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Multi-pollutant air pollution dramatically occurs in wide range of regions across Tehran. Air quality index (AQI) is applied worldwide to inform the public about levels of air pollution and related to health risks. Assessing air pollution, and transferring information about its possible adverse health effects, may encourage population and policy makers to reduce activities that increase pollution levels. In this study the Air quality index (AQI), Aggregate Air quality index (AAQI), and a relative index of variability (VR) were obtained for the data in order to better investigate air pollution conditions for the whole areas of a city of Tehran, aim at warning the people of short-term health impact. The proposed index of variability does add precious information to the aggregate AQI, as it can demonstrate whether the value assumed by the AQI is influenced by one or more pollutants. The two indices are together used on simulated data and consider different possible scenarios. In addition, Applications to real air pollution data are reported. Before applying the two indices, the effects of different standardizations on data are evaluated from a theoretical point of view.

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Direct application of aerobic biodegradation for leachate treatment is not feasible due to high concentrations of nitrogen and chemical oxygen demand. Several potential leachate treatment schemes incorporating struvite precipitation as pretreatment and two types of activated sludge processes (conventional activated sludge and batch decant reactor (intermittent cycle extended aeration system [ICEAS process]) with and without addition of powdered activated carbon (PAC) were evaluated in this study. The hydraulic retention times (HRT) of 6 h and 12 h were applied in the biological stages of each process. Treatment schemes incorporating PAC addition showed acceptable results. In the conventional activated sludge process, total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), NH(3), and P removal rates were 87, 84, 98.3, and 94%, respectively, with HRT of 6 h and 95.8, 95.1, 99.1, and 98.7% with HRT of 12 h. For the ICEAS process, removal rates were 89.3, 87.9, 98.2, and 94% with HRT of 6 h and 95.8, 95, 99.2, and 98.7% with HRT of 12 h. On the basis of these results, it can be concluded that struvite precipitation, followed by activated sludge process with PAC addition, can be a strong alternative leachate treatment, achieving the standards set for effluent discharges to receiving waters.