.
In 2006 Marco completed his Bachelor Degree, Member institute of Chartered Shipbrokers.

Since the start of 2023 Marco, with his long years of experience in port services is now strengthening the Jongen team as operational manager.

Telephone: 040-369 17 56 - 18

Mike Drebold - Operator

Mike Drebold is our specialist for the transport on land and is responsible for the Marpol waste collections over the terminals.

Mike is best placed in Hamburg Harbour due to his knowledge of the harbour and the various waste disposal sites in the area.

He is also responsible for issuing the correct disposal certificates to the ships and ensuring that the waste is correctly disposed, his other duties involve the inspection and maintenance of our road side vehicles ensuring that we are mobile 24/7 all year round.