Impact of source-separation of urine on treatment capacity, process design, and capital expenditure of a decentralised wastewater treatment plant

• Published in: Chemosphere (Oxford) 2022-08, Vol.300, p.134489-134489, Article 134489
• Main Authors: Badeti, Umakant, Jiang, Jiaxi, Almuntashiri, Abdulaziz, Pathak, Nirenkumar, Dorji, Ugyen, Volpin, Federico, Freguia, Stefano, Ang, Wei Lun, Chanan, Amit, Kumarasingham, Sanjay, Shon, Ho Kyong, Phuntsho, Sherub
• Format: Article
• Language: English
• Subjects: Capital costs; Decentralised wastewater treatment; Nitrogen removal; Source separation of urine; Wastewater treatment capacity
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.134489

In this study, the impact of urine diversion on the treatment capacity, treatment process, and capital costs of a decentralised wastewater treatment plant (WWTP) was simulated using BioWin. The data for simulation including for economic analysis were obtained from a real decentralised WWTP at Sydney. Simulation was conducted for two alternative process design scenarios of a WWTP: membrane bioreactor (MBR) without denitrification and anaerobic MBR in place of aerobic MBR and compared to existing process design. The simulation shows that with about 75% urine diversion (through source separation), the treatment capacity of the existing WWTP can be doubled although above 40% urine diversion, the impact appears less rapid. When the urine diversion exceeds 75%, it was found that the anoxic tank for biological denitrification becomes redundant and the current wastewater treatment process could be replaced with a simpler and much less aeration intensive membrane bioreactor (MBR) producing similar effluent quality with a 24% reduction in capital expenditure (footprint) cost. Anaerobic MBR can be a potential alternative to aerobic MBR although pre-treatment becomes essential before reverse osmosis treatment for water reuse applications. Sensitivity analysis has revealed that by operating the bioreactor at higher mixed liquor suspended solids concentrations (9 g/L instead of 5 g/L) could help increase the WWTP treatment capacity by about 3.5 times at 75% urine diversion. Hence, urine diversion (until nitrogen-limiting conditions occur above 75% urine diversion) can increase the treatment capacity of an existing WWTP and reduce the capital expenses due to reduced plant footprint. [Display omitted] •Modelled impact of urine diversion (UD) on treatment capacity, process design & CAPEX.•BioWin modelling showed that with 75% UD, treatment capacity can be almost doubled.•Above 75% UD, a simple aerobic MBR is adequate for wastewater treatment.•24% of the current capital costs can be reduced with urine diversion.•At higher MLSS, UD significantly increases treatment capacity of WWTP.