Risk Assessment and Management of Wastewater Collection and Treatment Systems Using FMADM Methods

To secure operation of wastewater collection systems and treatment plants, it is so necessary to detect any probable vulnerability and estimate undesirable events and severity of their effects. In this paper, a model has been developed to evaluate system operation management in order to deal with serious conditions. The risk assessment phase contains three parts including evaluation of probability of threats, severity of their effects–consequences and vulnerability of the system components. These parameters could be measured by fuzzy multi-attribute decision-making techniques by questionnaire and through defining some criteria for threat assessment. In the risk management phase, risk-controlling approaches are developed by professionals based on risk assessment results and prioritizing the threats. Risk assessment and management model has been conducted through two case studies in Tehran, respectively, as a sample of wastewater collecting and the biggest wastewater treatment system in Iran. The results show that “entry of chemical contaminant” and “change in wastewater quality” were taken the highest score for the west Tehran wastewater collection network and “earthquake” in processing units, sludge treatment and gas storages were taken the highest score in the south Tehran wastewater treatment, reduction strategies of which were presented for dealing of each risk.