Stolt Tankers and Stolthaven Terminals have joined forces to pioneer the removal and sustainable treatment of wastewater from ships docked in Houston.
Stolthaven Houston and New Orleans have been operating onsite biological wastewater treatment plants for more than 20 years, specialising in the handling of hazardous and non-hazardous wastewater from ships, barges, railcars, trucks and ISO containers.
Both plants operate 24/7 and are used by a range of third parties, from large-scale industrial customers and other terminals to a small-scale local coffee company. The treatment process uses bacteria and other microorganisms to naturally degrade organic contaminants in wastewater and produces readily usable water that can be safely released into waterways*.
“It’s a unique set-up, which began as a way to be self-sufficient in terms of how we treat wastewater and rainwater onsite,” explains Henrik Olsson, Regional Commercial Manager, US. “Now, we are two of, if not the first terminals to expand this service to shipping companies.”
Daniel Strydom, General Manager, Stolthaven Houston, adds: "In 2015, we got approval to expand and modernise the plant. The first phase of this project was completed in 2018 and it allowed us to significantly increase our capability to treat third-party waste, so we approached various customers, including Stolt Tankers, to market the extra capacity."
The timing was perfect. Stolt Tankers was looking for ways to achieve their own sustainability ambitions and fulfil their commitment to UN Sustainable Development Goal 14, Life Below Water – conserve and sustainably use the oceans, seas and marine resources. One colleague suggested discharging washwater onshore.
“This idea was initially thought to be too complicated, expensive and, ultimately, unworkable,” explains Paul O’Brien, Deepsea Operations Manager, Stolt Tankers Houston. “But we are passionate about this topic and started thinking about how we could do it and we knew where to start: Stolthaven Houston has a state-of-the-art treatment facility and, better yet, they’re part of the same company.”
A pioneering partnership
In June 2021 the two divisions began a pilot programme to identify and balance the challenges, costs and benefits of treating washwater from ships at the Houston plant.
It is not a legal requirement for shipping companies to do this, with the exception of toxic cargoes, which must be discharged into shore facilities. So, up to this point, Stolt Tankers’ ships, like all others, had docked at the Houston terminal, emptied their tanks and then steamed out of port, down the Houston channel, to clean their tanks and discharge the washwater before returning to reload.
By discharging onshore, Stolt Tankers also saw the potential to save on steaming emissions and cut both the time spent completing the return journey and the navigational risk of negotiating the busy Houston channel.
Stolthaven Terminals and Stolt Tankers are now leading the way in terms of using our facility to discharge and treat washwater onshore. Just as importantly, we have integrated our teams and operations to make a positive impact on the environment.” – Daniel Strydom, General Manager, Stolthaven Houston
On the flip side, there was the very real possibility that demurrage costs and delays to onward journeys could be incurred due to the extra time spent at dock to discharge the washwater.
“Essentially, we were adding a dock to each ship’s time in port, which is counterintuitive to anyone in the shipping or logistics business,” says Paul. “The trick was to figure out how we could manage that without adding any time or costs. We had to think differently to find the savings – or at least the break-even point – for this to be feasible from a business perspective.”
Daniel recalls: “Stolt Innovation was our first vessel and she discharged approximately 1,700m3 of washwater. The initial calculations showed that we could execute the discharge within the vessel operations window and that it made sense financially. Since then, we have received multiple vessels and – through a lot of testing and data analysis with Stolt Tankers – we can see the benefits to both businesses from a financial, operational and environmental perspective.”
Best intentions backed by science
Over the last eighteen months, the Stolt Tankers team, led by Houston Port Operations, and Stolthaven Houston tested different scenarios and developed a calculator to compare the costs of each one. With the help of Stolt-Nielsen's Global Shared Services Centre in Manila, they also built an app to track usage of the treatment facility and a bespoke dashboard to analyse the results.
“Both businesses have been highly committed to this project,” says Paul. “It has all been additional work on something that is not mandatory but done for the sake of doing something good. The great news is we have been able to do it at no additional cost and people have happily invested their time because this benefits the marine environment.”
Over a year of testing, from June 2021 to June 2022, the Houston project reduced the amount of washwater to sea by over 8,000m3 while reducing CO2 emissions by 600 metric tonnes and preventing the burning of over 200 metric tonnes of fuel.
Together with Stolthaven Terminals we have pooled our expertise and innovative thinking to achieve something new in the industry and positive for the environment. We have proven this is a method of opportunity for shipping and terminals." – Paul O’Brien, Deepsea Operations Manager, Stolt Tankers Houston
An important factor in realising the cost and logistical benefits of the project is Stolthaven Houston’s Dock 11, which was commissioned in 2017 but which currently does not have tanks alongside it.
“Eventually, of course, our plan is to expand our storage facilities to this space, but for now, the dock is not in regular use,” explains Henrik. “When we started this project with Stolt Tankers, we knew that it could be the ideal layby space for ships to discharge wastewater.”
Paul agrees: “Houston’s Dock 11 is an advantage because there are timing demands and challenges around using other berths, but the wider benefits of discharging onshore to a layby are not contingent on any one terminal having a spare dock.”
Stolt Tankers is now looking to expand its onshore discharge programme to other ports that have wastewater or water-reclamation facilities. “We are currently rolling out training to our port teams around the world and having conversations with operators in other regions,” says Paul. “We’re looking to extend the project to Stolthaven New Orleans next and, wherever possible, we will look to use Stolthaven Terminals’ facilities.
“From Stolt Tankers’ perspective, this has been one of the best cross-business projects we have worked on. Together with Stolthaven Terminals we have pooled our expertise and innovative thinking to achieve something new in the industry and positive for the environment. We have proven this is a method of opportunity for shipping and terminals.”
Daniel adds: “This has been, and will continue to be, a successful partnership. Stolthaven Terminals and Stolt Tankers are now leading the way in terms of using our facility to discharge and treat washwater onshore. Just as importantly, we have integrated our teams and operations to make a positive impact on the environment.”
*Stolthaven Houston’s wastewater plant is operated and regulated as a Centralized Waste Treatment (CWT) facility as authorised by the Clean Water Act. All wastewater treated at the plant is monitored throughout the handling process to ensure all regulatory and performance requirements are met. Treated water is discharged directly into the Houston Ship Channel and, as such, is stringently regulated by federal, state, and local agencies to ensure the protection of public health and the environment and prevent water pollution.