Comparison of the Cost-effectiveness of Activated Sludge Systems with Natural Wastewater Treatment Systems in Kermanshah Province

To determine the economic feasibility of wastewater treatment plants requires methods to determine their cost/effectiveness ratio. The objective of the present descriptive analytical study was to determine and compare the cost/effectiveness ratios of two types of wastewater treatment systems operating in Kermanshah Province. For this purpose, data and information on the wastewater treatment plants under study were collected from both local water and sewage companies and treatment plant operators. The data were then subjected to statistical analysis using the SPSS software program. All the costs assoiated with the erection and operation of the treatment processes were analyzed and plant efficiencies were determined to work out the cost/effectiveness index for each plant as a basis for comparisons. Average values of overall efficiency determined from the mean values of total suspended solids, biochemical oxygen demand, and chemical oxygen demand removals in both activated sludge and natural systems were found to be 76.37±18.19% and 61.69±19.0%2, respectively. Also, the two systems were found to be significantly different with respect to their overall efficiency. Moreover, the cost/effectiveness ratios obtained for the two activated sludge and natural systems were 0.23 and 0.58, respectively. Based on the results obtained, it may be claimed that, despite their lower efficiency, natural treatment systems outperform activated sludge ones due to their higher cost/effectiveness ratio, which makes them superior to the activated sludge process. Natural treatment systems owe their superiority to their lower investment, operation, and maintenance costs.