Environmental security aspects of the removal of volatile organic compounds

Abstract

With the growing demand for sustainable drinking water supplies and agricultural applications, the practice of wastewater reuse is becoming increasingly important. It contributes to reducing our dependence on limited freshwater sources and mitigating the effects of climate change by conserving water resources. Regarding the recycling of wastewater, however, it must be ensured that hazardous pollutants do not reach consumers. This paper aims to present an application of mathematical modelling to quantify the removal of volatile organic components during treatment and reuse, with regard to operating costs and treated water quality. The study features the model setup of a biological wastewater treatment plant – with post-treatment supplemented by activated carbon filters –, with the goal of quantifying the impact of process parameters on operating and maintenance costs, among effluent water quality. Results of the model simulation demonstrate that increasing the retention time of biomass reduces activated carbon consumption, especially within a range shorter than 6 days; however, from the perspective of environmental security, an operating status below this value should be avoided due to an exponential increase in micropollutant concentrations. Sensitivity analysis has shown that energy demand can be optimised by operating the facility with a sludge residence time in the range of 10-12 days – provided that air supply to biological treatment trains is efficiently regulated. Model runs have shown that, in case of operational emergency scenarios, intensified aeration is a swift and useful operator intervention that provides more efficient stripping[1] of volatile pollutants before loading onto activated carbon columns. The research highlights the potential of dynamic modelling in implementing sustainable operating conditions and emergency planning in wastewater reuse.