Estimation of the sludge toxicity at the Samara Wastewater Treatment Facilities

Summary

The results of studying the chemical composition of domestic wastewater sludge picked from a pressure pipeline from sludge beds of the Samara municipal wastewater treatment facilities for the period 2019–2023 are presented. The sludge from the sludge pipe contained excessive concentrations of Hg, Ni, Pb, Cd, and Zn in 2021; however, the listed above concentrations in the sludge from sludge beds met the SanPiN standards. The sludge also contained high levels of aluminum, which is not regulated. However, aluminum has a negative impact on the plant growth and development. In 2021, the sludge supplied through the sludge pipeline exceeded MPCs (based on the upper limits of the values being monitored) by approximately 9.9 times for mercury, approximately 2.1 times for nickel, approximately 5.5 times for lead, and approximately 2.5 times for zinc. The similar average annual copper concentration in 2023 exceeded MACs by approximately 1.02 times. No indicator exceeded MPCs in the sludge picked from sludge beds. Taking into account the obtained interval estimates of the deviations from the averages, the physicochemical composition of the sludge from the sludge beds was comparable to that of the sludge from the pressure sludge pipeline (except the data for 2023).

Key words

sludge , iron , heavy metals , aluminium , sludge beds , chemical properties , sludge toxicity