Protecting the Rhine

An idyllic view of the Nibelungen Bridge in Worms with its historic tower. The bridge links the city in Rhineland-Palatinate with Hesse. However, few tourists realize that the bridge is on-call around the clock as an environmental detective.

Four automatic sample collectors on the bridge pillars in the Rhine and on the banks collect river water and transfer it through the measurement facilities in the operating building. The sample collectors at Rhine kilometer marker 443.3 have been in operation since 1995 and continuously provide measurement data. The State Environmental Office of Rhineland-Palatinate operates the Rheingütestation (Rhine quality measurement station) at Worms on behalf of the neighboring federal states of Hesse and Baden-Württemberg, too. “We are able to see exactly what is going on in the Rhine,” explained Steffen Schwab, head of the Rheingütestation. The inspectors not only see what substances are in the water: “At the monitoring station, we are able to see exactly which nearby upstream sector of the river is affected, and we also have the support of the river police and the law enforcement agencies,” said Schwab, who is an environmental engineer by trade. The Rheingütestation is the only river measurement station in Germany which is equipped with around-the-clock alert capabilities to notify of water contaminations. The Rhine water is tested biologically, physically and chemically across its entire width, meaning the measurement station at Worms has a watchful eye on the waste water treatment plants and shipping traffic.

Based on the experiences made after the Sandoz catastrophe in 1986, the Rheingütestation was intentionally placed downstream from large plants. With its waste water treatment plant and the cooling water inlets, BASF provides the highest amount of inflow on the western bank of the Rhine.

And BASF also continuously monitors its inflow into the Rhine. Great efforts are made to continuously and automatically inspect both cooling water and waste water for hazardous materials, ensuring that the water quality complies with the inflow regulations of the environmental offices before it is pumped into the Rhine. This process of continuous self-monitoring is the only reason BASF is allowed to pump water into the river.

Adhering to the regulations is mandatory for BASF, which is why the authorities regularly take random samples to monitor compliance. Between 10 and 12 times a year, officials from the Ministry for Environment, Energy, Nutrition and Forestry from the state of Rhineland-Palatinate in Mainz visit the site premises of BASF in Ludwigshafen unannounced and take samples. Michael Alter (ESE/MW), head of water monitoring at BASF: “The density and intensity of the monitoring by the authorities and the requirements for self-monitoring are tightly controlled.”

Each day, a large number of products is manufactured at the Ludwigshafen site. And whether it is used for cooling, flushing or as a raw material, water always plays a part in the process. If something appears in the water that does not belong there, Disruption Management is informed and the team sets out to get to the bottom of the matter. 

Every day, approximately 5 million cubic meters of water from the Rhine flow through the cooling water pipes. As a comparison: An Olympic swimming pool “only” contains 2,500 m³. This cooling water is not polluted and is piped back into the river. Over 30 measuring stations across the site check and ensure that the water is neither too warm, nor polluted.

Waste water is also tested

The waste water which is treated in the BASF waste water treatment plant must also be inspected. It cannot contain any substances in amounts which could damage the waste water treatment plant. The treated water amounts to approximately 300,000 cubic meters per day. The majority of this comes from BASF, with the rest coming from Ludwigshafen and Frankenthal. “We ensure that we find disorders as quickly as possible and solve them,” said Harald Elpel from Disruption Management (ESE/WM). “If we find any deviations, we set out to find the cause.”

Online monitoring in the inlet to the waste water treatment plant provides the first warning, with the samplers on the main waste water canal which runs parallel to the Rhine along the site providing additional data. If potential errors are detected there, the team then immediately takes water samples which are then examined in the laboratory. Once the substance has been specified, it is possible to determine which plants in which sector of the site could be the source of the pollution. These plants then provide samples with their waste water, enabling the team to determine which substance entered the waste water from which plant. “Good cooperation between the plants and Disruption Management is paramount here,” said Elpel. “Depending on the location of the plant, we only have between one and three hours before the waste water reaches the treatment plant.” If it is not immediately clear which plant is responsible, the source has to be honed in on by inspecting each canal to see if pollution is present – painstaking detective work under real time pressure.

After all, if the waste water treatment plant is not properly prepared, excessive concentrations of certain substances could harm the microorganisms in the plant. Elpel explains: “It is therefore all the more important that we know that something is coming as soon as possible. The colleagues at the waste water treatment plant can then divert the affected waste water into storage basins and, once the substance has been identified, either treat the waste water separately, or pipe it into the waste water treatment plant in tolerable doses. This means the waste water treatment plant can continue to run safely and smoothly.”

“The perch bite here a lot,” said Patrick Moser, angler and employee at Disruption Management (ESE/MW). “Here” is at the northern end of the BASF site premises on the Rhine, at the entrance to the harbor. At dusk, the Rhine embankment is a popular meeting spot for anglers as the fish promise a good haul.

But, why is that? Biologist Sascha Pawlowski (FEP/PA) explains: “There are several upstream inlets in the Rhine for our cooling water. The inlet feeds warmer water into the river – and the invertebrates and algae that are eaten by fish thrive in this warmth.” These areas are therefore ideal feeding grounds for fish. They do not mind that it is slightly warmer than in other areas of the river, as long as the supply of oxygen is sufficient.

Scientists call these areas “warm water plumes”: When cooling water is pumped back into the Rhine, it normally has a higher temperature than the river. The stream carries the cooling water along with the current, and if the temperature is measured, the cooling water is recognizable. After thoroughly mixing with the river water, the temperature difference is negated at around Mainz.

Upper temperature limit of 28°C for this river section

In general, the oxygen saturation of the Rhine is excellent over the course of a year – however, if the water temperature increases markedly, the oxygen content drops. Once the water reaches a certain temperature, the “air could get a bit thin” for some fish species. To protect the environment, lawmakers have defined an upper temperature limit of 28°C for this river section, which is based on the requirements of carps. During the summer months, BASF is therefore only allowed to feed cooling water with a maximum temperature of 33°C into the Rhine – as long as the 28°C upper limit has not yet been reached. This is a precautionary measure. Official investigations by the state of Rhineland-Palatinate have shown that there was no fish die-off in 2018 despite the extremely warm and long summer.

Last summer, water temperatures of 28°C were measured at Mainz leading SGD Süd (Struktur- und Genehmigungsdirektion; Structure and Approval Management) to request residents and businesses along the Rhine to reduce their thermal loads. This is a standard procedure at BASF: During summer, a large proportion of the cooling performance is provided by five main recooling plants. These systems compensate for the reduced cooling performance due to excessive water temperatures in the Rhine enabling the thermal load in the Rhine to sink to half the value recorded during winter. Nevertheless, there were still restrictions in production during 2018. The recooling plants were not able to fully compensate for the reduced cooling performance of the warm Rhine water. One large consumer of cooling water at BASF was totally removed from the production line while numerous production plants on site were forced to slightly scale back their production. “To prevent this scenario recurring this year, we are currently implementing various measures to increase the cooling capacities,” said Dr. Thomas Riede. “For example, we have installed more effective fluid distributors in the cooling cells of the main recooling plants, and have implemented measures to improve the air flow. Furthermore, we gain added cooling performance if specific plants pump their waste water into the main recooling plants at much higher temperatures than before: As a result of the waste water reaching the recooling plant with a higher temperature, the plants are able to deprive the waste water of more energy and to work more efficiently. We are working closely with the plants on this,” said Riede.

So, what’s next? Was last year just a one-off? Meteorologist Max Bangert : “2018 really was an extraordinary year, it was extraordinarily dry and extraordinarily hot. Climate researchers forecast that the risk of these weather conditions to recur will increase over the next decades.”