Shipowners are increasingly concerned about meeting the new sewage treatment guidelines for passenger ships in the Baltic Sea and are updating their wastewater treatment systems accordingly
As IMO’s new directive for the Baltic Sea Special Area approaches, wastewater treatment manufacturers and cruise ship operators are working hard to meet its requirements. IMO MEPC.227(64) including section 4.2 is set to come into force for newbuild passenger ships at the start of June 2019 and for the existing fleet on 1 June 2021. It states that nitrogen must be removed before wastewater is discharged into the Baltic Sea Special Area. The options for meeting this regulation include holding the sewage and discharging at port, or deploying an advanced wastewater treatment system that removes nitrogen.
Scanship has noted an increasing demand for its advanced wastewater system that removes nitrogen, according to chief technical officer Henning Mohn: “Shipowners are more and more concerned about the new Baltic Sea regulations and they want to retrofit to make sure they are ready for these new regulations.”
While the regulation only covers the Baltic Sea, Mr Mohn pointed out that passenger ship operators are looking at installing such systems in ships that do not currently trade in this area, to have the flexibility to redeploy the fleet in the future. “They want to future-proof their vessels,” he noted.
Henning Mohn (Scanship): Passenger ship operators want to ‘future-proof’ their vessels
The Scanship Advanced Wastewater Purification system (AWP) is designed according to IMO Marpol MEPC 227(64) for nutrient removal, in addition to the removal of organic matter, suspended solids, residual chlorine and faecal coliforms.
Scanship is currently retrofitting a Scanship AWP system on Norwegian Cruise Line Holdings (NCL) vessel Insignia (operated under its Oceania Cruises brand). The installation follows an AWP retrofit with nitrogen removal on Insignia’s sister ship Sirena in 2016.
The Insignia retrofit is the13th contract for a wastewater retrofit that Scanship has performed for NCL and the second for Oceania Cruises. Scanship AWP with nutrient removal is also installed on NCL’s Breakaway Plus-class and will be fitted on its new Leonardo-class, to be built at Fincantieri.
In all, Scanship has fitted its AWP on 60 new cruise ships and conducted 26 retrofits. Mr Mohn said that MEPC.227(64) has contributed to Scanship AWP’s presence on half the cruise ships delivered since 2014.
MEPC 227 (64) is also a key area of focus for Wärtsilä Water Systems (WWS).
WWS has type-approved membrane bio reactor systems operating to MEPC 227(64) requirements. “These systems produce a reliable effluent quality without significant operator intervention or increased operating costs over and above the small amount of chemical required to remove phosphorus,” said WWS process and proposals manager Peter Woollard.
He pointed out that all of the principle suppliers in the market have type-approval to MEPC 227(64): “Over the next few years it will become apparent which of these solutions can deliver a consistent effluent quality at the lowest operating cost. In this regard, membrane bio reactors offer a solution that requires less energy when removing nitrate from the wastewater and the option to switch off the chemicals when phosphorus removal is not required.”
WWS is currently delivering full waste management systems for Saga Cruises and Genting Crystal Cruises. In addition to these projects WWS has recently been awarded the contract to deliver a waste management system for a 7,000-person cruise vessel. This new project will comprise an integrated waste management system, with the liquid waste stream being treated to MEPC 227(64).
“When discharged into the marine environment, grey water can flood the surrounding environment with nutrients, overloading the biological make-up of the eco-system”
WWS has two paragraph 4.2-compliant vessels for Seabourn Cruise Line, one in service and one due for commissioning later this year. It has also recently commissioned a vessel for MSC with its membrane bio reactor system and is set to deliver a second before the end of the year.
Mr Woollard said that in each case the wet waste system’s space was a particular challenge. He said: “Here WWS are able to offer an advantage to our customers as the bio reactor volumes required are significantly smaller than would be required for other current market technologies. This is due to the fact that the external membrane bio reactor can utilise a much higher concentration of biomass in the bio reactor, which delivers a like-for-like saving on the bio reactor volume.”
He said that typically WWS would expect its bio reactor to be two-thirds that of a membrane bio reactor system. “With the current expectation that all new ships will be ‘Baltic-ready’ this footprint saving is a big help, as larger bio reactors are required to meet this standard,” Mr Woollard added.
Its membrane bio reactor advanced waste treatment system has introduced new technology on the membranes, which has a significant impact on the flux rates (the rate at which treated effluent passes though the membrane wall).
Mr Woollard explained: “With this new innovation the power required to drive the membranes is now half that required five years ago. This upgrade reduces operating costs, footprint and maintenance costs, as well as allowing complete automation of the membrane bank. The newest membranes clean automatically and have significant inbuilt automated functionality.”
WWS has recently developed its other systems and offerings, widening its portfolio to include dry waste management systems as well as wet waste systems. Mr Woollard said that WWS can now offer a complete waste management system incorporating wet and dry waste collection, dry waste volume reduction, incineration, food waste collection, food waste treatment, drying and wet waste treatment. It can also provide an integrated dry and wet waste management system for all sizes of vessel.
Elsewhere, US-headquartered Headhunter’s TidalWave HMX marine sewage treatment plant has been tested by an independent laboratory and certified by the United States Coast Guard in accordance with the latest IMO effluent performance standards. These systems now comply with MEPC.227(64).
Headhunter’s TidalWave HMX marine sewage treatment plant has been installed on a Silversea Cruises vessel
Headhunter president Mark Mellinger said that during 2017, the most notable delivery for a passenger vessel was its TidalWave TW-HMX 7205, delivered to Silversea Cruises to be installed on Silver Galapagos. Mr Mellinger said the installation was done in Panama during a yard period and the final commissioning was finished in March, when Headhunter’s team met the vessel in Baltra, one of the Galápagos Islands.
Mr Mellinger commented on the benefits of deploying the system: “Our TidalWave HMX is smaller than most competitors’ systems and can be integrated in a way that uses the ship’s holding tank for part of the process. This saves space.”
Meanwhile, ACO Marine has been awarded contracts to supply its advanced wastewater treatment technology as retrofit solutions to river cruise vessels operating on European waterways.
The 232-passenger capacity sister ships Ukraina and Moldavia, undergoing refit work at the Ukrainian Danube Shipping Company’s fleet maintenance base in Izmail, Ukraine, will each be retrofitted with a Maripur NF 250 unit.
In a separate agreement, a Maripur NF 150 unit will also be supplied to Linz Shipyard for retrofit to the 150-passenger capacity river cruise vessel Carissima.
“If we follow the spirit of Marpol Annex IV, then grey water must be added; it has a far greater environmental and human impact than any other wastewater stream”
Due to space limitations aboard all these vessels, ACO Marine will use the ships’ existing holding tanks as a bio reactor in the first stage of the treatment process.
ACO Marine managing director Mark Beavis said: “Usually the main biochemical purification process occurs in the first-stage activation chamber of the Maripur NF unit, but by converting the vessels’ existing tanks – provided they are of sufficient size – we can create an environment in which bacteria can thrive.”
He said ACO Marine needed to install blowers and additional pumps, but it was still a much simpler process.
Mr Beavis added: “This is a much more cost-effective approach to wastewater treatment where space is a limitation. Using existing tanks in this way can reduce the system footprint by more than two thirds, depending on the dimensions of tank, and reduce capital expenditure. However, additional tank venting would be required for safety reasons.”
Barrier Reef spill highlights need for grey water rules
Reports that a cruise vessel discharged several thousand litres of food waste and grey water into the Great Barrier Reef should send a clear message to IMO that Marpol Annex IV needs urgent revision, according to ACO Marine managing director Mark Beavis.
While the alleged incident is still under investigation by the Australian Maritime Safety Authority, ACO Marine said that the pulped slurry could have been transferred from a food waste holding tank to the ship’s grey water holding tank, from where it was unintentionally discharged overboard into the protected marine park. The incident occurred on 26 August 2018.
“There are local rules regulating the discharge of ships’ grey water, but there is still no internationally-enforced requirement to prevent the damage that this waste stream can have on the marine environment and, ultimately, human health. Grey water is such an under-reported threat; much more so than oily water, black water and sewage,” said Mr Beavis.
When discharged into the marine environment, the oils, fats, detergents, chemicals, greases, galley waste and micro- and nano-plastics that make up the grey water stream can flood the surrounding environment with nutrients, an ACO Marine statement explained. “It overloads the biological make-up of the eco-system, is being consumed by marine life and is entering the food chain,” said Mr Beavis.
In October, researchers at the Medical University of Vienna and the Environment Agency Austria published the results of a study into the amount of microplastic found in human stools.
The study, the first of its kind, analysed stool samples from eight participants around the world. None of the participants identified themselves as vegetarian and six ate fish. The samples contained up to nine different plastics of between 50 and 500 micrometres in size. On average, researchers found 20 microplastic particles per 10g of stool.
“If we follow the spirit of Marpol Annex IV, then grey water must be added because it has a far greater environmental and human impact than any other wastewater stream,” said Mr Beavis.