Risk assessment in municipal wastewater treatment plant

Abstract

Each technical facility is exposed to a risk that will hinder or prevent its proper functioning. Risk assessment is a component of the risk management process in municipal wastewater treatment plants, the purpose of which is to reduce the occurrence of events as well as their resulting effects, which adversely affect the operation of the treatment plant. The authors, having based their work on the identification of risk-related phenomena, estimated the value of risk and determined its acceptability. The result of the work was to obtain a risk matrix – in other words, a risk map with a designated hierarchy. This could then be used as a basis to determine the level of risk that an event triggered. This allows for faster response to risky situations and an optimal selection of remedies.

Analysis of Risk Assessment in a Municipal Wastewater Treatment Plant Located in Upper Silesia

“…In the case of SWT-2, there were also two events classified as tolerated risk-the dump of greasy wastewater in the grit chamber and auxiliary device failure of the clarifier [27,28]. The dumping of greasy wastewater into the grit chamber was also reported in SWT-1, but in this case, it was classified as an acceptable risk because it occurred more frequently (once in SWT-1 but eight times in SWT-2 [27,28]). The auxiliary device failure of the clarifier did not occur in SWT-1.…”

“…We conducted a similar study for another sewage treatment plant [27] (SWT-2). In comparison with the treatment plant presented in this paper (SWT-1), there were bar screens instead of sifters, and SWT-2 carried out a chemical dephosphatation process that does not occur at SWT-1.…”

“…In comparison with the treatment plant presented in this paper (SWT-1), there were bar screens instead of sifters, and SWT-2 carried out a chemical dephosphatation process that does not occur at SWT-1. No events for sifters were classified as a tolerated risk for bar screens; there were two such events that occurred 14 times (large fat and meat dump that occurred once and clogging of bars that occurred 13 times [27,28]). In both cases, one event in the activated sludge chamber was classified as a tolerated risk.…”

“…In SWT-1, it was the emergence of filamentous bacteria that occurred frequently (41 times) with a small number of losses (2). While in SWT-2, it was a problem with the agitators and aeration rotors that occurred once but with a very high number of losses (4) [27]. Thus, events with very different frequencies and different numbers of losses may have a similar level of risk.…”

“…For the process of chemical dephosphatation in SWT-2, one event occurred 14 times: sludge floated on the surface of the dephosphatation chamber [27,28]. This did not happen in SWT-1 because there was no dephosphatation chamber in the technological line.…”