The Effects of Wastewater Treatment Plant Failure on the Gulf of Gdansk (Southern Baltic Sea)

Abstract

In August 2019 and during August/September 2020, the main collection system of the Wastewater Treatment Plant (WWTP) in Warsaw, Poland, malfunctioned. During that system failure, over 4.8 million m3 of untreated wastewater was dropped directly into the Vistula River in just a few days. It is currently considered as one of the largest known failures of WWTP worldwide. In order to assess the environmental impact, water samples were collected from 2 spots at the Vistula river estuary (406 and 415 km from the discharge location, respectively), and 4 spots at the Gulf of Gdansk, situated on the southern shore of the Baltic Sea. The sampling was conducted before the wastewater wave reached the Vistula river’s mouth, followed by daily sampling during 21 days after the malfunction occurred. The study showed the decline in water quality at the Vistula river estuary and the Baltic shore waters as the wave of wastewater reached those points, despite being situated over 400 km downstream from the place of the accident. Those changes included the reduction in the dissolved oxygen content (by 0.69-fold at its peak), the increase in Total Organic Carbon (TOC) (by 1.28-fold at its peak), nitrate-nitrogen (N-NO3) (by 1.68-fold at its peak), phosphorous (P) (by 2.41-fold at its peak), conductivity (by 16.8-fold at its peak), and Chemical Oxygen Demand (COD) (by 1.84-fold). In the samples from the Vistula river, the decline in water quality was seen as incidental and lasted 2–3 days. Subsequently, the levels of physical and chemical parameters returned to the levels from before the accident. However, the changes in the Gulf of Gdańsk lasted significantly longer, especially on the West side of the Vistula river, where, even after 21 days from the initial accident, some parameters remained altered.

Global-scale parameters for ecological models

“…Sea-bottom dissolved oxygen was inverse-correlated with sea-surface temperature at the global scale, and in the Baltic, Black Sea, North Sea, and Western Mediterranean, as inferable also by other studies; 63 , 64 , 78 , 83 – 85 …”

“…These observations agree with those of other studies; 14 , 74 – 77 Sea-bottom salinity was generally positively correlated with sea-surface salinity in most seas except for the Black Sea, due to peculiar deep and shallow thermohaline dynamics 78 . It was also positively correlated with sea-bottom temperature in the Adriatic, Aegean, Bay of Biscay, and Levantine, as can also be inferred by other studies 79 – 82 ; Sea-bottom dissolved oxygen was inverse-correlated with sea-surface temperature at the global scale, and in the Baltic, Black Sea, North Sea, and Western Mediterranean, as inferable also by other studies; 63 , 64 , 78 , 83 – 85 Sea-ice concentration had no significant correlation with the other parameters. …”

Risk Assessment of Domestic Wastewater Treatment System Based on Constructed Wetlands

“…Examples of these situations include accidents at the Warsaw city wastewater treatment plant in 2019 and 2020, when approximately 3.6 and 4.8 million cubic meters of raw wastewater were, respectively, discharged into the Vistula River. Another instance occurred at the wastewater treatment plant in the city of Fort Lauderdale, Florida, USA, where close to 1 million cubic meters were spilled [4,5]. Domestic wastewater treatment systems based on constructed wetlands (CW) are considered a technological process that simulate natural systems, exhibiting high efficiency in the degradation of organic matter and industrial pollutants.…”