Tackling maritime emissions encompasses more than just attempting to keep the air clean and the sky blue – we also need to address what hits the water. Water management specialist RWO discusses the pressing issue of toxic wastewater and sewage, looking at what can be done to safeguard fragile marine ecosystems and enhance the industry’s environmental standing.
Emissions to air have, quite rightly, garnered attention from a broad range of stakeholders within industry and society, leading to stringent regulations and ambitious environmental targets. However, Lars Nupnau, Business Development Manager of leading marine water treatment company RWO, argues that waste emissions to water have largely floated by under the business, media and regulatory radars, failing to raise the concern they urgently deserve.
Global, regional and national regulation is necessary to drive wider investments in water treatment technology.
No time to waste
“Smart and efficient water treatment onboard vessels is vital in curbing shipborne discharges of hazardous waste – waste that damages the marine environment in the same way emissions harm the atmosphere,” says Nupnau.
He notes that individual shipping companies are waking up to this reality, particularly in the cruise segment, adopting new technology to safeguard the seas. However, Nupnau adds, more needs to be done on an industry-wide scale – and quickly:
“Global, regional and national regulation is necessary to drive wider investments in water treatment technology. Although the world is slowly moving towards tighter sustainability regulations and standards for water management, effective policing of the oceans has so far been lacking.”
That’s not to say that a regulatory regime is not in place, rather that more needs to be done.
Existing rules are built on the foundations of MARPOL, the International Convention for the Prevention of Pollution from Ships, adopted by the IMO in 1973, covering discharges of substances such as sewage, wastewater and oily water. This was updated with Annex IV, implemented in 2003, prohibiting discharges of sewage into the sea unless the ship has an approved sewage treatment plant in operation, or is discharging sewage that has been broken down and disinfected with an approved system at a set distance from the coast (more than three nautical miles)1.
In addition, in 2011 IMO's Marine Environment Protection Committee (MEPC) moved to protect the Baltic Sea. At this point it was designated a “Special Area” in which all sewage discharges from passenger ships are prohibited unless the vessel has a type-approved treatment plant that removes the nutrients nitrogen and phosphorous.
Disappointingly, for those such as Nupnau with a passion for clean seas, the Baltic Sea is currently the only Special Area named under Annex IV. On a brighter note, he adds, that doesn’t mean the first is set to be the last, particularly given the growing environmental awareness of society at large.
“It is fair to assume that more areas will come under the regulations as public pressure to protect the world’s oceans from pollutants continues to grow.”
Cruise companies are focusing more on their ESG image.
From pressure to profit
Customer-facing cruise companies, Nupnau says, are the first to react to that pressure, with increasingly environmentally conscious passengers creating momentum for change.
“Cruise companies are focusing more on their ESG image and are keen to advertise their low environmental footprint as sustainability becomes an increasingly important commercial factor,” Nupnau explains. “Therefore, these companies are looking to invest in advanced water treatment technology, as it gives them a market advantage that can translate into increased profitability, while also putting them ahead of possible regulatory change.”
This applies not only to sewage treatment, but also areas such as water recycling, bilge water treatment with oily water separation, and ballast water management.
Nupnau, whose company works with everything from solutions for producing drinking or technical water to technology handling wastewater streams, notes that innovation is now accelerating within the segment. This is leading to advances such as game-changing membrane technology capable of removing over 99.9 percent of solids, including microplastics and viruses, to enhance water purity and prevent diseases.
Last year RWO launched a new-generation wastewater treatment system - its CleanSewage Membrane Bioreactor (CS-MBR), a sustainable biological treatment technology designed to minimize a vessel’s environmental impact.
The CS-MBR uses a three-stage treatment process that entails solids being removed from wastewater during mechanical pre-treatment, followed by a high-performance activated sludge process for biological degradation of pollutants, and separation of treated water from the sludge using a submerged membrane. This results in water that is completely free of solids and pure enough to be used for functions such as laundry.
The type-approved system has already been installed on the two cruise ships - the Celebrity Silhouette and Celebrity Reflection – with a further three Celebrity vessels due to be upgraded this year.
Nupnau says all water treatment technology needs to be “future-proofed” so that control software can be easily tweaked to comply with any upcoming, stricter standards.
For example, the area of oily water separation is subject to tighter regulation now, due to strict Port State Control (PSC) regimes, ie, the inspection of foreign ships in national ports. Incidents of oil pollution are often met by heavy penalties, such as multi-million-dollar fines or even imprisonment.
Technology has advanced together with regulatory pressure, new solutions now enabling remote monitoring of oily water separators, as well as sewage treatment plants. This facilitates earlier intervention to mitigate the pollution risk, says Nupnau.
In it to twin it
RWO, in partnership with TUI Cruises and Leibniz University Hannover, is currently participating in the cross-industry Online Modelling, Simulation and Remote Control System for Environmental Technologies on-board (Cruise) Ships research project, known as OSCAR. Funded by the German government, the project focuses on designing a tool that enables ship management companies to simulate the advanced water treatment systems of a cruise ship onshore, utilising data from the vessel to support crew and provide guidance where required.
Nupnau points out that such technology initiatives are driven largely by commercial factors, as there needs to be a financial incentive to invest in measures for higher standards that also incur higher operating costs.
He concludes: “Some countries, for example Norway, are pushing for stronger regulatory enforcement in areas such as sewage management. However, IMO legislation is moving slowly due to the multiple parties involved. Only when there is joint, global regulatory action across the shipping industry will we see the wider application of water management technology to protect our oceans.”