Implementing sustainable sanitation in an integrated model – A straightforward approach for long-term simulation

Abstract

At present, increasing requirements for both the efficiency and environmental sustainability of resources demand more knowledge about the feasibility of the implementation of innovative technologies both in a large-scale as well as in the long run. Even at modified sewage flows and characterizations, water infrastructures must always remain reliable to guarantee sustainable urban water management. Dimensioning methods and assessment variables must be adapted to achieve more flexible systems in the long-term. This paper aims to assess the actual impact of the implementation of New Alternative Sanitation Systems (NASS) as well as stormwater decentralization measures in an existing sewage disposal system with means of a dynamic simulation within a 50-year time interval in 10 years steps. Two scenario simulations showed that the implementation of the module for blackwater and greywater separation with an assumed pollutant fractionation represents the investigated sustainable sanitation measures reliably. Results showed a decrease in the overflow discharge loads and duration of the control stormwater infrastructures. The WWTP showed a successful chemical oxygen demand (COD) and total nitrogen elimination (TN) in all cases. Nonetheless, operational flexibility is fundamental in order to cope with the more unfavorable COD:TN ratios of the WWTP inflow after full implementation of NASS. To sum up, implementing this simplified approach for a stepwise implementation of resource-oriented sanitation technologies allows a dynamic integrated system evaluation not only for dry weather conditions but also for stormwater conditions.