Identifying novel wastewater treatment options through optimal technology integration

This paper presents the outcomes of the first of four phases of a research project which aims to investigate the optimal integration of novel, yet largely already demonstrated technologies, in water recycling process train options. The research project has a particular focus on the minimisation of environmental and economic costs in the implementation and operation of the overall recycling process. In the Phase 1 desktop study, novel carbon and nitrogen removal technologies were selected through multi-criteria analysis and incorporated into two concept stage integrated treatment train options. The first treatment train option includes a main-stream anaerobic membrane bioreactor, followed by soluble methane stripping. Nitrogen removal is then achieved with a nitritation/Anammox moving bed biofilm reactor. The second alternative treatment train utilises a high rate/solids contact activated sludge system, with the separated excess biomass treated in a two-stage high-rate anaerobic sludge digester. The digested biosolids stream is treated separately to recover nutrients (as struvite) and to remove nitrogen with a nitritation/Anammox process. Further mainstream nitrogen removal is achieved with a nitrification/denitrification process in a sequencing batch reactor configuration. The two alternative treatment trains were compared to a typical existing treatment train for economics and environmental footprint under Australian conditions at two scales; 10 and 100 ML/d average flow. Engineering analysis included high-level concept design and sizing, estimates of performance, assessment of environmental footprint and whole-of-life cost estimates (including capital and operating expenses). The results of the study indicated that the new treatment trains have the potential to significantly decrease the economic costs of wastewater treatment by between 10 and 46% (based on Net Present Value estimates), and have a lower environmental impact. In Phases 2 and 3, lab-scale and pilot studies are currently underway to further evaluate the performance and confirm the design/operating parameters of the core processes.