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The environment is a sensitive issue around the world, so we must base our damage to nature on clear data and accurate calculations, leaving aside emotions. This expert study of our company was complicated and delayed by the lack of data on the amount of partially treated wastewater from the company and some environmental variables. To fill in these gaps, we use the computer model used to investigate such cases by evaluating different scenarios.
Understanding the confusion surrounding the case of Grigeo Klaipėda and the complexity of such a complex investigation, I would like to explain what we have managed to identify and what conclusions we have drawn.
Data and modeling
First, when evaluating the impact of the partially treated wastewater from Grigeo Klaipėda in the Curonian Lagoon, we took all the available data and analyzed what determines the state of the water in the Curonian Lagoon. Our analysis used publicly available data, including monitoring results from the Environmental Protection Agency, Klaipėda Water, Klaipėda Seaport Authority, research on the status of the Curonian lagoon by Klaip Klada University, research from the State Service of Food and Veterinary and Grigeo Klaipėda sewage research.
The collected material was systematized and processed, and some of this data was used for computer modeling. This last method, implemented using special software based on the Delft3D model, allowed a detailed analysis and evaluation of the best scenarios (when the company treats 90% of the wastewater) and the worst (when it treats 15% of the wastewater). wastewater).
As the existing problem related to the environmental conditions of the Curonian Lagoon is the eutrophication of its waters, there are three predominant elements of pollution in the company’s industrial wastewater that can affect the Curonian Lagoon: nitrogen, phosphorus and BOD7 ( biological oxygen demand). We focus our research on these three pollutants.
What conclusions
Research data and modeling results revealed that the partially biologically treated sewage discharge from Grigeo Klaipėda had no significant negative impact on nitrogen and phosphorus concentrations in the Curonian lagoon (upper and lower layers) or was minimal. .
The study also revealed that the increased concentrations of total nitrogen and total phosphorus caused by the discharge of wastewater from the company with incomplete biological treatment had only a negligible effect on the trophic condition of the Curonian lagoon, the potential impact of Grigeo Klaipėda sewage was not made.
Finally, even in the worst case and in the summer season (when the most sensitive environmental conditions are present), the release of BOD7 (biological oxygen demand) did not lead to a significant reduction in dissolved oxygen in the Curonian lagoon. . The earlier conclusion of the study is also supported by the modeling results, which confirmed the effect of BOD7 release, modeling that 85%. Grigeo Klaipėda wastewater would be discharged without biological treatment, it would only be produced in the area near the Klaipėda water discharge site.
How can pollution not harm it?
I fully understand that it sounds strange: contamination has occurred, but no damage has been done.
This and other questions can be answered and supported by the science that we have always relied on to conduct research and present research results. It is important to emphasize that all the data collected and used in the study, as well as the monitoring of the water status of the Curonian Lagoon near the location of the wastewater discharge, did not show any significant increase in pollution. Likewise, monitoring data from state institutions shows that the condition of the lagoon did not deteriorate in the 2012-2020 period, when Grigeo Klaipėda was suspected of contaminating the lagoon.
There are several conclusions and explanations: the specific characteristics of the Grigeo Klaipėda wastewater and the pollution carried out accounted for a very small part of the total pollution of the Curonian lagoon and only had an instantaneous impact, so it cannot be assessed as significant .
Let us now analyze these possibilities in some detail.
Wastewater treatment process. During the company’s papermaking process, the suspended effluent materials formed during the recycling of waste paper formed fine fibers. It is similar in its biochemical composition to decaying wood in the forest, and the fiber itself was precipitated and removed during initial treatment in mechanical treatment plants. In the wastewater, BOD7 consisted only of soluble organic matter, most of which is probably recycled waste paper starch. This starch is also used in the food industry.
The biological treatment of wastewater is a biodegradation that also occurs naturally in nature, simply in the treatment plants this biodegradation is accelerated, creating the most favorable conditions here. The objective of biological treatment is to treat organic matter (carbon and hydrogen compounds) using bacteria present in the activated sludge. Therefore, even untreated sewage naturally oxidizes due to the work of bacteria found in natural waters. In this case, nitrogen and phosphorus compounds are one of the main nutrients that all living organisms need and the effects of these substances in aquatic ecosystems depend on their quantity. However, the nitrogen and phosphorus concentrations in the Grigeo Klaipėda wastewater are low and the total discharge does not affect their concentration in the lagoon.
Specific to wastewater. The results of the pollution models confirmed that even in the worst case, the impact of BOD7 emissions (untreated 85% of the company’s wastewater) is limited to the area near the wastewater discharge site . It should also be noted that before entering the lagoon, the wastewater from Grigeo Klaipėda is mixed with the wastewater from Klaipėda Water, which is ten times larger in terms of volume.
Company contamination accounted for a relatively small part of the total contamination. The most important circumstance: the contamination of Grigeo Klaipėda represented a particularly small, that is, negligible part of the total contamination of the lagoon.
We made calculations: in 2019, even in the worst case (only 15% of the wastewater is treated), the percentage of total nitrogen was 0.044%. of the total flux of Nemunas and 0.13 percent. total phosphorous flux. It should also be noted that the pollution in the lagoon comes from the Russian Federation (Kaliningrad region), but its pollution data is not available to us.
Does our conclusion say that Grigeo Klaipeda is innocent?
In this case, we are scientists and we only value the fact that the pollution caused caused damage to the environment. We have prepared the report of our study in accordance with the Directive of the European Parliament and of the Council on environmental damage (Directive 2004/35 / EC).
As data from the regular monitoring of the state of the water status of the Curonian Lagoon at the Klaipėda water outlet (through which the company’s sewage also flowed into the Curonian Lagoon) collected at five points in 2012 -2020, they never showed that the water status exceeded the allowed pollution standards, all the data collected and the calculations performed confirm that no significant negative impact has been caused on the water status of the Curonian lagoon.
The task of our expert assessment was to determine the fact and extent of the damage caused to the water condition of the Curonian lagoon by Grigeo Klaipėda and, in accordance with EU Directive 2004/35 / EC and its Lithuanian implementing legislation, submit proposals. for environmental restoration measures. We have presented these measures to restore the environment, based on our experience and good practices in the EU and other countries.
I understand that people are surprised: by determining the absence or the small size of the damage, it seems that we are reducing the responsibility of the company. However, we are scientists, we rely only on objective data, measurements and calculations – Lithuanian institutions, their experts are familiar with all research material and conclusions. And the issue of legal and moral responsibility is not addressed to the scientific community, but to the responsible state institutions and the company itself.
In total, more than 30 years of experience, he has carried out numerous environmental risk and impact assessments in Europe, North Africa, South America, Central America, Asia and the Middle East for areas and resources affected by discharges of industrial wastewater in aquatic ecosystems. In almost all cases, these were complex and complex studies that required careful and systematic analytical work. In such complex cases, conclusions can only be drawn from a thorough environmental impact assessment. And it is one of the powers of science that encourages me to look at the work I do even more responsibly.
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