Stolt Tankers, Stolthaven Terminals join forces on onshore washwater treatment

Stolt Tankers and Stolthaven Terminals have joined forces on 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.

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.”

“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,” Daniel Strydom, General Manager, Stolthaven Houston, added.

The project is in line with Stolt Tankers’ pursuit of ways to achieve their own sustainability ambitions and meet commitments under UN Sustainable Development Goal 14, Life Below Water – conserve and sustainably use the oceans, seas, and marine resources.

“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.”

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.

On the flip side, there was a 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 O’Brien. “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.”

“Stolt Innovation was our first vessel and she discharged approximately 1,700 m³ 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,” Strydom recalls.

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 O’Brien. “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.”

As informed, 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.

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 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 Olsson. “When we started this project with Stolt Tankers, we knew that it could be the ideal layby space for ships to discharge wastewater.”

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 O’Brien. “We’re looking to extend the project to Stolthaven New Orleans next and, wherever possible, we will look to use Stolthaven Terminals’ facilities.

“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,” Strydom concluded.